Dr. Fisher believes he has cloned a gene from one his tomato lines. Learning of

ID: 174562 • Letter: D

Question

Dr. Fisher believes he has cloned a gene from one his tomato lines. Learning of your prowess in molecular biology he has asked you to determine the type of gene that he has cloned. Describe characteristics of genes that would allow you to determine if Dr. Fisher's gene was transcribed by RNA polymerase I, II, or III? DNA sequence analysis suggests that Dr. Fisher has cloned potential regulatory regions from an mRNA encoding gene. A. Describe to how he could determine if the region contains promoter proximal elements (regulatory promoter sequences) or enhancer sequences. B. Describe how each type of sequence could work in promoting gene expression. A particular strain of yeast produces strains with a mutant cdc2 gene (or Cdk 1 gene), resulting in little to no production of the Cdc2 protein kinase (cyclin dependent protein kinase 1). Predict the result of such a mutation and explain your prediction. Describe how general transcription factors arc involved in transcription at a RNA pol II promoter and describe what each transcription factor does? Where is TBP found and what does it do? In a yeast cell, conditionally lethal mutations have been identified in the TFIIA gene. At temperatures above 43 degree C, the cell dies. Explain the impact of the defective gene and why it results in cell death at high temperatures.

Explanation / Answer

RNA polymerase are complex structure with many subunits around 8-14 subunits are found in each enzymes, each of RNA polymerase I, II, III has its own promotors and genes which their transcribe are unique, basing on the genes there are transcribing one can identify the RNA polymerase in action.

There are three types of RNA polymerases available, RNA POLYMERASE I, RNA POLYMERASE II, RNA POLYMERASE III, each of them are unique and specifically evolved to transcribe particular types of RNA only.

RNA Polymerase I:

It transcribe mainly 28S, 18S and 5.8S rRNAs, transcription of these rRNA is done by only RNA polymerase. It is mainly dedicated to for this function, these three rRNA are considered to be largest speices of rRNAs.

RNA Polymerase II:

Genes which code for proteins are transcribed with help of RNA Polymerase II,

RNA Polymerase III:

tRNAs and few other rRNAs (apart from 28S< 18S, 5.8S rRNA) are transcribed by RNA polymerase III, RNAs which are involved in splicing and protein transport.

Types of genes

RNA polymerase

5.8S, 18S, 28S rRNA

RNA polymerase I

snRNA

scRNA,

mRNA

RNA polymerase II

tRNA

RNA polymerase III