Social Capital and how it Influences Migration Essay Example for Free

Social Capital and how it Influences Migration EssaySeveral scholars have given varying definitions of the term hearty bang-up. Social gravid is a term used to refer to features of tender organization such as mesh topologys, norms and cordial trust that facilitate coordination and cooperation for mutual benefit (Putman 67). Fukuyama, an new(prenominal) scholar, refers to it as an instantiated norm that is informal in nature and promotes cooperation among the members (1). Among the various definitions suggested by different scholars, the key notion they all agree to is that societal chapiter can only be present within relationships (Fukuyama 1). In these relationships, co-operation is facilitated by lotd norms and understanding among the individuals touch for mutual benefit. Unlike human capital that is attributed to an individual, the whole concept of genial capital involves accessible connectedness, neighborliness, civic involvement, trust, reciprocity and norms o f co-operation.Researchers have been able to prove individuals with high levels of sociable capital tend to have high educational achievements, better health, better jobs and less criminal activi connections. Social capital is a result of co-operation among individuals who share a similar status within the situation, have common objectives and are guided by event customs. Certain aspects of the social structure facilitate social capital, aspects such as common historical backgrounds and divided up religion. Repeated community interactions lead to the rising of numerous co-operative norms that association the basis for spontaneous generation of social capital. The overlap norms and beliefs that persons ought to or ought not to act in a veritable way determine the boundary to which individuals interacts, for example vacating a seat for an expectant woman on the bus. From time to time, people experience social needs that they have to satisfy. Socially, an individual is patronles s if left all by himself and must interact with other in order to generate social capital to satisfy his needs. Human needs that are non-social in nature and can be satisfied without assistance from other individuals are really few devising the satisfaction of both social and non-social products of a single process.Fukuyama asserts that shared historical experience can grade informal norms and produce social capital (16). Individuals with similar historic backgrounds tend to share a set of norms that in turn lead to co-operation amongst themselves. Religion is a significant contributor to the larger social capital theory by setting some common grounds for co-ordination among its followers. Over the years, religious institutions have been governed by a set of regulations that its members have to adhere to giving rise to certain norms among the community of members. Sometimes social capital is generated for peculiar(prenominal) purposes Individuals may create social networks that will enable him/her achieve a specific objective.Reciprocity norms results in the generation of social capital as it creates in an individual the need and willingness to help others. The desire for better living has also facilitated the generation of social capital where Individuals can acquire and compile other forms of capital through social capital. Both formal and informal networks form the basis of social capital concept. Alberto Douglas confirm that there has been the emergence of social structures based on kinship or friendship. Those associate socially to migrants current migrants or former migrants can access social capital significantly increase their likelihood of migration (Alberto, Douglas, et al1272). The hypothesis has been time and again invoked to give an insight to the concentration of particular types of migrants in certain areas and the magnitude of their migration. Migration is facilitated by Migrant Networks social connections that link migrants, non-migran ts, and former migrants to one another through shared community origin. (Alberto, Douglas, et al., 1262). These set of networks are as a result of the already generated social capital. external migration is advertize fueled by core families already settled in which out-migrants cohere and the established social institutions run in favor of migration. This kind of a connection increase the chances of International migration since the cost and risk involve in the movement is substantially lowered. Chances of out-migration increase each time a relation relocates to a different location. Over time migrant networks become self-sustaining as a result of the social capital that they provide to prospective migrants (Alberto, Douglas, et al., 1286). This fact is commonly observed among siblings where the younger siblings are more apparent to follow suit after the elder ones.The migrant families over time establish themselves first by building social networks among themselves and then wit h the rest of the local population as they accumulate experiences. The migrant grows to the shew where it can sustain itself and continues to admit more migrants into its social relationship. This kind of setup is a social tie the makes it simple for the out-migrants to settle in as it provides a link between sending and receiving communities. Through social network with relatives or friends, the migrants can secure housing, jobs or even financial assistance. Complementary social roles and interpersonal relationships maintained by an informal set of expectations and prescribed behavior keep in bondage both migrants and non-migrants through social capital. This kind of social capital generates over time by virtue of cosmos in a similar region under similar circumstances and not by the migrant process. Through such social ties, those left behind by the migrants can mitigate the loneliness of having a loved one away from them. The migrants also draw upon these ties to share the often , not so favorable conditions of aliveness in exile.The types of social capital people generate while relating to each other are very multidimensional in nature. Different network structures present a different social capital, the goal to be achieved being the determining factor. Social capital can be specific in nature when it is generated specifically to satisfy a given situation, i.e. some kinds of ties are more important for the attainment of particular goals. This network is only instrumental in the achievement of the task. For example, sales managers sitting to strategize on the means to boost the sales of a new product through promotions. Close ties are often than not general social capital and are in most cases informal promoting the well-being of the individual members. Example, offering advice, spiritual condense et. Cetera.ReferencesAlberto Palloni, Douglas S. Massey, Michael Spittel, Kristin Espinosa, Miguel Ceballos and Michael Spittel. Social Capital and Internation al Migration.American Journal of Sociology. 106. 5 (2001) 1262-1298. PrinDouglas Massey, Rafael Alarcon, Jorge Durand, Humberto Gonzales. Return to Aztlan The social Process of International Migration from Western Mexico. Berkeley University of California press, 1987. Print.Francis Fukuyama. Social Capital and CivilSociety.Conference on Second Generation. (1999) web 15 Nov. 2008. www.imf.org/external/pubs/ft/seminar/1999/reforms/fukuyama.htmPettigrew, T. F. Annual Review of Psychology Intergroup contact theory. 49.2 (1998)65-85. Print.Putnam, R. Americas declining social capital Journal of Democracy Bowling Alone.6.1 (1995) 65-78. Print.Source document

Macbeth’s Gender Role Reversal Essay Example for Free

Macbeths Gender Role Reversal EssayWilliam Shakespe ars catastrophe Macbeth completely challenges the idea of traditional sexuality roles and social norms during the renaissance period. The male char actuateers have many fair(prenominal) traits while the female characters have many more masculine and manlier traits. This was going entirely against the stereotypical mindset of the roles youre supposed to shrink from as your gender during that time of history. During the renaissance period women were only pass judgment to clean, cook, and to have babies. Men on the other hand were typically expected to work hard and to turn in for the home. Socially women didnt have power or respect and men were the ones who were supposed to be persist and tough at the best of times and the worst of times. That idea is challenged many times through pop Macbeth as their are several examples where bird Macbeth remains strong while Macbeth crumbles and becomes weak. The play consistently chal lenges the society norms of gender roles.Its obvious the Macbeths dont serve as your stereotypical husband and wife. regenerate away throughout the first couple of acts, Shakespeare introduces doll Macbeths character as an assertive and dominating woman that makes the decisions over her husband Macbeth. noblewoman Macbeth really makes it plain that she wears the pants in there relationship. For example, in scene 1 act 5 when Macbeth tells Lady Macbeth King Duncan is coming and he seems to be actually hesitant on how he will handle the Kings presence. Lady Macbeth takes charge and asserts her authorization by saying, He thats coming/ Must be provided for, and you shall put/ This nights spectacular business into my dispatch (scene 1 act 5 64-66).In traditional society, if the king is coming to your house, it would be in truth unusual for the lady of the house to be in charge of handling the appearance by the king.Lady Macbeth and Macbeth also exchange roles in the way they hand le their emotions and the way they handle the guilt. For instance, when it comes to the thought of murder and death, Lady Macbeth shows no mercy, and when King Duncan was murdered, she remained unphased by the act. This is apparent when she deals with Macbeth leaving the gory daggers at the site of the murder, Give me the daggers. The quiescency and the dead/ Are but as pictures tis the eye of childhood/ That fears a painted devil.(scene 2 act 2 56-58). Macbeth is portrayed as emotionally unstable and soft as he is afraid to sluice go back into the room where the murder took place, Ill go no more/ I am afraid to think what I have done(scene 2 act 2 54-55). This interaction in the midst of Macbeth and Lady Macbeth really shows the unusual roles one another play in their relationship because, in a situation where someone is murdered or there is a serious crime, women arent usually the ones who are brave and strong-minded about it, men are.As the play goes on, Lady Macbeth begins to lose her fierce and frighten persona as Macbeth becomes the more assertive and predominant one. Lady Macbeth starts losing her edge when it becomes less difficult to call for Macbeth to follow through with his murderous acts. Anytime Macbeth thinks youre interfering with his kinship, hell have no problem winning you down and getting you out of his way. Macbeth no longer needs Lady Macbeth to persuade him. This is very apparent when he shows no mercy planning the murder of Banquo, Theres comfort yet, they are assailable/ Then be thou jocund ere the bat hath flown/ His cloistered flight, ere to black Hecates summons/ The shard-borne beetling with his drowsy hums/ Hath rung nights yawning peal, there shall be done/ A achievement of dreadful note (scene 3 act 2 40-44). A completely different Macbeth we see out of this quote, no longer hesitant and no longer appearing to be affected by guilt. at a time that Macbeth is this individual who is ready and eager to kill, Lady Macbeth b egins to show the side of her that wasnt present at the origin of the play, Come on. Gentle my lord/ Sleek oer your rugged looks, be bright and brisk/ Among your guests tonight (act 3 scene 2 26-28). Lady Macbeth expresses emotion and traits of care, unlike any other time.The play Macbeth features many different gender reversals throughout the entire play. Shakespeare really tests the normality of having women be the assertive and dominant one in a marriage while having the man be kind of timid and soft. Lady Macbeth and Macbeths gender reversals distinctively show the extreme traits one another possess and it gives an opposite purview than what we are used to. Whatever goes up always must come down, and when Lady Macbeth and Macbeth begin to corpse into traditional gender roles, that becomes the start of their decline.

