Meiosis celular y su relación con las alteraciones cromosómicas sexuales

LA MEIOSIS  es el proceso de division celular que atraviesan glandulas sexuales para producir los gametos, el óvulo y el espermatozoide. Durante este proceso, una célula dipolide realiza dos divisiones sucesivas con la capacidad de generar cuatro células hijas haploides los cuales poseen la mitad de cromosomas, es decir 23.  El proceso ocurre en dos etapas fundamentales MEIOSIS I y MEIOSIS II.

Este proceso tiene una importancia fundamental ya que mediante este se produce la recombinación genética, responsable de la variabilidad genética.

Sin embargo, hay veces en que producto de un error de la division celular de las gametas se producen ANOMALÍAS CROMOSÓMICAS correspondiente a un número anormal de cromosomas sexuales. En el momento de la fertilización, cuando se juntan un óvulo con un espermatozoide, se origina el número normal de cromosomas del feto, en humanos 46. Si durante la meiosis, un óvulo o espermatozoide tiene una anomalía cromosómica, el feto podrá recibir un cromosoma adicional "trisomía" o uno en falta "monosomía". 

Esta anomalía se debe a la no disnyuncion de los cromosomas sexuales. En los varones se podría producir espermatozoides ya sea con 22 autosomas y ningún  cromosoma sexual (espermatozoide "O")  o bien con dos cromosomas sexuales "XX", "YY" o "XY". Sin embargo en las mujeres, la no disnyunnsion produce óvulos "O" o "XX" en vez de un cromosoma X. 

El problema surge cuando los gametos normales se combinan con aquellos defectuosos, el número de autosomas es normal, pero el de los cromosomas sexuales es anormal, las mas comunes son:

•  XO --] Mujer: Síndrome de Turner
• XXX --] Mujer: Trisomía X
• XXY --] Varón: Síndrome de Klinefelter
• XYY --] Varón: Síndrome de Jacob
• YO--] Muere en estado embrionario, esto se debe a que los genes del cromosoma X son indispensable para la supervivencia, de manera que al no tenerlo el embarazo termina en aborto en una etapa temprana de su desarrollo.

Pink Floyd - The Wall

After watching in class the movie "Pink Floyd - The Wall", the teacher gave us a set of questions I will be answering below:

1. This portrays how society was educated based on equality as what is socially accepted regardless of their identity, where everyone is enclosed to follow a standard stereotype. Masks in both situations represent people as faceless individuals which are part of a machine and are all somehow the same. They were shaped under certain ideals and cannot be set free so as to think by themselves
   
2. The riot scene was all in the boy's mind; he was imagining what it would be like to step aside from that stereotype that everyone was pressured to form part of. The scene begins with the teacher mocking the kid's imagination and creativity, in other words we can say that being different was not accepted. Therefore the kid afterwards begins to imagine what would it be like to break the order and stand out of the stereotype. However, the scene comes back to the class at the end, to show that they are still being under a strict control, and expressing their feeling is not acceptable. 
3. The movie portrays a tough and strict kind of education. We can see how the teacher follow a certain educational structure which should be respected by the children and if they didn't they were punished. Moreover every actitude a student had that showed him different to the rest was considered as a weakness and used to embarrass him.
4. The movie deals with various social institutions which are the government, education and the family. As regards the government we can mention it to be what controls everything by the education. They are who decide what what we should learn in order to grew up following their beliefs. The government’s purpose is to making us follow a same stereotype for they to keep the control of everything, and control means power. Therefore we can say that what the government looks after is power, which is just accessible if they force us to think like them. On the other hand, the family is the other institution portrayed in the movie, we can see how Pink losses his father after the wall and all he has left was his mother, yet she seems not to be present in his life. We can say that family is important for us, it represents who we will become, since parents are who we looked after when we are kids. This can be shown in the scene were he wears with his father uniform imitating him. This is why we can say that the movie presents to us different social institutions which have the same purpose, since these are what will guide us during our childhood to grow up and will determine our future.
   
