Camila Chabi De Jesus

Ensaios

Ensaio opcional (10.03.17)

The central dogma of biology explains how the transmission of information occurs in biological systems. The information is stored in nucleic acids (genetic code) and according to dogma, the flow of this information occurs in the sense DNA>RNA>protein. However, in some cases the flow may occur in other directions, known as special flows. The transmission of information between DNA>DNA, DNA>RNA, RNA>protein is called replication, transcription and translation, respectively. The DNA and RNA are molecules composed of nucleotides and during translation three nucleotides (codon) encodes an amino acid, and different combinations can encode only one amino acid. On those groundsthe genetic code is universal and degenerate. Another interface that the central dogma allows to understand is about heredity, the same information is transmitted from cell>cell and organism>organism. Thereby, the genotype of each individual is determined by the genetic characteristics of their descendants. All this understanding about the genetic code, its transmission and universality, allows to reconstruct the evolutionary history between organisms of any taxon, through the stored information. Previously, the relations between the organisms were only about the phenotypic characteristics, not allowing studies of relationships with other ancestral and/or phylogenetically distant organisms.

The central dogma of biology explains how the transmission of information occurs in biological systems. The information is stored in nucleic acids (genetic code) and according to dogma, the flow of this information occurs in the sense DNA>RNA>protein. However, in some cases the flow may occur in other directions, known as special flows. The transmission of information between DNA>DNA, DNA>RNA, RNA>protein is called replication, transcription and translation, respectively. The DNA and RNA are molecules composed of nucleotides and during translation three nucleotides (codon) encodes an amino acid, and different combinations can encode only one amino acid (ou não…. pouco claro). On those groundsthe (palavras juntas) genetic code is universal and degenerate. Another interface that the central dogma allows to understand is about heredity, the same information is transmitted from cell>cell and organism>organism. Thereby, the genotype of each individual is determined by the genetic characteristics of their descendants (confuso, e interações com o ambiente? ou mesmo com outros genes… ver genética quantitativa). All this understanding about the genetic code, its transmission and universality, allows to reconstruct the evolutionary history between organisms of any taxon, through the stored information. Previously, the relations between the organisms were only about the phenotypic characteristics, not allowing studies of relationships with other ancestral and/or (filogenia com base morfológica, ou seja, sob dados fenotípicos também estudam a relação filogenética, mesmo que de forma limitada) phylogenetically distant organisms.

Texto muito bem redigido embora com, na minha opinião, muitas generalizações
Corrigido por Victor Calvanese

Ensaio 1 (17.03.2017)

DNA replication and its influence on phylogenetic reconstruction methods

The methods used for phylogenetic reconstruction are based on the dichotomization of genetic information. This concept consists of how DNA replication occurs. Through the experiments in E. coli carried out by Meselson and Stahl (Meselson and Stahl, 1958), it was possible to demonstrate that DNA replication is of the semi-conservative type. However, this model does not allow phylogenetic reconstruction from other types of exchange of genetic information between phylogenetically distant organisms. An example of how this phenomenon can occur is through the transposable elements. These elements of transposition, or transposons, are fragments of deoxyribonucleic acid capable of moving from one region to another in the genome of a cell. Transposons are present in different organisms and have a huge influence on the evolution and composition of plant and animal genomes (Giordano et al., 2007). Globally, bacteria have a variety of transposons, they can encode virulence genes and these can be transferred to other bacteria as well as to the genome of their hosts. Thus generating a non-dichotomous phylogenetic relationship, difficult to interpret from studies based on phylogenetic trees.

Análise por Livia
Tomar cuidado com alguns vícios de linguagens que estamos presos como em "These elements of transposition, or transposons,". Este caso é um vício pois não se sabe se é outra coisa ou o mesmo nome/sinônimo.
Daria pra reescrever a frase iniciada em " Globally, bacteria have…" pois existe duas informações distintas nela.

Ensaio 2 (24.03.2017)

Genetic drift and natural selection can occur at the same time?

The neutral theory of molecular evolution is based on random processes of genetic mutation and drift. Largely independent of natural selection, contradicting Darwin's theory (King and Jukes, 1989). Mutations occurring in a genome of any organisms are infinite. Most of these mutations are deleterious or neutral. However, deleterious mutations are impossible to measure. A small percentage of the mutations can be adaptive. These mutations can be fixed or not in the population by natural selection. In some cases, it is possible to analyze the fixation of these mutations in populations over N generations. And try to explain the reasons that led to this phenomenon. Being that, in experimental evolution always the null hypothesis is that the changes are due to genetic drift. For drift is a constantly present force. However, one can not exclude the hypothesis that natural selection is also acting on the population.

REFERENCE
King JL, Jukes TH. (1969). Non-Darwinian Evolution. Science 164:788-97.

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