Richard vs Richmond Essay Example for Free

Richard vs Richmond Essay1. The source autographment numbers, named Fall In follows the ardour of a simple ABABCDCD pattern, found most commonly in spite of appearance poems. However the second of which is the focus of our analysis, In Flanders Field, is lots different. The first verses pattern is AABBA whereas the second verse is different yet again. Fall In has a style the is a lot more(prenominal) colloquial then Flanders Field relying on using more slang terms to attract the attention of the reader while Flanders Field has a tone that is a lot more easy going and not as in your face. 2. Fall In is much lengthier than Flanders Field its actors line are much more direct and to the point. It contains questions that would make puppyish men designate about how would their families and friends think about them given that they made the choice not to go to war. Flanders field aro social occasions the memories of travel friends and family members within the minds of men thro ughout the land, persuading and coercing them to join the ranks with many another(prenominal)s.3. The first poem Fall In is attempting to recruit young men to the forces by using what could be assumed as a sort of act upon tactic. One can only assume that at the time of its publication the words found within its verses would have struck several chords in the hearts of the audience of young men, no doubt accomplishing its labor movement relying heavily on planting the seed of doubt into the minds of the young men, making them wonder just what thusly their family, friends and potential partners and children would think of their actions and absence from the forces during their countrys time of need.In Flanders Field follows a totally different path. I feel its words are meant to reverberate mostly in the hearts of those who have lost love ones to war before its words encourage those young people to pick up the torch and gazump and carry it anew. I think personalisedly that this p oem would appeal to the more highly educated members of society, its words and underlying message would probably be more attractive to those with a higher education and a deeper understanding for poetry Fall In uses colloquial language, slang and terms used on the bridle-path at the time, it would be much more likely to be understood by the lower tier of educated men.4. Despite my earlier comment that the second of the two poems under analytical scrutinising, I mention the poem Fall In much more affective. It is easy to see how the questions would arose feelings within a young man of the time, not so much forcing but using a clever play on words to make them think that they would be lesser men if they did not do what many other men were doing and signing up for the forces. Being coerced and herded like so many sheep before them.5. The structure of the first poem War Exalts is an unusual one, it is made up of question and answers throughout one question is delightful on the war e ffort and the act of war itself while the reply completely disagrees with it, using phantasmal belief as a main argument in retort. Anthem for Doomed Youth is a praise while the other is not it follows the standard Shakespearean style consisting of 14 lines and five syllables per line. Both poem and sonnet respectively rely on de-idolising war itself trying, one can only assume, to show the deadlier facial expression to it by bringing attention to the point that not every one comes back alive to be praised by their loved ones, many will mourn. Too many.6. I feel on a personal level that the shorter of the two poems is much more affective, this is due mainly to its mention of graven image. Most armies will use God to raise the morale of their troops, or simply to give heartfelt reasoning to their cause with God on their side how could they lose? War Exalts will raise the question within any religious mind what exactly does God think of war itself? To see your creations killing themselves in your name would overrule anyone. Beliefs are harder to change, people fight against them and dont wish to have them altered, is it not better to have a good idea? Truthfully and from the heart this poem touched me, bringing to mind yet again the family members that have, and smooth are, fighting overseas in the name of God and country. Truly an affective poem.

Emotional Bank Accounts Essay Example for Free

Emotional Bank Accounts EssayWe all do things that are counter-productive to our relationships. We all like to stomach people be nice to us. The concept of an mad bank account is powerful, yet non quite as simple as tutelage a ledger of debits and credits. One of the problems is the perception of worth. What is a stay put worth. We may think it is quite valuable. The affected person may consider it so routine it is not even remembered. The trick in making deposits is to know what value the act has for the person holding the account. Herzberg was a psychologist who studied motivational factors in American industry. He came up with the conclusion, since quoted out of context, that money is not a good motivator of people. He called things like money, a safe work place, security and such fundamental principle hygiene factors. That is, the employee needed them to be thither and assumed they would be there. They were not, however, efficient in motivating melodic phrase improvem ent. Herzberg tack together that various methods of showing personal appreciation were far more important. A company play team, a compliment, a letter of commendation, a corner office, painting an employees name painted on a parking place and such activities were more efficient in motivation. Do you agree? some(prenominal) students do not. To many people, money is a prime motivator. How then did Herzberg come up with his findings? Is he maltreat? No, we ingest to understand another theory, Maslows Hierarchy of Needs. Maslow was also a psychologist who studied motivation and found that people had take that varied with their circumstances. If you are living in the weeds, any job that provides 3 hots and a cot is your dream. You think you would never want anything else. But when you get that job, those needs are satisfied and you speedily want more.Maslow said the second stage was to want security. You want those physiological needs to be there in the future, not just today. And, if you get that security, you then go to stage three where you want a feeling of belonging to a group that reflects your value and goals. If you get this feeling of belonging, you then go to a stage where you want to be singled out and honored. The last stage is one where youhave all those needs met, so you want to contribute in some special way to something greater than yourself.Herzberg did his studies in a shop where people had stage one and two pretty much assured. Those physiological elements did not touch off because they were already met. Those people were at the stage where they either wanted to belong to a group or be singled out for honors. The ability to read another person and determine what is important to them is critical. This gets back to our emotional bank account deposit value.Similarly, actions may have different withdrawal value to different people. To mortal who is feeling very insecure because of seeing everyone around them being dismissed in a customary lay off, a curt word may have them dusting off their resume and reacting very defensively. It may not have been intended in that way but its effect is the important thing.Our success in keeping a good emotional bank account with other people then depends upon our sensitivity to the values that other people hold, not our own. This sensitivity is difficult for most of us as we often have tasks to do and keeping track of the effect of our actions and words may not be high on our list of things to do at the moment. Yet, in the long term, nothing is more important. I once comprehend someone say of a particular organization, this place is not about competence, this place is about relationships. I think that is true of just about any organization.

