Download RG 11 - Regulation of Gene Expression

SLUH – Bio 431/AP Bio – Pham
Reading Guide 11
RG 11 – Regulation of Gene Expression*
*Adapted and modified from Robbyn Tuinstra’s work
11.1 – Strategies of Regulating Gene Expression
1. Distinguish between constitutive and inducible genes.
2. Examine Fig. 11.2, differentiate negative regulation and positive regulation.
3. What are viruses? Explain why they do not qualify as organisms.
4. Listed below are the steps in the lytic cycle of viruses. Put the steps in the correct order.
_____ Phage genome directs host cell to produce phage components (DNA and capsids)
_____ Self assembly of phage
_____ Bacteriophage attaches to host cell
_____ Host cell lyses releasing phage particles
_____ Hydrolytic enzymes destroy host cell’s DNA
_____ Phage injects DNA into host cell
5. Distinguish the lytic and the lysogenic cycles.
6. Speculate the advantage(s) of a lysogenic cycle.
7. Explain how the replication of retroviruses (like HIV) is different from that of other viruses.
8. Listed below are the steps in the replication of a retrovirus. Put the steps in the correct order.
_____ Attachment of virus
_____ Reverse transcription – Viral RNA used as template to produce minus strand of DNA
_____ Uncoating of single-stranded RNA genome
_____ Proviral DNA transcribed into mRNA; mRNA translated into proteins and may become
genome for next generation of viruses.
_____ Capsid proteins enzymatically removed.
_____ Virus enters host cell cytoplasm
_____ Integration – newly produced viral DNA enters nucleus, inserts into host DNA and becomes
provirus.
Section 11.2 – Prokaryotic Regulation of Gene Expression
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SLUH – Bio 431/AP Bio – Pham
Reading Guide 11
9. Explain – and provide the reason for – the primary/most efficient way prokaryotes regulate gene
expression.
10. Discuss the benefit of such method of gene regulation vs. than allosteric inhibition of enzyme
activity.
11. What is an operon?
12. Study Fig. 11.8, explain how the lac operon works.
a. If lactose is absent from the cell
b. If lactose is present in the cell
13. Study Fig. 11.9, explain how the trp operon works.
a. If tryptophan is absent from the cell
b. If tryptophan is present in the cell
14. Explain how tryptophan acts as a corepressor and why the trp operon is an example of a repressible
operon.
Section 11.3 – Eukaryotic Regulation of Gene Expression
15. Summarize the differences in transcription between prokaryotes and eukaryotes.
16. Are all possible genes expressed in every possible cell in a eukaryotic organism? Explain.
17. In prokaryotes, does translation immediately follow transcription? Why?
18. How does the presence of a nucleus allow eukaryotes to regulate gene expression differently than
prokaryotes? (Why can’t prokaryotes regulate gene expression beyond the transcriptional level?)
TRANSCRIPTIONAL CONTROL
19. Define:
TRANSCRIPTIONAL
ACTIVATOR
TRANSCRIPTION
FACTOR
PROMOTER
ENHANCER
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SLUH – Bio 431/AP Bio – Pham
Reading Guide 11
20. How is it possible that a promoter or enhancer can be located a long distance away from the start of a
gene?
CHROMATIN STRUCTURE, CHEMICAL MODIFICATION OF DNA AND GENE EXPRESSION
21. Explain DNA methylation. What is the effect of methylation?
22. Describe the two chemical modifications that can occur to histone proteins.
23. What is a Barr body? How is a Barr body an example of genetic inactivation by chromatin
structure?
24. Define epigenetic inheritance.
25. Define genetic imprinting.
Section 11.4 – Post Transcriptional Control of Gene Expression
26. List the various modifications that must be made to an mRNA before it can leave the nucleus.
27. How does alternative splicing of introns effect the final gene product?
28. What can hinder the transport of mRNA from the nucleus?
TRANSLATIONAL CONTROL
29. What determines how long a mRNA will remain in the cytoplasm?
30. Give an example of posttranscriptional control of gene expression.
POSTTRANSLATIONAL CONTROL
31. Why are some proteins not immediately active after synthesis? Provide an example.
32. What regulates the half-life of a protein in a cell? Give an example of a short-lived protein.
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