Essays on Homology

Transcriptional regulation of gene expression

Gene expression in eukaryotic cells is regulated at transcriptional, post transcriptional and translational levels (Tomizawa,  Lekstrom-Himes, and Xanthopoulos 17). Transcriptional control is the primary means of regulating gene expression. Eukaryotic transcriptional control functions at three levels: modulation of the activities of activators and repressors; variations in chromatin structure; and effect of activators and repressors on assembly of initiation complexes (Lodish et al. 368). Regulation of transcription initiation is the most widespread form of gene control in eukaryotes. However, in some cases, transcription may be attenuated and regulated at subsequent steps, such as during or after the transcription process (Cooper ...

1. Drosophila melanogaster has been used as a model organism to study human genetics because: it shares 75% homology with human diseases causing genes. Developmental genes are highly conserved in humans and Drosophila. Certain mutations can affect the same tissue in both the fly and human. Example of homologous genes includes: Hox gene, PAX 6, SALL1, TWIST 1, NKX2-5. Drosophila offers several other advantages that makes it an ideal organism for genetic diseases. The fly is easy to maintain and manipulate. It produces a large number of offspring’s and has a short generation interval that is very favorable ...

Human Immunodeficiency Virus, HIV is a retrovirus, which is a unique virus family consisting of RNA as the genetic material instead of DNA. This genetic material is surrounded by an envelope of lipoprotein. HIV differs structurally from other members of the family retrovirus. It is roughly spherical and has a diameter of around 120 nm. Human Immunodeficiency Virus comprises of two copies of non-covalently joined positive single-stranded RNA enveloped by a conical capsid that consist of the p24 viral protein, which is typical of lentiviruses. Lysine tRNA is reverse transcriptase that is magnesium dependent and is involved in the packaging of both ...