Levers in the Body

prises in the BodyFirst- dissever LeversTypical cases of get-go-class open atomic number 18 the crowbar, seesaw, and jostle extension. An example of this type of jimmy in the ashes is seen with the triceps applying the withalt to the olecranon (F) in extending the nonsupported offshoot (W) at the elbow (A). Other examples of this type of pry whitethorn be seen in the eubstance when the agonist and the antagonist go d hotshot groups on either stance of a conjugation axis argon contr act uponing simultaneously with the agonist producing draw off while the antagonist supplies the protection. A first-class pry is knowing basically to produce balanced trys when the axis is midway among the perpetrate and the subway. When the axis is close to the depict, the jimmy produces fastness and range of app arent relocation (triceps in elbow extension). When the axis is close to the ohmic resistance, the lever produces ferocity question (crowbar).In applying the p rinciple of levers to the corpse it is important to remember that the displume is utilize where the brawn inserts in the jampack and not in the belly of the muscle. For example, in elbow extension with the shoulder fully flexed and the arm beside the ear, the triceps applies the force to the olecranon of the ulna behind the axis of the elbow juncture. As the applied force exceeds the amount of forearm resistance, the elbow extends.This type of lever may be neuterd for a given joint and muscle, depending on whether the ashes segment is in gain with a surface such(prenominal) as a floor or wall. For example, we have demonstrated the triceps in elbow extension world a first-class lever with the deliberate free in space where the arm is pushed upward away from the consistency. By placing the draw in contact with the floor, as in runing a push-up to push the luggage compartment away from the floor, the alike(p) muscle accomplishment at this joint now changes the lever to endorse class because the axis is at the hand and the resistance is the dead frame encumbrance at the elbow joint.In a first class lever, the incubus and force are on opposite word sides of the fulcrumA micro force burn surmount be used to benefit over a heavy weight if a long force armor lever arm mountain be used. Examples of this lever include scissors, crowbars, andteeter-totters.An example of a first-class lever is the joint amid the skull and the atlasvertebrae of the spine the spine is the fulcrum crosswise which muscles lift thehead.Here the fulcrum lies amongst the effort and the cargo. In our bodies, a lever of the first class can be found when the head undergoes nodding actments, i.e. when the occipital condyles articulate with the facets of the atlas. The weight of the face and the head are the resistance. The contraction of the neck muscles is the effort to lift the weight. other example of a lever of the first class is when the bent arm is straightene d . A lever of the first class serves a twofold purpose, i.e. it increases the speed of private road and it exceeds the resistance. In doing so, the resistance (load) is moved in the opposite direction.http//www.botany.uwc.ac.za/Sci_Ed/grade10/ cosmosphys/images/man/1_class.gifLever of the first classSecond Class LeverThis type of lever is designed to produce force meovements, since a lage rsistance can be moved by a relatively small force. An example of a split second-class lever is a wheelbarrow. Besides the example given before of the triceps extending the elbow in a push-up another similar example of a second-class lever in the luggage compartment is plantar flexion of the foot to raise the eubstance up on the toes. The ball of the foot (A) serves as the axis of rotation as the ankle plantar flexors apply force to the calcaneus (F) to lift the resistance of the personify at the tibial articulation (W) with the foot. There are relatively few occurrences of second-class lev ers in the body.In the second class lever, the load is between the fulcrum and the forceA smaller effort can be used to wages over a larger weight. An example ofthis lever is a wheelbarrow.An example in the human body of a second-class lever is the Achillestendon, displace or pulling across the heel of the foot.Here the load lies between the fulcrum and the effort. A lever of the second class run fors on the same principle as a wheelbarrow. A small upward force applied to the handles can get the better of a much larger force (weight) playacting downward in the barrow. Similarly a relatively small muscular effort is required to raise the body weight. In our bodies, a lever of the second class can be found in our feet when we stand on our toes and lift our heels of the ground. The resistance (load) is the weight of our body resting on the arch of the foot. The effort is brought nigh by the contraction of the calf muscle prone to the heel. This leverage allows us to walk. The main purpose of a lever of the second class is to overcome the resistance.http//www.botany.uwc.ac.za/Sci_Ed/grade10/manphys/images/man/2_class.gifLever of the second classThird Class LeverWith this type of lever the force being applied between the axis and the resistance, are designedto produce speed and range of motion movements. nigh of the levers in the hman body are of thistype, which require a great deal of force to move even a small resistance. Examples include ascreen door operated by a short-change jet and application of lifting force to a shovel handle with thelower hand while the upper hand on the shovel handle serves as the axis of rotation. The bicepsbrachii is a typical example in the body. using the elbow joint (A) as the axis, the biceps appliesforce at its insertion on the radial tuberosity (F) to diffuse the forearm up, with its center of dryness(W) serving as the tip of resistance application.The brachialis is an example of true third-class leverage. It pul ls on the ulna just on a lower floor the elbow,and since the ulna cannot rotate, the pull is direct and true. The biceps brachii, on the other hand,supinates the forearm as it flexes, so that the third-class leverage applies to flexion only.Other examples include the hamstrings contracting to flex the leg at the human knee while in a stand upposition and using the iliopsoas to flex the thigh at the hip.In the third class lever, the force is between the fulcrum and the loadIn this case, at that place is no force advantage force is NOT increased. In fact, alarger force is actually needed to move a smaller weight, so there is a forcedisadvantage. The use of this lever is in the gain in speed of movement of theweight.Examples of this lever class include The inside door handle of a car, the gyratespring pulling on a screen door, a pair of finger-nail clippers, and tweezers.An example of a third-class lever in the human body is the elbow joint whenlifting a book, the elbow joint is th e fulcrum across which the biceps muscleperforms the work.Here the effort lies between the fulcrum and the load. In our bodies, an example of a lever of the third class is when the biceps contracts, allowing us to lift more or less(prenominal)thing in our hand. The elbow is the fulcrum, the hand and its contents are the resistance (or load) and the biceps muscles pee-pees the effort. The load can be moved rapidly over a large exceed, while the point of application moves over a relatively short distance. The main purpose of this type of lever is to obtain rapid movement.http//www.botany.uwc.ac.za/Sci_Ed/grade10/manphys/images/man/3_class.gifLever of the third classMore Information About Levers A Brief ReviewF A lever is characterized by a fulcrum, a force arm and a weightarm.F The force arm is the distance from the fulcrum to the point whereforce is applied.F The weight arm is the distance from the fulcrum to the center of gloominess of the weight. First Class Lever The fulcrum i s between the force andthe weight. Second Class Lever The weight is between the fulcrumand the force. Third Class Lever The force is located between thefulcrum and the weight.F Most of the movements of the body are produced by third classlevers.F Third class levers give the advantage of speed of movement ratherthan strength.F Second class levers give the advantage of strength.F First Class levers can give the advantage of strength or speeddepending on where the fulcrum is located.F Since the human body is do up mostly of third-class levers, itsmovements are adapted more to speed than to strength. (Shortforce arm/long weight arm)http//www.botany.uwc.ac.za/Sci_Ed/grade10/manphys/skel_mus.htmRelationship of the length of lever fortifyThe resistance arm is the distance between the axis and the point of resistance application.The distance between the axis and the point of force application is known as the force arm.There is an inverse relationship between force and the force arm just a s there is betweenresistance and the resistance arm. The long-term the force arm, the little force required to move thelever if the resistance and resistance arm remain constant. In addition, if the force and force armremain constant, a greater resistance may be moved by shortening the resistance arm.There is in any case a harmonizeal relationship between the force components and the resistancecomponents. For movement to occur when either of the resistance components increase, theremust be an increase in one or both of the force components. raze slight variations in the locationof the force and resistance are important in determining the efficient force of the muscle.Decreasing the amount of resistance can decrease the amount of force needed to move the lever.The ashes of leverage in the human body is built for speed and range of movement at theexpense of force. Short force arms and long resistance arms require great muscular strength toproduce movement. In the forearm, the a ttachments of the biceps and triceps muscles clearlyillustrate this point, since the force arm of the biceps is 1 to 2 inches and that of the triceps lessthan one inch. Many other similar examples are found all over the body. From a applicative point ofview, this means that the muscular system should be strong to supply the necessary force forbody movements, especially in strenuous activity.Most human activity, and especially strenuous activity, involves several levers working together.As with throwing a ball, levers in the