Maila Beyer

Ensaio opcional 10 março 2017

One of the wonders of the Central Dogma of Molecular Biology is its universality, in fact the universality of the genetic code, which is the same for all organisms. This means that it is possible to compare all living things to each other. Despite it seems a simple and obvious idea, this is a big step for understand the tree of life and the beginning of life. If before, it was not possible to compare fungi with animals or plants with prokaryotes, due to the absence of ‘’something’’ in common, it is now. Nowadays, with a range of tools, it is possible to compare sequence of the human, of the bacteria that causes tuberculosis and sunflower.

Revisado por Filipe Gudin: Um dos primeiros pontos que podem ser abordados a respeito do teu texto é a formalização da sentença-chave. Como o tema central é a universalidade do dogma central, seria possível encerrar o período logo em “… is its universality.” e aí continuar a ideia em outra sentença, como “In fact, the universality of the genetic code can be seen in all organisms, enabling comparative studies.”. Os períodos estão objetivos e curtos, porém os achei um pouco repetitivos, sempre se referindo à comparação. É possível perceber isso pela presença do verbo “compare” em quase todos eles. Seria interessante explorar um pouco mais o por quê essa comparação é possível, comentando sobre o fluxo de informação ou sobre o própprio código genético, por exemplo. Por causa dessa repetição, senti que o período final não é uma conclusão, mas mais um exemplo relativo ao período anterior. Dessa forma, o texto terminou de uma forma suspensa, deixando o leitor esperando algo a mais para fechar o raciocínio.

Ensaio 1 17/03/2017

The replication of the DNA is made in a semi- conservative model. This mean that the double helix splits in two, and each of the strands serves as a model for a new strand. This seems pretty obvious, but actually it’s not, or batter saying was not. There where tree possible hypothesis that the DNA replications occurred, a conservative model, semi-conservative model and dispersive model. After the Meselson & Stahl experiment, it was clear that the DNA replication is made under a semi-conservative model. Basically the experiments of Meselson& Stahl, they cultured bacteria in a culture containing heavy and not heavy nitrogen, and in each generation observed the proportion of heavy and not-heavy nitrogen.

Revised by Deyvid Amgarten
The assay talks about the models of replication for the DNA molecule. However, a topic sentence is absent and this idea is not passed in the very beginning of the paragraph. There are some minor English typos, as in: "This mean" (This means) and "There where" (There were). I suggest the author to avoid sentences like "This seems pretty obvious…" in scientific text. Last, but not least, I missed some conclusion sentence in the text to sum up the text principal idea.

Ensaio 2 24/03/2017

Natural selection is one of the most popular terms in the field of evolution. Was postulated by Darwin as an explanation for adaptation and speciation [1]. Natural selection act as a selective force on mutation that appear in the phenotype and lead to adaptation. Leading to the nowadays patterns of diversity. However, would this be the only force acting on variability? The answer is no. Kimura demonstrate that in the molecular level many mutations occur, generating high variability. This nucleotide substitution happens all the time, and most of the times they are natural [2,3]. That means that they aren’t perceived in the phenotype. So they not necessarily are adaptation, but are a kind of variability, more common than Natural Selection.

Reference:

1. Darwin, C. 1859. On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. London: John Murray Albemarle Street.
2. Kimura, M. 1968. Evolutionary Rate at the Molecular Level. Nature, 217:624.
3. Kimura, M. 1991. The neutral theory of molecular evolution: a review of recent evidence.. Jap. J. of Genetics

Comentários por Bruno F. Lima (31/03):
Olá Maila. Seguindo os métodos e critérios de correção estabelecidos pelo Daniel nas aulas anteriores, identifico os seguintes pontos a serem melhorados no seu ensaio:
1) Eu realmente não entendi muito bem o que você quis dizer na terceira sentença. Talvez se você usasse outra ordem de palavras, ficaria mais fácil identificar o seu ponto nesta frase.
2) A segunda sentença deve começar com um "It" ("It was postulated…"). Ainda na segunda sentença, como o Daniel falou, ficaria melhor se você não usasse os verbos na forma passiva ("postulated").
3) Acredito que seria necessário apenas uma vírgula para separar as sentenças 3 e 4; além disso, houve muita repetição da palavra "lead" e "leading".
4) Como o Daniel também falou, na escrita científica é preferível evitar o uso de questões ("Would this be the only force acting on variability?") e acredito que a forma correta seria "Would that be the only force..?.".
5) Acredito que na sentença 8, você queira dizer "neutral" ao invés de "natural".
6) Novamente, na última sentença, não entendi inteiramente o que você quis expressar. Talvez substituir ou mudar a ordem das palavras seja uma solução.
Gostei bastante do seu parágrafo pois você usou sentenças curtas e expressou muito bem o ponto principal (topic sentence) da sua ideia. Ficou bem clara a exposição do conceito que você quis trabalhar.
Espero que minhas sugestões te ajudem a melhorar seus textos!
Abraços, Bruno 

Ensaio 03 31/03/2107

Publico alvo: turma de pós-graduação

Neutral theory demonstrated that the majority of molecular changes occur randomly, being fixed or lost in a given population [1]. This process of fixation or loose of the alleles is caused under an effect known as Genetic Drift. Some peculiar cases can make drift effects stronger or weaker, and one of these cases is the effective population size. Effective population size determinate the rate of change in the genetic composition of a population, in other words is the number of individuals capable of passing their genetical diversity to the next generation[2]. The larger the effective population size is, lass influence of the genetic drift is acting on the population. This happens because in small population any change in gene frequencies promptly leaves to fixation or loose while in big population the changed allele remains for several generations [3].

Ref

1. Kimura, M. 1991. The neutral theory of molecular evolution: a review of recent evidence. Japanese Journal of Genetics 66: 367-386.
2. Charlesworth, B. 2009. Effective population size and patterns of molecular evolution and variation. Nature Reviews Genetics 10 : 195-205
3. Ellstrand, N.C & Elam, D.R. 1993. Population genetic consequences of small population size: Implications for plant conservative 22: 217-242.

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