1. (a) Compare and describe the difference of gene structures in prokaryotes and
ID: 272584 • Letter: 1
Question
1. (a) Compare and describe the difference of gene structures in prokaryotes and eukaryotes (b) How would such difference effect the gene expression (transcription and translation) regulation in prokaryotes and eukaryotes? 2. The amount and/or activity of protein products produced in cells can be regulated at various stages of gene expression. Use examples to describe how it works at EACH of the following stages, respectively (a) transcriptional level; (b) posttranscriptional level; (c) translational level; and (d) posttranslational level. 3. You are studying a new operon in E. coli involved in phenylalanine biosynthesis. (a) How would you predict this operon is regulated (e.g., inducible or repressible by phenylalanine, positively or negatively, etc)? Why? (b) You sequence the operon and discover that it contains a short open reading frame near the 5-end of the operon that contains several codons for phenylalanine. What prediction would you make about the function of this leader sequence and the peptide it encodes? (c) What is this kind of regulation called and would it work in a eukaryotic cell? Why or why not?Explanation / Answer
Ans1:
a)
Genes are the functional regions of DNA and their ultimate role is to provide information for protein synthesis. Gene structure contains unique elements necessary for transcription of gene and its regulation. However, there are certain differences in gene structure in prokaryotes and eukaryotes :
b)
Different gene structure lead to different regulation of gene expression in prokaryotes and eukaryotes.
Due to presence of operon (group of genes), several genes are under single regulation and require less proteins for regulation. But in eukaryotes, each gene is under individual regulation.
Due to presence of only coding region, translation can be coupled to transcription in prokaryotes, but not in eukaryotes. This saves time and energy in prokaryotic gene regulation.
Regulation in eukaryotes takes place at transcription, RNA processing, and translational level. But in prokaryotic cells regulation takes place mostly only during transcription, as translation goes on simultaneously.
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