shoulder, elbow, wrist, hand, and lower extremitiescombine to propel the ball. It almost assumes the effect of one long lever from hands to feet. Thelonger the lever, the more effective it is in imparting velocity. root fors in the BodyAthletes display some of the wonderful shows of force that the human body is capcapable of performing.Such force is only attainable with the arrangement of the muscles, bone and joints that make up the bodys lever systems.Bones act as the levers, while joints perform as living fulcrums.Skeletal muscles create motion by pulling on tough cord of connective tissue called tendons. These tendons in turn pull on the bone which creates motion. Muscles move bones with mechanical leverage. As a muscle contracts, it causes the bone to act like a lever with the joint serving as a fulcrum.Muscle exerts force by converting chemical energy (created during respiration) into tension and contraction. When a muscle contracts, it shortens, pulling a bone like a lever across its hinge.Muscles move and this causes us to move. We are capable of performing a wide variety of movements, and, muscle itself moves only by worthy shorter.They shorten and then they rest a muscle can pull plainly it cannot push.There are almost 700 skeletal muscles of the human body, controlled by a few basic principles involving muscle movements or muscular activity.F Skeletal muscles produce movements by pulling on bones or tendons. The tendon gives a very firm anchorage. The point where a muscle is connected to a bone is called the point of insertion.F The bones serve as levers and joints act as fulcrums for the levers. Muscles can only contract a short distance, but since they are attached near a joint, the movement at the opposite end of a limb is greatly increased. The biceps muscle of the arm may contract only 89 to 90 mm, but the hand volition move somewhat 60 cm.F The skeletal or voluntary muscles act in pairs rather than singly. One of the muscles produces contraction while the other allows undoation. Flexion (bending) occurs when contraction causes two bones to bend toward one another, while extension (straightening out) occurs from contraction of muscles, resulting in an increase in angle between two bones. Such pairs of muscles are called out or keeping(p). Often antagonistic muscles are in groups, forexample, both the brachialis and the biceps muscles flex the arm at the elbow and antagonize the triceps, b ut only when the palm is facing upwards. In pairs or groups of antagonistic muscle, one is usually much stronger than the other. The biceps, which flex the arm are larger and more office staffful than the triceps which extends it.F When the body is at rest, the some of the antagonistic skeletal muscles remain in a state of contraction, called muscle tone, which holds the body in rigid position. If the person begins unconscious, or is asleep, muscle tone is lost as the muscles relax completely.Questions1. A first class lever has the ____________ in the middle.2. Give an example of a first class lever ____________________________3. sustain a diagram of a first class lever4. A second class lever has the ______________ in the middle.5. Give an example of a second classlever_________________________________6. Draw a diagram of a second class leverBones as Levers 8M. Poarch 2002http//science-class.net7. A third class lever has the _______________ in the middle.8. Give an example of a third class lever ____________________________9. Draw a diagram of a third class lever10. For EACH of the three classes of levers, develop the advantage gainedby using this type of lever.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________11. What type of lever do we find most oftentimes in the human body?___________________________________________________________12. Explain how a muscle exerts force____________________________________________________________________________________________________________________________________________________________________________________Bones as Levers 9M. Poarch 2002http//science-class.net13. Examine the following diagrams, write down next to apiece meet whichclass of lever the picture represen ts and explain whyLever in thebodyType of lever and whyBones as Levers 10M. Poarch 2002http//science-class.net14. Describe each of the followinga. Advantage (mechanical advantage)b. Antagonisticc. Effortd. Extensione. Flexionf. Forceg. Force armh. Fulcrumi. Insertionj. Jointk. Leversl. Limbsm. Loadn. Muscle toneo. Resistancep. Tendonq. burden arm15.Circle and label eachone example of eachclass of lever on theskeleton.Label the fulcrum,effort and load foreach class of lever.GLOSSARYCENTER OF GRAVITY The point in any solid where a single applied force could support it the point wherethe upsurge of the determination is equally balanced. The center of gravity is also called thecenter of mass. (When a man on a test leans sideways so far that his center ofgravity is no longer over his feet, he begins to fall.) soberness (GRAVITY) The force, first described mathematically by Isaac Newton, whereby any two inclinations in the Universe are attracted toward each other. (Gravitation holds themoon in orbit around the existence, the planets in orbit around the sun, and the sun inthe opaque Way. It also accounts for the fall of objects released near the surface ofthe earth. Objects near the surface of the earth fall at a rate of 32 feet per second.)FREE FALL In physics, the motion of a body being acted on only by gravity.FRICTION The force of one surface sliding, rubbing, or rolling against another. Friction slows down the motionof objects, and can create heat. Friction can also stabilize motion.FULCRUM The improve point about which the lever moves. The point at which energy is transferred.INERTIA The tendency for objects at rest to remain at rest, and objects in uniform motion to continue inmotion in a straight line, unless acted on by an outside force.LEVER A rigid rod or bar to which a force may be applied to overcome a resistance. A lever (or acombination of levers) is a simple machine used to gain force, gain speed, or change directions.LEVERAGE To wield power w ith levers. Under stand up where the fulcrum is located allows us to positionourselves to gain our greatest leverage. mould A device (or system of devices) made of moving parts that transmits, send or changes a force.Machines are often modeled on how the human body works.SCIENCE An organized body of information or HOW THINGS WORKSIMPLE MACHINE Machines powered by human force (as opposed to batteries, electricity or burning fuel)LOADIn bio-mechanics, the body mass is referred to as load.If an object is picked up, the load resultbe that of the body plus the objectbeen picked up. The body weightplace a load on the bone and musclestructures. If no load is applied, thebody pass on stand still (inertia).To move the body load, force needs tobe applied. A lighter body loadrequires less applied force to bemoved and a stronger body leave beable to move the body load hot.The secret of success is for the body to become stronger without the body gaining weight.2.2. FORCE (MOTIVE FORCE)Force = Mass x Acceleration. Force is the strength of the muscle push or pull required to movethe body mass (load). As long as the force applied on the muscle is equal to the load of the body,the body testament not move and will be in equilibrium (state of rest).The force applied by the muscles must be giganticger than the body mass (load) for the body to move.Strengthening the muscles will enable the body to apply a larger force on the bones.The more force muscles apply on the bones, the faster the movement of the limbs will be.The long jump amass clearlydemonstrates how the bodyangle change in accordancewith the force applied. Thebody angle will change toaccommodate the forceapplied.The key operator is how much strength training can be applied on the musclein an attempt to develop force before an injury will occur in the form of a tornmuscle or a broken bone.2.2.1. passive force is a force that does not produce motion (The setposition in the light speedm start).2.2.2. outward-dev eloping force is the force pulling outwards during rotation (Thediscus pulling in the hand during rotation).2.2.3. unifying(a) force is the force pulling inwards during rotation. (Theforce pulling in the shoulder while delivering a discus).2.2.4. Eccentric force is an off-centre force. The centre ofgravity in the human body is more or less situated atthe navel. Delivering a centering needs an eccentric force todeliver the shot, as the shot is held next to the shoulderwhile delivering the shot. Eccentric force requires moremuscle strength than force execute in line with thecentre of gravity. In the sketch it can be seen that theshot is not in line (above) with the centre of gravity. Thekey-factor is to reduce movement away from the centreof gravity by either deliverance the source that requires theapplied force e.g. the shot, closer to the body to avoidmuscle injury.2.2.5. Internal forces will be the force that is applied by the muscles on the bones in the limbs.2.2.6. External fo rces will be the force acting outside the body such as the gravity of the earth andfriction between bodies such as the feet and the ground.2.3. INERTIAInertia is the bodys resistance to change position (Newtons 1st law Law of inertia). If no force isapplied on the body, the body will not move.2.3.1. Moment of inertia = mass x radius squared. Moment of inertia, normally a very shortperiod of time, is the moment the body is standing still or in a state of rest e.g. in pole vault,the trajectory of the body will follow an upwards and downwards motion. At the point whereupwards motion change to downwards motion, a moment of inertia will exist.2.4. WORKWork is force x distance in the direction of force e.g. the amount of time the push or pull of themuscles is required to move the body over a 1500m x the 1500m = work required.The key factor is to develop the capacity of the body to operate at a work rate of e.g. 110% duringtraining. The athletic supporter will then be able to operate at 91% (100% 110%) during competition toachieve success, with less injury risk to the body.If an 800m athlete wants to run 60 seconds per 400m lap in competition, the training repetitionsshould be at 54.6 seconds. Training at oversupply times of 54.6 seconds will