5. The phrase “We, in Argentina, often rely on education to solve most of our social problems. We blame education, or the lack of it, for many of them” is something that you always listen here, and we constantly repeat too. However, we think that what the film what is trying show us, is that aggressive and repressive style of teaching children, where students are blame of thinking different. 
6. In the movie education is shown as the base for control. It portrays how the society is build from the education teaching the younger generation the way they have to act and think. So if they teach in the institutions a way of behaving and show them what they consider to be good or bad, then in the future everyone would follow the same beliefs and hence they have the control of everyone.
7. In the fresh scene we can appreciate a group of double-hammer marching perfectly in order. This whole metaphoric scene what is trying to teach us is how education control us to be a “perfect” person without any error, and with a same style of life and that the meaning of being different means to be a wrong person. 
   
8. The children falling into the meat grinder is a visual metaphor that represents how education kills every different thought from what the government and schools wants, leaving only a human body, a robot that only express and repeat one idea. What education do to children is burning their brains and every thing that is different. 
9. In the Cambridge dictionary the wall is defined as a structure made of brick or stone that divides different areas. In the Pink Floyd film the wall represents is how society is divided between the good persons and the bad ones, where education is a key point from these division. Another way of seeing this powerful concept this that “we are just another brick in the wall”, where every human being represents a brick in that wall, representing only one thing, the same thing, the same idea, hiding our differences,and making it impossible to us to build our own wall and creating our wall, full of knowledge and diferents ideas.
   

Work done toghether with Tomas Busquets and Sebastian Varisto

Nous avons visité l'Alliance Française

   Le Mardi 17 Mai nous sommes allés à L'Alliance française. L'Alliance était extraordinaire et ancienne à l'extérieur mais très moderne à l'intérieur.

Nous alions à la médiathèque, nous faisons des activités avec les livres, les CD, les DVD et les VD. Il y avait beaucoup de matériels anciennes. La médiathèque était grande et magnifique avec beaucoup technologies.

Après nous avons visité une salle de classe pour regarder les vidéos éducatives avec la coordinatrice. On a eu une classe de compréhension de l´orale et on a répondu des questions.

Plus tard, nous avons obtenu un souvenir avec un stylo et un magazine. Enfin, nous sommes retournés au collège. 

Bref, dans l'Alliance, nous avons passé une tranquille, et belle journée oú nos avons eu la possibilité de apprendre un peut plus de la culture Française.

Salle de Classe

Médiathèque 

L'extérieur de l'Alliance

Eyewitness Accounts

    An eyewitness, is someone who actually sees some act, occurrence, or event and can give a first hand description of it. Eyewitness accounts are mostly considered by the people as a more reliable and credible source than hearsay accounts. This is due to the fact that for being a first-hand account, meaning that after all the person was there and saw what actually happened, is more trustworthy than second-hand accounts, which often distort the event while this is being told or re-told. 

However, it should be stated that eyewitness accounts can be questioned and often considered unreliable and inaccurate, since the witness might give a wrong story due to many reasons. Observation is based on the five senses, therefore, if one of this is impaired the accuracy would be affected, hence the credibility of an eyewitness will be lessened. Moreover, there are different factors which might affect and eyewitness. Firstly, the context of where and when the observation takes place will affect what people see and hear, for example if its night or day, the weather condition, the distance from the event, if there is any obstruction, etc. Secondly, the perception, expectation and memory would also influence and observer, the memory reconstructs an observation, then this would be based on its pre-existing experience, knowledge, expectation and belief. Thirdly, the point of view of the eyewitness will affect his observation, people are not objective and neutral, consequently their observations would tend to be distorted due to their biased and prejudice view. Lastly, the prior knowledge and expertise will also affected, the more you know about a certain topic or event the better you can shape your account, and so you add more credibility to an account.