Download AP Biology - cloudfront.net

AP Biology
Chapter 11 – Regulation of Gene Expression
Reading Guide
Chapter 11
Regulation of Gene Expression
__________________________________________________________________________________
Go to the website http://www.dnaftb.org/dnaftb/1/concept/. Here you will find an excellent series of
tutorials for Chapters 9-12 of our book. Explore panels 29-33 to guide you through this chapter. Be
sure to click on the animation and problem links to get the complete info.
QUESTIONS – 11.1: Strategies of Regulating Gene Expression
1. List three examples of that illustration the regulation of gene expression in a cell or organism.
2. Distinguish between consitiutive and inducible genes.
3. Two general themes reoccur in how organisms regulate gene expression: negative regulation and
positive regulation. Differentiate the two.
4. What are viruses?
5. Are viruses considered ‘living’ organisms? Why or why not.
6. What types of nucleic acids may a virus contain?
7. Listed below are the steps in the lytic replication 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
8. How are the lytic and the lysogenic cycles different?
Page 1 of 7
AP Biology
Chapter 11 – Regulation of Gene Expression
Reading Guide
9. What is the advantage of a lysogenic cycle?
10. How is the replication of retroviruses different from that of other viruses?
11. What is the function of reverse transcriptase? Why was this considered such a violation of the
central dogma proposed by Watson and Crick?
12. 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.
QUESTIONS – Section 11.2: Prokaryotic Regulation of Gene Expression
Page 2 of 7
AP Biology
Chapter 11 – Regulation of Gene Expression
Reading Guide
1. Do prokaryotes have introns in gene sequences?
2. Do prokaryotes have a nucleus?
3. What is the primary way prokaryotes regulate gene expression?
4. What is the benefit of regulating a metabolic pathway at the level of gene transcription rather than
allosteric inhibition of the enzyme?
5. Are genes coding for proteins belonging to a metabolic pathway scattered throughout bacterial
genome or clustered together?
6. What is an operon?
7. Define:
REGULATOR GENE
PROMOTER
OPERATOR
STRUCTURAL GENE
Page 3 of 7
AP Biology
Chapter 11 – Regulation of Gene Expression
Reading Guide
8. Explain how the lac operon works:
a. If lactose is absent from the cell
b. If lactose is present in the cell
9. Explain how lactose acts as an inducer and why is the lac operon considered an inducible operon?
10. What proteins are coded for in the lac operon?
11. Why is it beneficial for a prokaryote to regulate a metabolic pathway in an operon model?
12. Explain how the trp operon works:
a. If tryptophan is absent from the cell
b. If tryptophan is present in the cell
13. Explain how tryptophan acts as a corepressor and why the trp operon is an example of a
repressible operon.
QUESTIONS – Section 11.3: Eukaryotic Regulation of Gene Expression
Page 4 of 7
AP Biology
Chapter 11 – Regulation of Gene Expression
Reading Guide
14. Summarize the differences in transcription between prokaryotes and eukaryotes.
15. Are all possible genes expressed in every possible cell in a eukaryotic organism? Why not?
16. In prokaryotes, does translation immediately follow transcription? Why?
17. 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
18. Define:
TRANSCRIPTIONAL
ACTIVATOR
TRANSCRIPTION
FACTOR
PROMOTER
ENHANCER
19. 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
Page 5 of 7
AP Biology
Chapter 11 – Regulation of Gene Expression
Reading Guide
20. Review the levels of chromatin structure.
heterochromatin.
Review the definition of euchromatin and
21. Explain DNA methylation. What is the effect of methylation?
22. What are two chemical modifications that can occur to histone proteins, and what are the effects of
each?
23. What is a Barr body?
structure?
How is a Barr body an example of genetic inactivation by chromatin
24. Define epigenetic inheritance.
25. Define genetic imprinting.
QUESTIONS – 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?
Page 6 of 7
AP Biology
Chapter 11 – Regulation of Gene Expression
Reading Guide
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.
Page 7 of 7