enable the athlete run at91% capacity and run a time of 60 seconds in per 400m lap.Mechanical work = product of weight lifted x distance lifted2.5. GRAVITYGravity is a force that is always present. It is the magnetic force of the earth which pulls objectsvertically downwards to the centre of the earth.2.5.1. Centre of gravity is the pointin a body where force acts through with(predicate). A solid body likethe shot or discus will havea fixed centre of gravity butin the human body thecentre of gravity will bedetermined by the positionof the body.2.6. TORQUETorque is the force causing an object to rotate x length of lever arm e.g. a longer arm requires moreforce to deliver a javelin than a shorter arm.Key factor If sufficient force can be exerted on a longer arm, the longer arm is likely to generatemore torque e.g. a longer arm will throw a javelin further than a short arm because more torque canbe applied on the javelin during the process of delivery.2.6.1. External unbalanced torque must be applied to createangular velocity.Newtons 1st law A body will remain at rest, ormotion will be in a uniform straight line, until an foreign force is applied to change its direction isrelevant.To deliver a javelin, an upward and forwardmovement of the arm is required. The arm holding thejavelin will have to exceed the force required to movethe javelin forward as well as to overcome thedownward force of gravity, before a javelin will beable to travel in a temporary upwards trajectory afterdelivery.2.7. AXISAn axis is a straight line about which a body rotates.2.7.1. Vertical axis of the body passes throughbody from top to bottom when standing inthe upright position.2.7.2. Sagittal (also called anteroposterior) axis o fthe body is an axis parallel to the groundwhich passes through the body from bowel movementto back. Key factor The daher will movefrom start to finish as fast as possiblewithout changing the distance of thesagittal axis from the ground (Moving upand down).2.7.3. Frontal axis of the body is the axis parallelto the ground passing through the bodyfrom side to side e.g. the shortest distancebetween 2 points is a straight line. Keyfactor The sprinter will move from start tofinish as fast as possible without changingthe distance of the frontal axis from thesagittal axis (Moving side to side).2.7.4. Horizontal (also called transverse) axis is an axis which is parallel to the ground and can besagittal or frontal.The sketches below show how the 3 axiss is applied in bio-mechanics2.8. ACCELERATIONWhen the body is moving, the speed that it is moving, and the time it labours to move from one point to the next point defines acceleration.Acceleration is the rate of change of velocity.Acceler ation of the body is in proportion with the force applied bythe muscles in the body. More force will ensure greater acceleration.2.8.1. angulate acceleration is the rate of change of angular velocity e.g the angular acceleration ofa high jump shot crossing the cross bar.2.8.2. Positive acceleration means the velocity increases faster and faster e.g. a sprinter outpouringthe 1st 100m of a 400m sprint.2.8.3. Negative acceleration is velocity decelerating (slowing down) e.g. a sprinter discharge the last100m of a 400m sprint and exhaustion is resulting in a reduced muscle force.2.8.4. An object free falling downwards accelerates at 9.8m/sec. e.g. to deliver a javelin, the forceapplied must be more than the body mass, the mass of the javelin and gravity force.After delivery of the javelin in an upwards direction, gravity will continuously pull the javelinback to earth at a rate of 9.8m/sec. The point of return will be when the combined force ofthe body the javelin and gravity are redu ced to a force less than the force of gravity(9.8m/sec).The trajectory of the javelin will consist of positive acceleration (going up), a moment ofinertia (changing direction) and negative acceleration (going down).Key factor The bigger the eccentric force applied during the delivery of the javelin, thelonger negative acceleration will be delayed. (The javelin will travel further before returningto the ground).2.9. SPEEDSpeed is the rate of change of a position. For a sprinter speed will mean the stride length x stridefrequency. For a perspirer speed will mean the speed during take-off. For a thrower the speed willmean the speed during delivery of the implement.2.10. VELOCITYOnce the force applied on the body (muscle contraction), is bigger than the load (body mass), thebody will start moving (positive acceleration). The speed per second that the body change positionin a given direction = velocity. If a sprinter covers 100m in 10 seconds the velocity of the athlete willbe 100 10 = 10m/s.2.10.1. Optimal velocity is sometimes called utmost velocity2.10.2. Angular velocity is the angle through which the body turns per second e.g. during the periodof time that the jumper travels through air after take off.2.11. executionMotion is the continuous change of position. As long as force is applied, motion will take place e.g.as long as the athlete is running motion takes place.2.11.1. Linear motion is movement in a straight line from one point to another e.g. a sprinter fromstart to finish.2.11.2. rotational motion is movement around an axis of rotation e.g. the arms and legs of asprinter is moving in round movements while moving forward.2.11.3. General motion is a combination of linear motion and rotational motion e.g. In the 100m, thebody of the sprinter is moving forward in a straight line but the arms and legs is moving in acircular motion. In discus the thrower moves from the back of the circle to the front of thecircle while the body is turning around in cir cles in an attempt to gain maximum speed of thediscus prior to delivery.2.11.4. Uniform motion is steady, constant motion with unchanged speed e.g a 10000m athlete willtry to run economically in an attempt to maintain the pace of running (uniform motion) aslong as possible.2.12. MOMENTUM whim is the quantity of motion of a moving body. Momentum = mass x velocity2.12.1. Angular momentum is the moment of inertia x angular velocity2.13. FRICTIONThe level of smoothness of two surfaces making contact will determine the level of friction. The even the surfaces, the more likely a gliding (slip) motion will appear when force is applied at anangle.A sprinter has to accelerate as fast as possible. To do this force has to be applied through the feetonto the ground in a running action to ensure forward movement. Fast acceleration may cause thefeet to slip on the ground. To avoid slipping the friction between the feet and ground is increased.This is done by wearing spikes in the running shoes to create as much friction as possible betweenthe surfaces of the track and the running shoes.2.14. EQUILIBRIUMEquilibrium is another word for balance. When the resultant of all forces acting on a body are zero(neutralizing each other), the body is in equilibrium.A body at rest is in equilibrium. The sprinter in the set position is inequilibrium. When you lie still on a bed, the body is in equilibrium. Theforce of the body pressing against the bed and the force of the bedpushing back are equal, resulting in the body lying still. (Newtons 3rdlaw Law of reaction For both action there is an equal and oppositereaction).2.15. ENERGYEnergy is the capacity to do work. There are 2 types of energy2.15.1. Potential energy When the body is standing still (equilibrium) no energy is used, but thepotential for it to move is always there.2.15.2. Kinetic energy is created when the forces applied on the body causes the body to move.The force applied to stop the body will equal the energy used to mo ve. The more force isapplied, the faster the body will move and the more energizing energy the body will have.Injuries occur when kinetic energy is transferred to potential energy to quickly e.g. when the bodycome to a standstill due to external forces such as in a car accident, or the pull on the muscle is tobig for the muscle to handle and the muscle will tear. It is important that once kinetic energy iscreated and the result is a fast moving object, the slowing down process must be within the capacityof the muscles that causes the decelerati

Different Cultures And Clothing Cultural Studies Essay

Different Cultures And Clothing Cultural Studies EssayThe Peranakan retained close to of their ethnic and spiritual origins ( such as ancestor worship), but assimilated the language and culture of the Malayans. The Nyonyas vest handsts, Baju Panjang (Long Dress) was adapted from the native Malays Baju Kurung. It is worn with a hand-dye sarong ( hand-dye wrap- some skirt) and 3 kerosang (brooches). Beaded slippers calledKasot Manekwere a hand-made made with much skill and patience strung, beaded and sewn onto piece of paper with tiny faceted glass beads fromBohemia(present-dayCzech Republic).In modern times, glass beads from lacquer be preferred. traditionalkasot opusekdesign lots have European floral subjects, with colors influenced by Peranakan porcelain and batik sarongs. They were made onto flats or bedroom slippers. But from the 1930s, modern shapes became popular and heels were added.In Indonesia, the Peranakans develop their own Kebaya, close to nonably kebaya encim, and developed their own batik patterns, which incorporate symbols from China.for the Baba they will live baju lokchuan(which is the Chinese workforce total costume)but the younger generation they will live on just the top of it which is the broad sleeved silk jacket with Chinese collar or the batik shirt.Malay hang alsoMalaysian MalayTraditional Malay attire is the baju melayu, a loose tunic which is worn over trousers and usually accompanied with a sampin, which is a sarong which is wrapped approximately a mans hips.1It is also often accompanied with asongkokor cap, on their head. Traditional attire for men in Malaysia consists of a silk or cotton skirt and shirt with a jerk off like piece of cloth fastened around his waist. This scarf is sewn together at the ends and is traditionally called a sarong or akain. Most of the clothing is made up of bright and bold colors. The man also fag outs a religious hat.Malay women wear thebaju kurung, a knee joint-length blouse worn over a extensive skirt. Usually a scarf of shawl is worn with this. Prior to the wide embrace of Islam, Malay women wore kemban, which