Question 1

Describe briefly the process by which steroid hormones affect gene expression.

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Question 2

Large numbers of micro-RNAs (miRNAs), also known as small temporal RNAs (stRNAs), have now been discovered in higher eukaryotes. Describe their characteristics and general function.

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Question 3

In E. coli, lactose (allolactose) and tryptophan both bind to repressor proteins as part of regulation of the lac and trp operons, respectively. Outline two differences between the behavior of these compounds and their associated repressor proteins, and describe their effect on the transcription of their associated operons. Why do these differences make physiological sense?

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Question 4

In some prokaryotes, some riboswitches act as transcriptional terminators, and they have similarities to rho-independent termination. What structural/sequence features would you predict to find in these riboswitches?

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Question 5

The operators in the lac operon include two 6-base-pair sequences that are palindromes separated by approximately nine residues. What is the significance of that in terms of binding of the repressor protein?

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Question 6

Match each of the operons with the type(s) of regulation present in that operon. Note that a given type can be used more than once, or not at all; also, a given operon may have more than one type of regulation.
Operon
Type or Regulation
(a) lac
(1) Activation
(b) trp
(2) Repression
(c) SOS
(3) Attenuation
(4) DNA rearrangement

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Question 7

Describe briefly the relationship between chromatin structure and transcription in eukaryotes.

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Question 8

What are three mechanisms of translational repression that are known to exist in eukaryotes?

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Question 9

"A protein with a gene that is actively being transcribed will be present in high concentrations." Why is this statement NOT true?

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Question 10

When analyzing transcriptional regulation by carrying out Northern blots, the RNA of housekeeping genes is typically examined in parallel with the gene of interest. Why would this be important?

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Question 11

Define each in one to two sentences: (a) heterochromatin; (b) euchromatin; (c) chromatin remodeling.

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Question 12

Describe in one or two sentences the role of each of the following types of proteins in the regulation of gene expression in eukaryotes: (a) basal transcription factors; (b) transactivators; (c) coactivators.

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Question 13

HMG proteins are named because they migrate rapidly in electrophoresis experiments (high mobility group) relative to other DNA binding proteins (particularly histones). What does this tell you about their amino acid composition?

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Question 14

Name and contrast the four different types of stem cells found in humans.

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Question 15

Describe briefly the general role of the protein products of each of the following types of genes in the embryonic development of the Drosophila: (a) maternal genes; (b) segmentation genes; (c) homeotic genes.

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Question 16

Explain how synthesis of ribosomal proteins in E. coli is regulated at the level of translation.

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Question 17

The lac operon includes the open reading frame for the permease (lacY) that is necessary for lactose import. How then does lactose get into the cell to activate transcription of the lac operon?

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Question 18

Describe three different mechanisms by which riboswitches can modulate mRNA.

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Question 19

DNA-binding transactivating proteins often possess a domain separate from their DNA-binding domains that serve as a docking site for interactions with the transcription complex, coactivators, corepressors, or even chromatin remodeling proteins, to regulate gene transcription. Describe three known kinds of such domains, and provide an example of each.

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Quiz 28: Regulation of Gene Expression