Reading 9

Question 1

What is a feature of gene regulation that is common to both prokaryotes and eukaryotes?

Answer 1

-DNA binding proteins influence the ability of RNA polymerase to initiate transcription

Question 2

What are three major differences in gene regulation between prokaryote and eukaryote cells?

Answer 2

1. Prokaryotes are organized into operons and are transcribed into single RNA while eukaryotes have their own promoters and are transcribed separately
   
   2. Chromatin structure impacts eukaryotic gene expression
      
      3. Presence of nuclear membrane in eukaryote and vs no nuclear membrane in prokaryote

Question 3

What are the two domains of the histones that make up the octamer core of a nucleosome?

Answer 3

1. Globular domain associates w/ histones and DNA
   2. Positively charged tail domain that interacts with negatively charged phosphate backbone of DNA

Question 4

How does the positively charged tail domain of a histone interact with DNA?

Answer 4

-the positively charged tail interacts with the negatively charged phosphate backbone

Question 5

What are three ways that the tails of the histones are modified when interacting with DNA?

Answer 5

1. Phosphate bone manipulation
   
   2. Methyl group manipulation
      
      3. Acetyl group manipulation

Question 6

What is the effect of methylation (addition of methyl groups) to the “tails” of eukaryotic histone proteins?

Answer 6

-addition or deletion of methyl groups, activating or deactivating transcription

Question 7

What is the effect of acetylation (addition of acetyl groups) to the “tails” of eukaryotic histone proteins?

Answer 7

-addition/ deletion of acetyl groups to histones stimulates transcription by preventing the formation of chromatin structure

Question 8

What is the effect of methylation (addition of methyl groups) to cytosine bases in eukaryotic DNA?

Answer 8

-addition of methyl groups to cytosine bases represses transcription, similar to acetylation of histones

Question 9

What is an enhancer in eukaryotic DNA?

Answer 9

-sequences capable of affecting transcription at distant promoters

Question 10

What factors affect the stability of eukaryotic mRNA?

Answer 10

-5’ cap and 3’ polyA tail