were sarongs which were tied just above the chest.1ChineseSee alsoMalaysian ChineseThe classical everyday clothing for men in Malaysia is a short sleeved shirt worn outside the trousers, light-weight trousers and informally, sandals for comfort.The Chinese women wear thecheongsam, a one-piece dress with a high collar, diagonally closed with small clips or toggles ( stuff clasps). It sometimes notify have slits at the side, as is made with a soft fabric such assilk.1The cheongsam is especially popular around the time of the Chinese New Year and other formal gatherings (the one-quarter and fifth women from the right in the picture above). Older well-respected women wear asamfoo, which tonuss like pajamas with a enjoin loose fitting top fastened by toggles and ankle length, or above the ankle, pants.IndianSee alsoMalaysian IndianIndians in Malaysia as with elsewhere in the world wears bees, a cloth of 5-6 yards which is usually worn with apetticoatof a similar shade. It is wrapped around the dead body so that the embroidered end hangs over the raise, while the petticoat is worn above the bellybutton to support the saree, which can be made from a wide variety of materials. The PunjabiSalwar kameezis popular with women from northern India, and is a long tunic worn over trousers with a matching shawl.1The fabric imported from India, made of the best type silk is used in making saris. There are two layers to a sari a long bright colored dress decorated with psychedelic beads sewn on it to make it look more attractive, and a wrap, a piece of straight fabric draped around one shoulder which ties across the body around the waist area. Women with a high standing will have their clothing made from gold and silver thread with elaborate beading.In formal occasions indian men wear the kurta, a knee-length shirt usually made from cotto n or linen.1The Indian men wear Sherwani, Lungi, Dhoti and Kurta-Pajama.The Sherwani a coat like garment fitted close to the body, of knee-length or daylong and hatchway in front with button-fastenings. Below the men wear a garment for the lower part of the body, quaggy and wide at the top tied with a string at the waist , and tight around the legs and ankles. elhi.The Lungi The traditional lungi originated in the south and today it is worn by men and women alike. It is simply a short length of material worn around the thighs rather like a sarong.The Dhoti The most ancient recorded Indian drape is a dhoti. They require a piece of cloth which seems longer and larger than what was worn in the past, but their pleating is often simpler, and they are not adorned with belts anymore. every dhotis begin with the same basic closing. It is the only drape that doesnt start from one pallav but from the centre of the fastness border. The middle of the cloth is tied around the hips. Each en d of the cloth is then draped around the leg on its side.The Kurta-Pyjama The Kurta or the top is a knee length colarless shirt which is adorned inmostly ashen or pastel colors. But today you will find Kurtas made out of the most fantastic and colorful of fabrics. Pyjama-are like loose trousers with a string tie at the waist. Traditionally white in color.Orang AsalSee alsoOrang AsalBefore the creation of ancient kingdoms, most aboriginal people wore bark costumes decorated with beads. In the times of early kingdoms hand-crafted textiles were used, and trade from other areas brought other outfits such assilkcostumes,pulicatsandsarongs, andjubbahs. TheOrang Aslistill wear clothing of natural materials, often out of treebark and skirt. Leaf fronds are sometimes crafted into headbands or other ornaments.1InEast Malaysiasimilar clothes are worn. TheOrang Uluwear hand-loomed cloths as well as tree bark fabrics. Beads and feathers are used for decoration. TheIbanare known for their woven pua kumbu. Another well known clothing item is the songket of the Sarawak Malay. In Sabah the clothing of unalike nations differs with different amounts, with tribes in close proximity having similar clothing. Notable ones are theKadazan-Dusunstraw hats for ladies, the dastar of theBajau. Men from the Lotud tribe wear a headdress which has a number of fold points equal to the number of his wives.1OthersOld Chinese immigrants who married Malays and adopted some of their culture are known as theBaba Nyonya. They wear kebaya, which are hard-made lace-word clothing, often with intricate embroidery.1Those descended from the Portuguese often wear Portuguese-style outfits. Men often wear jackets and trousers with waist sashes, while women wear broad front-layered skirts. The dominant colours are black and red.1GlossaryBaju Kurung Kedah worn only by Malay women as a daily dress for married women. it is a shorter dress with three-quarter sleeves, so the wearer can perish around easily.Ba ju Batik worn by men and women on a formal occasion. Usually colorful cotton printed in thebatikor wax resist method of dyeing.Baju Melayu worn by Malay men, it does not have any buttons but has a special kind of button called a butang. The fabric used to make a baju melayu is made from either nylon, satin, or silk. Along with this is asongkokorkopiah, worn on the head. Songkok are generally a dark natural color, and the kopiah is a white color and represents purity.Baju Kurung a baju kurung is worn by women for occasions such as school (as a uniform) or to a wedding. It excessively is brightly colored and can come in a variety of different printed designs. It is a knee length dress with a full length sleeves.Baju Kebarung is a combination of the baju kebaya and the baju kurung. It is loose and almost reaches the ankles it is not one of the traditional clothes of the Malay, but an adaptation.

The Evidence For The Endosymbiotic Theory

The Evidence For The Endo dependent Theory synopsisModern eucaryotic cubicles were to begin with believed to have arisen directly from a single prokaryotic ancestor through serial mutation and the process of genetic drift. However, much evidence has lead scientists to believe that eukaryotes be the termination of a merger surrounded by a prokaryotic cellular phone, a relative of modern -prote bacterium, that became incorporated by a army archaeon. This is referred to as the endosymbiotic guess. Over the span of millions of days, symbiont deoxyribonucleic acid was transferred to the effect to give rise to the eucaryotic genome and the prokaryote gave rise to mitochondria. As such the two organisms effectively become a single organism, each(prenominal) uneffective to survive in the others absence. The endosymbiotic theory is widely regarded referable to the many shared biochemical and geomorphological characteristics of mitochondria with bacterium, including DNA or ganization and connaturalities protein synthesising machinery and membrane composition. In reviewing these characteristics I have come to conclude that an endosymbiotic event is the close to plausible explanation for the development of mitochondria indoors the eucaryotic cell, despite the un certain(prenominal)ties regarding the nature of the prokaryotes inclusion in the legions cell.IntroductionThe term endosymbiosis refers to the event in which one organism takes up permanent residence within some other, such that the two develop a mutually beneficial relationship1.The endosymbiotic theory was real to explain the phylogenesisary discontinuity between the appearance of prokaryotes and eukaryotes, and the great many differences exhibited by the two taxa, described in Table.1. Since mitochondria share so many biochemical and structural characteristics with Bacteria, an evolutionary relationship was proposed, in order to explain the transition from prokaryote to eukaryote2. C ontrary to the traditional view that a series of chance mutations were responsible for the evolution of eukaryotic cells, the endosymbiotic theory states that mitochondria arose by the incorporation of a promiscuous living aerobic prokaryote, relating to an -proteobacterium, into an anaerobic proto-eukaryote3. This is proposed to have occurred approximately 1.5 one million million million age agone, between the kickoff fossil record of aerobic prokaryotes and eukaryotes (Table 1), after oxygen had begun to accumulate in Earths atmosphere as a will of the emergence of photo celluloid organisms4 5. Rather than being digested, the prokaryote remained as a symbiont, helping in the production of ATP within the host by the process of aerophilic phosphorylation, enabling it to survive the increasing oxygen c configurationerlyntrations, thereby giving it a selective advantage all over anaerobic cells. Inter dependency between the aerobic bacterium and the host cell developed and, t he bacterium evolved into the mitochondrion. photosynthetic eukaryotes originated in a similar manner by a turnary symbiosis between these organisms and photoautotrophic bacteria related to to cyanobacteria.Wallin proposed in 1923 that mitochondria originated from an endosymbiotic event when he find that they closely resembled bacteria in size and complexity7. These and related observations led Lynn Margulis to publish Symbiosis in stall Evolution in 1981, in which she argued that modern eukaryotes were originally trunked from a fusion of separate species. Margulis also proposed, to a greater extent controversially, that motile prokaryotic species such as Spirochaeta were incorporated and issueed in the evolution of the organises that provide cellular motion. Since this hypothesis is generally not accepted, it is not discussed in further detail here.1. Over the next thirty years, further similarities between mitochondria and bacteria were engraft that supported Margulis work . Table 1 described some of the similarities observed between prokaryotic cells and mitochondria when compared to eukaryotic cells. include are the overall physiological similarities of mitochondria and prokaryotes, such as the similarity in size compared to eukaryotes, similarities between the protein-synthesising machinery such as the mitochondrial ribosomes and tRNA molecules, and the presence of a separate mitochondrial genome.3 8Table.1 Summary of the similarities between prokaryotes and eukaryotes, and eukaryotic organelles. fit from Indiana University-Purdue University Department of biota (2004) Class Notes The Endosymbiotic Theory Available http//www.biology.iupui.edu/biocourses/n100/2k4endosymb.html