Gene Expression Essay Example | Topics and Well Written Essays - 2000 words

Gene Expression - Essay Example Before we start to Compare and contrast transgenic methods for manipulating gene expression between Drosophila and vertebrate animals let us discuss in brief about what is gene expression and function of genes Gene expression Genes exert their effects on the phenotype. The biological information is contained in the base sequence of DNA. Gene expression is the process by which this information is made available to the cell. This has been described by the central dogma. This states that information is transferred from DNA to RNA and RNA to a protein. During expression gene synthesis from mRNA molecule, into which information has been transferred in the form of genetic code. This synthesis of mRNA from of the strands of the DNA molecule is called transcription. The first step in gene expression is called transcription. Two strands of DNA separate, only one them act as template for the transcription into mRNA in 5’ïÆ'  3’ direction. This strand is non coding (antisense) strand and the other stand of DNA is coding strand (sense strand). This synthesis of polypeptide chain or a protein from mRNA is called translation.... Many genes express whenever the product is required and the expression is regulated. These genes are called regulated genes. Certain genes are expressed as a function of the interaction between RNA polymerase with promoter without any regulation. Such genes are called constitutive genes. They are constantly needed for cellular activities. Flow of genetic information from DNA to protein through RNA was described by crick as central dogma of molecular biology. The studies of bacterial genetics indicate that all genes not only specify the structure of an enzyme but some of them also regulate the expression of other genes. These genes are called regulator genes. This concept of gene regulation has been studied by Franois Jacob and Jacques monod in 1961.the relationship between the nucleotide sequence of mRNA and amino acid sequence that constitute a polypeptide chain is called as genetic code. Gene expression in Drosophila melanogaster Introduction Heterochromatin was originally defined visually as the heavily staining region seen in both the meiotic and interphase nucleus (hietz 1928). The contrast between the openness of euchromantin and the compactness of the heterochromatic implied that the euchromatic is the location of most gene function and led to the neglect of heterochromatin. However, it has become increasingly clear that the nuclear genome is more than a collection of autonomous DNA sequence and that a deeper knowledge of the structure of the nucleus and the chromatin, including the heterochromatin, will contribute to our understanding of the gene expression. In Drosophila melanogaster heterochromatin accounts for approximately 30 % of the genome. Its properties have been studied since the advent

Critical Analysis Research Paper Example | Topics and Well Written Essays - 750 words

Critical Analysis - Research Paper Example The first issue arises when the writer shows no issues associated with the black origin of Armand. To illustrate, the writer evidently points out that Armand had a ‘dark handsome face’ that did not disfigure. It is rather unsound to believe that Armand, in his entire lifetime, had no chance to know about his color, and that he never examined his skin color or compared it with the skin of others. Secondly, a man with such a strong and rather cruel personality did not seem aware about the race his mother belonged to. It is at the end of the story that he comes to know that his mother ‘who adores him, belongs to the race that is cursed with the brand of slavery’. The intention here is very clear; Armand is destined to be portrayed as an irrational human being. In other words, instead of race, the writer is trying to give stress on gender. The second technical fault comes in the fact that despite his ‘dark’ face, Madame Valmonde had no problem in al lowing their marriage. In addition, he had not loved her before, and he started loving her as if ‘stuck by a pistol shot’. Here, he decides to marry Desiree despite her obscure origin, and loves her blindly. Again as the child is born, He stops beating the black slaves he has. Thus, it becomes evident that Armand is presented as a cruel man who used to beat his slaves for no apparent reason. However, as Serafin, Bendixen point out, the birth of a child makes him give up his cruelty; and on the other hand, the female figures, despite his black complexion, started loving and trusting him blindly (188). The third point that hurts the reader is the fact that though Madame Valmonde and the nurse woman Zandrine immediately realize the fact that the child is black in complexion, both the parents; Armand and Desiree seem unaware of the color of the child until the child is three months old. It is rather irrational to believe that all other people except the child’s paren ts identified the issue. Here, again, the story loses its integrity by saying that Armand failed to identify the color of the child which is highly unlikely. For example, the moment Madame Valmonde sees the child she cries, â€Å"this is not the baby!† That means, she is totally surprised by the color of the baby. It is rather surprising that neither Armand nor Desiree could see this. However, for the sake of argument, one can say that while marrying a white woman, the purpose of Armand was to give birth to a white child that would ‘bear his name’. Here, one can make a rather reasonable assumption that though Armand was aware of his color and race, he married a white woman expecting a white boy. However, as he was disappointed by Desiree by giving birth to a black child instead, he loses all happiness. In the case of Desiree too, the negligence towards the color of the child she shows is surprising. Here, instead of claiming that she was unaware of the color, a b etter assumption would be that as she married a black man, she was expecting a black child. So, when the black child was born to a black father, she failed to see any dangers in it. In other words, she was unaware of the unreasonable ambitions of Armand. So, even when Madame Valmonde exclaims â€Å"this is not the baby† , Desiree believes the comment is about the growth of the child; not about the color.