Flavia Akemi Nitta Fernandes

Ensaio Opcional - Aula dia 10/03/2017

The central dogma of molecular biology was proposed by Francis Crick in 1958 and then reanalyzed in 1970, after some misunderstanding in the scientific field. The main idea of the dogma is to explain the flow of genetic information in a biological system. One of its basic statements is that once genetic information is passed to the protein level it cannot be transferred to any other polymer (DNA, RNA or protein). Even though the core of the dogma is extremely simple, it has often been misunderstood due to the obscurity nature of some transfers. In this scenario, Crick reanalyzed his dogma in 1970, clarifying and reclassifying some events. He divided the genetic transfer events in three different categories: general transfers, special transfers and unknown transfers. The general transfers are the ones which occur in all cells (i.e. DNA→DNA, DNA→RNA and RNA→Protein). The special transfers, on the other hand, only occur in specific situations (i.e. RNA→RNA, RNA→DNA and DNA→Protein), such as the infection of a cell by a retrovirus. Finally, the unknown transfers are the ones which have never been identified before (i.e. Protein→DNA, Protein→RNA and Protein→Protein). This last category shows that is it impossible, from what we know, to transfer any information from the protein state to another polymer.

Correção por Jorge

Como previamente apontado, a ideia principal do texto está na segunda sentença. Sendo assim, esta poderia ser a primeira. Acho que talvez o ideal fosse juntar a parte histórica que está divida, combinando a primeira sentença com a que se inicia em "In this scenario, Crick…". Assim o texto se inicia com o que é o dogma, suas premissas e predições e então seu histórico. O restante do texto é muito claro e preciso, uma vez que primeiro você apresentou as três categorias e depois explicou cada uma separadamente. Na última linha, imagino que "it" e "is" estejam trocados acidentalmente. Eu também sugeriria que fosse usado "as far as we know" na última linha para reforçar a ideia de que há possibilidade da transferência, porém não está atualmente esclarecido como. Isso, claro, se houve essa intenção na sentença (como senti ao ler). Caso contrário, desconsidere.

Ensaio 1 - Aula dia 17/03/2017

The definition of species is one of the most controversial concepts in Biology. Even though the use of the word ‘species’ is widespread in the scientific literature, there are various acceptable definitions for this term. However, independently on the definition used by different authors, the main target of each study will determine the most preferable definition to be used. For instance, conservational studies usually focus on elucidating the diversity of taxa that can be found in a determinate location. Taxonomy studies, on the other hand, demand a more refined and detailed analysis, once the focus of this kind of research is to describe new species without the same urgency of the conservational ones. The different approaches chosen by each study represent the different scientific pressures the researchers are submitted to. Therefore, there is no right or wrong concept of species, only distinct definitions which explore different aspects of it.

Correção por Jorge

Novamente, acho o texto muito bem escrito e claro. Os seguintes comentários são pequenas sugestões para deixá-lo mais objetivo.
A sentença tópico está muito boa e precisa. Eu trocaria o "used" da segunda linha por "applied" para evitar a repetição da palavra que também é usada no final da oração (que, ao meu ver, poderia ser removida). "However, independently on the definition applied by different authors, the main target of each study will determine the most preferable definition".
Sugiro eliminar refined na linha 4, pois "refined and detailed" fica redundante. O resto da sentença poderia ser encurtada: "once the research focus is to describe…"
Finalmente, as orações finais deveriam ser idealmente divididas em duas, porém não consigo pensar em uma boa alternativa. Talvez elas estejam melhores juntas mesmo.

Ensaio 2 - Aula dia 24/03/2017

The neutral theory of molecular evolution postulates that evolution happens mostly in a stochastic way. A consequence of this statement is that genetic drift is much more common than natural selection as an evolutive force. This theory had a great impact in the scientific community once it was previously believed that natural selection was the main force taking place in the evolution of species. However, it is now known that almost all aminoacid and nucleotide substitutions take place due to genetic drift. The neutral theory of evolution does not annul the natural selection theory. Instead, it only conveys that various molecular events may have arisen and been fixated in a population by chance.

Analise por Livia
Texto claro a partir de uma frase tópico bem definida. No caso da avaliação de hoje, apenas um lembrete para que referencie as devidas colocações.

Ensaio 3 - Aula dia 31/03/2017

Target audience: Graduation students.

The effective population size (Ne) is an essential concept in the evolutionary study of populations. Evolutionary forces such as natural selection and genetic drift are extrictly dependent on the populations’ efective size. Genetic drift has a stronger effect in populations with smaller Ne. Therefore, alleles are randomly lost or fixated more rapidly (in fewer generations) than in populations with a bigger Ne. On the other hand, natural selection generates stronger consequences on bigger populations and is almost indistinguishable in smaller ones. However, only the response of the population to natural selection changes according to its effective size, while the strenght of the selection force keeps unchanged. For example, even though the fitness of a pair of alleles is the same in two different sized populations, the allele with better fitness might be lost by chance in the smaller one, once genetic drift has a stronger action in smaller populations. Then, knowing the effective population size is crucial to understand how to measure the evolutive forces in any biological system.

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