Accessed 16/04/10ProkaryotesEukaryotesMitochondria of Eukaryotic cellsDNA1 single, circular chromosomeMultiple linear chromosomescompartmentalized in a nucleus1 single, circular chromosome sound reflectionBinary Fission involving Fts proteinsMitosisProcess akin to binary Fission involving dynamin proteinsRibosomes30S and 50S Subunits40S and 60S Subunits30S and 50S SubunitsElectron Transport Chain be in the plasma membrane around cellFound only in the cells mitochondriaFound in the plasma membrane around mitochondrionSize (approximate)1-10 m50 500 m1-10 mFirst appearance in fossil recordAnaerobic bacteria3.8 Billion years agoAerobic bacteria 2.5 Billion years ago1.5 billion years ago1.5 billion years agoWhat the endosymbiotic hypothesis does not make clear is the order of events regarding the formation of the nucleus and the acquisition of the prokaryotic cell containing the precursor mitochondrial genome. Two hypotheses have been put forward for the formation of the eukaryotic cell, illustrated in Fig.2. nucleus formation preceded symbiosis of mitochondrion and chloroplastNucleus formed after symbiosis of mitochondrion and before chloroplast taken from Michael Madigan et al. Brock Biology of Microorganisms(2008) 12th edition, Pearson Education IncThe most widely regarded, summarised in Fig.3, proposes that an ancestral prokaryote first developed a membrane around its DNA from infolding of the plasma, similar to the way in which the endomembranous system of the endoplasmic rectilium and Golgi apparatus is thought to have arisen3. This organism, dubbed the protoeukaryote engulfed a small heterotrophic prokaryote, shown on Fig.2 as the ancestor of mitochondrion9.Pearson Education Inc.http//topicstock.pantip.com/wahkor/topicstock/2009/09/X8338687/X8338687-8.jpgThe second hypothesis, in contrast, considers that there could have been a nucleus was formed after the acquisition of the protomitochondrion, when a extremity of the Archaea acquired the bacterial ancestor of the mitochondrion through endocytosis11. This is known as the hydrogen hypothesis, proposed by Martin and Muller (1998), who claimed that the symbiotic relationship between the two cells was initially based on the hosts dependence on the hydrogen, evolved by the symbiont a s a by-product of anaerobic respiration, as a antecedent of energy. The nucleus was formed from the mitochondrial DNA from the symbiont and the free DNA residing in the nucleus12. Both models thus involve the transfer of a large portion of mitochondrial DNA to the host nucleus, resulting in the dependence of the symbiont upon the host.An alternative hypothesis has recently been forwarded by Davidov and Jurkevitch, who propose that the ancestors of mitochondria were not endocytosed by Archaea but were predators that penetrated the host and devoured the host. The prey managed to survive and established a mutualistic relationship as in the antecedent hypotheses. (Davidov, Jurkevitch cited by Zimmer, 2009) This appears to be supported by the finding that certain species Rickettsia, obligate intracellular para grades, have more similar genomes to the than mitochondrion13 14.However the eukaryotic cell arose, abundant evidence has accumulated that supports the endosymbiotic theory, and the evidence of similarities relating to different functions of bacteria and mitochondria are reviewed in this audition. There is also an increasing body of experimental evidence that suggests that endosymbiotic events occur in modern cells, and two such experiments and their implications on the endosymbiotic theory are reviewed here. Aside from these experiments, the evidence kick ined in this essay relates entirely to the emergence of mitochondria.The Mitochondrial GenomeMitochondria possess their own genomes that replicate that replicate independently from the nucleus, using DNA polymerases circumstantial to the mitochondria. These processes, as well as the subsequent DNA transcription and protein synthesis take place in the matrix of mitochondria and occur throughout the cell cycle, which parallels the situation in bacteria but is not real of thermo thermonuclear DNA2. The DNA of mitochondria is a single circular molecule of roughly the same size as the bacterial genome, an d has a mean GC content ranging from 20-50%. This is close to the variation comprise in bacterial species and greater than observed for eukaryotes, reflecting phylogenetic relationships of mitochondria and bacteria2. Furthermore, like bacterial DNA, the DNA of mitochondria lacks both intervening sequences and the organisation into histones present in bacteria3. Comparative molecular sequencing of mitochondrial genes and the RNA they encode has revealed that the mitochondrial genome is more closely related to that of organisms such as the -proteobacterium Rickettsia prowazekii than to the rest of the eukaryotic cell, indicating an extracellular origin10 15. Similar sequencing by Ito and Braithewaite has revealed that yeast mitochondrial DNA polymerase I is homologous in amino acid sequence the DNA polymerases, of E. coli and Streptococcus pneumoniae in both the 3-5 exonuclease and DNA polymerase domains. The similarity of the deoxyribonucleic acid replication machinery further impl ies that mitochondria evolved from prokaryotes.While nuclear DNA is contributed by both parents in sexual organisms, mtDNA is contributed virtually entirely by the oocyte16. The symbiotic concept accounts for this non-mendelian mode of inheritance and indicates the evolutionary importance of maintaining uniparental heredity of nonchromosomal genes, due to the inherent redundancy that results from the fusion of gametes, This ensure that at least one copy of the organellar genome is maintained at each stage in the eukaryotic cells life cycle3.DNA sequence analysis has also exhibit the presence of mitochondrial DNA in the nucleus17. Biologists originally believed that the nuclear DNA of the eukaryote coded for mitochondria. However, Margulis reasoned that, if the endosymbiotic hypothesis represents the veritable course of events in the evolution of mitochondria, then upon entering a symbiotic partnership, the symbionts would lose all synthetic capabilities except the ability to repl icate their own DNA. It has been shown that that the proteins that mediate function of the mitochondrion are encoded both in the mitochondrial and the nuclear genome and must be imported to the mitochondrion, shown in Fig.3 which supports Margulis hypothesis. Margulis Although many mitochondrial genes have been found in the nucleus, nuclear genes direct the synthesis of only some of the proteins from which they are made, thus cells which lack mitochondria cannot generate them1. This appears to be the result of extensive gene transfer that took place after the endosymbiotic event which brought the two cells together. The transfer of essential genes to the host nucleus resulted in the progressive loss of independence after the host acquired the symbiont, resulting in an organelle unable to survive in oxic conditions outside the host3. O Daley proposes that the large transfer of mitochondrial DNA whitethorn have been the result of evolutionary pressure to accumulate DNA inside the nucl eus, due to increased genetic variation 17 18.The High rate transfer of DNA between the nucleus and mitochondria demonstrates that the incorporation of the mitochondrial genome into the eukaryotic cell was vital in defining the eukaryotic genome18.An external file that holds a picture, illustration, etc., usually as some form of binary object. The name of referred object is ch14f62.jpg.Fig 3 Transfer of nuclear precursor proteins from the nucleus to the mitochondrion and subsequent production of mitochondrial protein. Red arrows indicate the situate of action of a item inhibitor of either nuclear or mitochondrial protein synthesis, discussed in more detail later in of this essay.From Bruce Alberts, Dennis Bray, Julian Lewis, Martin Raff, Keith Roberts, and James D. Watson (1994) Molecular Biology of the Cell. 3rd edition, Garland Publishing Inc., New York.Lipid membranesPossibly the most convincing evidence of the extracellular origin of mitochondria is the similarity between the interior mitochondrial membrane and the membrane possessed by bacteria. Mitochondria are meet by two phospolipid membranes, and while the outer(a) membrane resembles the eukaryotic membranes, including the membranes of other cellular organelles such as that of the nucleus and endoplasmic rectilium, the privilegedmost membrane is chemically distinct to those found elsewhere in the eukaryotic cell6. Furthermore, microscopic observation has enabled the comparison of cristae, invaginations of the interior mitochondrial membrane, shown in Fig.4, to bacterial mesosomes, shown in Fig.5. Both structures increase the surface playing area of their respective membranes and provide a site for the process of oxidative phosphorylation. Margulis has suggested that the similarity between mitochondrial cristae and the mesosomes possessed by many species of Bacteria (Fig. 5) also alludes to the extracellular origin of mitochondria3. Consistent with the endosymbiotic theory, it has been reasone d that the inner membrane once belonged to the bacterial symbiont, and that the outer membrane was a remnant of the phagocytic vacuole in which the symbiont was engulfed by the host cell, resulting in the development of cristae from mesosomes9.LeftFig.1 Structure of an idealised mitochondrion as compared to an electron micrograph. Illustrates the double membrane structure and the infoldings of the inner membrane known as cristae on which oxidative phosphorylation occurs.Adapted from Dr Jay Pitocchelli, Saint Anslem College (2001) Lecture Notes for Cell Biology. Available http//www.anselm.edu/homepage/ jpitocch/genbio/mitochondrion.JPG accessed 27/04/10RightFig. 5 Electron micrograph of thin section of T.dentrificans showing inverted Y form of simple mesosome-like body.From J W Greenawalt and T L Whiteside (Dec 1975). Mesosomes membranous bacterial organelles. Bacteriological Review. 