Pract Prob Set 3A answers

Pract Prob Set 3A answers - Pract Prob Set 3A Bio61 Geoff...

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Pract Prob Set 3A Bio61 Geoff Lectures 19-22 1. Campbell chap 19 #1, 2, 4, 8, 9, 10-answers in book 1`. RNA pol II requires _____basal transcription factors__ to bind a promoter in a human cell. Transcriptional regulatory proteins interact with the _____transcription initiation _(RNA pol 2 with basal trxn factors)____________complex to stimulate or repress the rate of mRNA synthesis 2. Transcription factors are more likely to bind to a gene if it is wrapped around histones that are more ____acetylated_______ and its DNA is less ___methylated___________. 3. Why can changes in the primary sequence of a transcription factor affect the regions of DNA it binds to? If you change the amino acids of a DNA binding protein, it will not be able to make the same bonds with a specific DNA sequence since it will have different amino acid sidechains . 4. Dr. Mike Robiology has identified a yeast gene that is normally transcribed at a high rate only when the yeast is subjected to high heat. If the enhancers are removed from this gene, what would you expect under high heat conditions? The transcription rate would be much lower than usual and if this is the main type of gene expression regulation, then less of the protein would be expressed under high heat conditions by the yeast. 5 . If an mRNA is transcribed at a very low rate relative to other mRNAs but is found at high levels, what might this suggest about its regulation? This suggests that the mRNA may be stabilized by the cell so that it is not degraded very much and thus can accumulate. 6. The loveable liverwort has identical alleles of only one Cagrovarin gene and there is only one species of Cagrovarin mRNA. However, in the cell, one finds 2 species of protein-one has the size predicted by the coding sequence, and a second appears a little heavier. Explain how this can be??? The Cagrovarin protein may be regulated posttranslationally, meaning that some modification, ie a phosphate, is added to the protein to change its activity in the cell. Such an addition would make it heavier. However, this happens to only some of these proteins in the cell. Regulated spicing is not an option since there is only 1 species of mRNA present 7. When glucose is added to yeast cells growing on glycerol, the mRNA for the Ip gene is
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This note was uploaded on 05/01/2008 for the course BIO 61 taught by Professor Geoff during the Spring '08 term at Pacific.

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Pract Prob Set 3A answers - Pract Prob Set 3A Bio61 Geoff...

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