Ensaio Opcional (03/10/17)
One of the most remarkable characteristics of the genetic code is their capacity of redundancy, meaning that most amino acids can be encoded by more than one three-base pair codon. Nucleotide base substitution occurs at different rates and have different consequences; thus, changes in the third codon base are most frequent than substitutions in the first and second positions. Commonly, a change in the third position does not lead to changes in the encoded amino acid. On the other hand, changes in first and second positions are always critical -specially in the second-; since they can originate point mutations, by encoding a different amino acid or by the appearance of stop codons, that may result in the translation of non-functional proteins. Since codon degeneracy is a natural mechanism to protect the genetic information against mutations and it is present in all living systems, this variation in the frequency of substitution has allowed to recover the phylogenetic signal for the reconstruction of evolutionary relations of organisms.
Comentário por Pietro
De forma geral eu considero o ensaio muito bom. A escrita está direta; a maior parte das frases apresentadas são curtas e diretas. Também pude identificar a ideia sentença tópico no começo do ensaio. Eu sugiro que se divida a primeira e a última sentença do ensaio em duas para que a escrita fique mais direta. As demais sentenças do ensaio estão boas e de acordo com esse conceito de escrita.
Ensaio 1 (03/17/17)
Before cell division occurs, DNA must be duplicated in order that each one of the daughter cells holds a copy of genetic material. The mechanism by which DNA is duplicated is called replication, and it is a semi-conservative process. DNA replication is referred as semi-conservative, because of one DNA molecule are created two identical replicas; each one conserving an original strand and a new one, which is synthesized by adding nucleotides that complement the template strand. DNA replication is not bug free, and errors can lead to mutations that can trigger different genetic diseases. It is therefore, that cells have mechanisms to check and repair faults during and after replication. Different pathways for DNA repair are present in all extant lineages, and they are vital for maintain the accuracy of replication, and with that life prosperity.
Comentários por Stefany A. de Angelis:
Senti falta de uma frase introdutória. Algo como "No processo da Replicação genica[…]. Antes da divisão ocorrer[…]."
Nesta frase "DNA replication is not bug free[…]", eu escreveria: "This process is not bug free […]". Pois já está subentendido sobre o que o texto está falando, descrito anteriormente. Então para não ficar repetitivo, eu colocaria desta forma.
No mais, entendi perfeitamente!
Ensaio 2 (03/24/17)
Evolution is propel for four evolutionary process. However, it is usually associated with natural selection. That as result of the big influence of Darwin in the conception of the evolution theory. In this way, it can be difficult to think in evolution as result of other mechanisms than those pushed by environmental conditions. Between the forces that propel evolution, there are evolutionary forces more likely to occur. Genetic drift is an intrinsic mechanism that generates variation in the allelic frequency in a stochastic way. It is responsible of most of the genetic variations that we found in the genome. Those persistent variations can or cannot have effect in the fitness of the organisms. When they does not have an effect, they are neutral. It is important to highlight, that different evolutionary forces are not mutually exclusive. Therefore, a mutation originated by genetic drift could have a higher probability to be fix in the population when natural selection takes a role on it. That by acquisition of adaptive values.