39(4) 405-463.The inner mitochondria and bacterial membranes also share many biochemical features. T able 2 illustrates the observations made by Parsons, that the outer mitochondrial membrane is more similar in density and lipid composition to that of the endoplasmic reticulum of Serratia than of the inner mitochondrial membrane3 19. It has also been noted that -barrel transmembrane proteins are exclusively found in the bacterial membranes and in the outer membrane of mitochondria, and that the amino acid sequences of these proteins show high similarity6. Additionally, LACTB, a protein that derives from bacterial penicillin-binding protein of peptidoglycan, has been found in the intermembrane space of eukaryotic mitochondria20. While mitochondria lack peptidoglycan, the presence of a vestigial peptidoglycan-forming protein provided further evidence that mitochondria are descended from bacteria.Table 2 Comparison of structural features and lipid composition of inner and outer Mitochondrial membranes and ER of Serratia.Adapted from D.F. Parsons (1867) Ultrastructural and molecular as pects of cell membranes. Proceeings of the Seventh Canadian Cancer Research Conference 7193-246.The nature of the mitochondrial respiratory system raises another significant line of evidence supporting the endosymbiotic theory. The production of energy via the electron transport drawstring by mitochondria is associated only with the inner membrane, as in prokaryotes, and does not occur in the outer membrane, as show by the difference in electron transport protein content in the mitochondrial membranes, shown in Table 29. Additionally, the membrane potential across the inner membrane that is necessary for the production of ATP is not found in the outer membrane of the mitochondrion or in eukaryotic membranes. Table 3 also demonstrates that that bacteria such as P. denitrificans and mitochondria share many respiratory features, such as the sensitivity of the oxidative chain to antimycin, which disrupts proton gradient formation across the membrane. Furthermore, the electron-transpor t chains of bacteria and mitochondria both contain a membrane-bound enzyme complex that accepts electrons only if from ubiquinone-10 quinine carrier3. Taken together, this evidence supports the theory that the outer membrane of mitochondria was formed from the vesicular membrane during an endosymbiotic event and the inner membrane formed from the prokaryote engulfed2.Table 3 Mitochondrial features of Paracoccus denitrificansIllustrates the similarities of the respiratory system of mitochondria to the systems of Paracoccus , that are also found in many other bacteria. These strikingly similar respiratory features indicate that microbes such as P. denitrificans may be the ancestors of mitochondria. Many of these features are found in other bacteria. After Whateley (1977) Adapted from Lynn Margulis. Symbiosis in Cell Evolution (1981) W.H.Freeman Co Ltd.Respiratory ChainSuccinate and NADH dehydrogenasesUbiquinone-10 is the sole quinineCytochromes a and a3 act as oxidase light-sensitiv e to low concentrations of antimycinOxidative PhosphorylationRespiratory control is released by ADP or by uncouplers of oxidative phosphorylationATPase has tightly bound nucleotise exchangeable on energizationMembrane PhospholipidsPhosphotidylcholine is the main constituentAll fatty acids are straight-chain and monounsaturatedMitochondrial varianceThe way in which mitochondria divide also provides evidence for their extracellular origin. It has been shown that these organelles multiply semi-autonomously, not through mitosis as eukaryotic cells are, but rather through a process similar to binary fission of preexistent organelles21. Mitochondria been found to possess dynamin proteins, mechanochemical GTPases, that are related to the FtsZ, filamentous temperature sensitive, proteins found in bacteria. Bacterial FtsZ2 proteins interact to form a divisome ring complex that from a division furrow from outside, a similar mechanism has been observed by the Dnm1 protein of mitochondria, wh ere the proteins constrict the membrane from the outside, illustrated in Fig. 6. Furthermore, evidence of FtsZ proteins have been found in the mitochondria of the alga Mallomonas splendens that are proteins closely related to those of -proteobacteria. The FtsZ protein is located in patches on the mitochondrial membrane, near the centre or at the ends of mitochondria, similar to the location of Dnm1. The similarities in the molecules involved in initiating bacterial and organelle division further emphasise the evolutionary ties that these organelles have to bacteria.9 22 23Fig. 6 A model of the mechanism of mitochondrial division Dynamins are targeted to their site of action by other proteins. After modification by GTP, Dynamins from rings that tighten around the site of division and constrict to cut the mitochondrion into two. This mecahism parrales that of FtsZ, the tubulin protein of bacteria.Adapted from Suzanne Hoppins, Laura Lackner, and Jodi Nunnari (2007) The Machines that Di vide and Fuse Mitochondria. Annual Review of Biochemistry Vol. 76 751-780Ribosomal SimilaritiesThe protein-synthesising machinery of mitochondria shares more similarities with bacteria than that of the eukaryote cytoplasm. For example, the initiating amino acid in the transcripts of bacteria and mitochondria is N-formylmethionine, whereas protein synthesis in the cytosol of eukaryotic cells begins with methionine. The structure of the mitochondrial ribosomes also differs from those found in the eukaryotic cytoplasm, in that they are more similar in size and share the same subunit structure, described in Table.1 3 9. The sequences of 16S ribosomal RNAs are closer to certain aerobic eubacteria than many other bacteria are, for example, Wolters and Erdmann have confirmed, by phylogenetic analyses, that the primary and auxiliary structure of 5S and 16S rRNA of angiosperm mitochondria share specific signatures with a particular type of purple bacteria, the rhodobacteria25. Conversely, m itochondria show no homologies in these traits with the eukaryotic cell cytoplasm3. These similarities appear to confirm the phylogenetic relationship of these organisms and the organelles.Similarities between the ribosomes of bacteria and mitochondria are further evidenced by the action of a shape of antibiotics that affect only bacterial, mitochondrion ribosomes protein-synthesising machinery. Fig. 3, above, demonstrates specific inhibitors of protein synthesis. These similarities the action of antibiotics between three types of ribosomes are illustrated in Table 4 3. For example, neomycin and streptomycin act by binding the 30S subunit of mitochondria and bacteria and inhibiting protein chain initiation, while chloramphenicol blocks the attachment of amino acid to tRNA9. none of these chemicals interfere with protein synthesis in the cytoplasm of the eukaryotes. Conversely, cyclohexamide and anisomycin affect only the protein synthetic machinery of eukaryotic cells, and have no inhibitory effects on mitochondria or on bacteria. Another example, rifampicin, inhibits the RNA polymerase of bacteria and mitochondria, but has no such effect on eukaryotic nuclear RNA polymerase. It is notable that each antibiotic, except for Puromycin, affects both mitochondrial and bacterial or cytoplasmic ribosomes, and this would appear to suggest a relationship between the protein synthesising machinery of mitochondria and that of prokaryotic bacteria from which they were thought to have originated3.Experimental EvidenceLaboratory experiments have been conducted to confirm the establishment of endosymbioses in some(prenominal) organisms. Kwang Jeon of the University of Tennessee has demonstrated that, under laboratory conditions, it is possible to observe the establishment of a stable amoeba-bacteria symbiosis. After over 20 years of culture, a strain of Amoeba proteus became infected with a large number of bacteria. These became integrated as necessary cell components afte r initially being pathogenic to the host cells26. The amoebas dependence on the endosymbiotic bacteria was also demonstrated by removing the nucleus of an infected cell and placing it into another cell that had previously had its nucleus removed. Treatment with chloramphenicol also killed the majority of the endosymbiotic bacteria, which rendered the amoebae unable to survive. Thus, Jeon had proven that the host nucleus had become dependent on the symbionts 3, 27.Finally, Okamoto and Inouye have shown that some organisms can take opportunistic advantage of a similar process to endosymbiosis, by observation of a heterotrophic protist that engulfed a unicellular greens alga and used the products of its photosynthesis. Inside the host cell, the alga underwent morphological changes, including the loss of flagella and cytoskeleton. The heterotrophic host switched its source of nutrition and became an autotroph, and became capable of phototaxis, the ability to move towards light. (Kimbal l, 2007) The acquisition of the alga by the protist and subsequent changes in both cells are believed to represent the early stages of a secondary endosymbiosis in process, and the conclusions of both experiments illustrate the mishap of secondary endosymbiosis occurring in modern cells in a similar way in which the symbionts from which mitochondria are descended were acquired28. proofBased upon the large body of available evidence contributed by scientists in the years since the endosymbiotic hypothesis was first proposed, including the conclusions of various experiments and the sequence data of nucleic acids and proteins, I have concluded that modern eukaryotic cells arose by a stable incorporation of prokaryotic endosymbionts. This dramatic change was then the driving force behind the evolution of new species and eventually more complex organisms4. However, the question of which order eukaryotes came to possess nuclei and respiratory organelles is still the dependent of much de bate, and the fact that some genes remain encoded in the mitochondria rather than being completely transferred to the nucleus has not been accounted for16. Despite these uncertainties, the endosymbiotic theory remains the most probable explanation for the similarities between mitochondria and Bacteria, and the large disparity between Bacteria and eukaryotes. The next steps in the development of this theory may require new methods of reconstructing events that occurred billions of years ago, in order to answer one of the greatest uncertainties in evolutionary biology, regarding the origin of the eukaryotes.