Lecture 37: Eukaryotic transcriptional control
Note that these questions also include material from chapters 12 and 17. In addition, some ask about specific parts of the current lecture in a broader context.
1. Distinguish between euchromatin and heterochromatin in a manner that makes it clear that you know what each is and how they differ.
2. Dinstinguish among the three types of eukaryotic RNA polymerases in terms of the function of each.
3. What are the major differences in organization between prokaryotic and eukaryotic genes.
4. Summarize the main differences in gene expression at the level of a mature functional protein in eukaryotic vs. prokaryotic cells. (What additional steps are required in eukaryoties and opposed to prokaryotes?)
5. What roles are played by the three major types of RNA molecules produced by the three types of eukaryotic RNA polymerase?
6. What is the role of the TATA box in promoters that have one?
7. What role is played by the TATA-binding protein in the initiation of transcription from promoters that contain a TATA box?
8. Describe the processing that must occur to convert the initial transcript of an eukaryotic gene to a functional messenger RNA.
9. What are the features that distinguish enhancer sequences from functional parts of the promoter, such as the CAAT box and the TATA box?
10. How is a distant enhancer site believed to activate transcription? (What mechanism allows it to exert its effect over a considerable distance?)
11. Enhancers are sometimes found to be located within the introns of the gene whose expression they regulate. Why does the removal of the intron during message splicing not interfere with the regulatory function of the enhancer?
12. What are the major components of the class II preinitiation complex and how is it assembled. What component is added first? What is the role of that component?
13. How does the relationship between transcription and translation differ between prokaryotic and eukaryotic cells?
14. What aspects of the overall life cycles of eukaryotic organisms make it necessary to have more complex controls over gene expression than are found in prokaryotic cells?
15. Identify the three different domains that a protein must possess as a minimum to function as a ligand-responsive transcription factor (for example, a steroid hormone receptor).
16. Methylation has been implicated in control of gene expression
a. What generalized relationship exists between DNA methylation and control of gene expression?b. What is the nature of the methylated sequence, and where is it methylated?
c. How would you determine whether a particular sequence was methylated or not in a particular tissue?
17. Explain how it has been proposed to utilize demethyulation in the treatment of genetic disease. What agent is used to achieve demethylation? Why is it not necessary to keep the agent continually present?
18. Enhancers are known to work at a distance of thousands of base pairs from the promoter whose transcription they enhance.
a. What is the actual distance between two points of a DNA double helix separated by 1000 base pairs.
b. Other than the fact that enhancers work at great distances, what other evidence do we have that a DNA double helix is capable of being bent in the manner shown in figure 19.13? (Hint: the answer does not come from this lecture).
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