Download Mixed Questions

Module 3 Revision Questions
Short Answer Questions:
1. Why are plasmids lost through propagation of bacterial strains in a laboratory?
What is this process called?
2. All mRNA produced in bacteria is polycistronic. True or false and explain.
3. List the types of macrolesions.
4. What is an episome?
5. Define the terms permissive and restrictive conditions.
6. Frameshift mutations generally have little effect on the protein product. True
or false and explain.
7. What is the excinuclease?
8. What role does methylation play in protecting cells against the introduction of
foreign DNA?
9. What is Tn3?
10. What is a Hfr?
Medium Answer Questions:
1. Discuss the Col plasmids.
2. What is photoreactivation?
3. The following sequence shows a small segment of mRNA.
5’- AAC UGU GGG CCA –3’
Make the following mutations changing only the wobble position of the cysteine
UGU) codon and describe the type of mutation.
(a) silent mutation
(b) missense mutation
(c) nonsense mutation
4. The greatest genetic exchange occurs between F+ and F- cells. True or false and
explain.
5. Compare genetic organization in prokaryotes and eukaryotes.
Large Answer Questions:
1. Compare and contrast the mechanisms of generalised and specialised
transduction.
2. Describe how to experimentally determine mechanisms of DNA transfer
occurring between organisms.
3. Describe the process of generating duplications, their loss and overall
importance in evolution.
4. Discuss, in detail, microlesions.
5. Discuss the process of transformation.
Additional questions
1. The size of microbial genomes varies greatly. Give examples of organisms and
genome sizes and compare this to a simple eukaryotic genome.
2. Describe the concept of plasmid incompatibility groups.
3.
4.
5.
6.
7.
8.
9.
What are R plasmids and give an example?
What are colicinogenic plasmids and give an example?
How are mutations introduced into DNA?
Describe photoreactgivation.
Explain mismatch repair.
What are the two types of excision repair and how does each work?
Describe how bacterial cells protect themselves against the introduction of
foreign DNA.
Some Mixed Questions
1. Why do mutations in bacterial genes have a more immediate effect than
mutations in eukaryotic system?
- prokaryotes have only one allele of each gene (i.e. haploid genome)
- any mutations have an immediate effect as there isn’t a second (functioning)
allele to compensate for the mutations
- mutations in prokaryotic genomes are immediately subjected to the pressures
of natural selection
2. Describe the genetic organisation of the bacterial genome and make comparisons
to the genetic organisation in eukaryotes.
3. Bacterial mRNAs need to be spiced. True or false and explain.
- False
- bacterial genes
4. All mRNAs produced by bacteria are polycistronic. True or false and explain.
5. Why are genes that are highly expressed oriented with respect to the diection of
replication?
6. What is a plasmid?
7. Why are plasmids lost through propagation of bacteria strains in a laboratory?
What is this process called?
8. What is a conjugative plasmid? Give an example.
9. What is an episome?
10. What is a colicinogenic plasmid?
11. Define the terms genotype and phenotype.
12. To what to the terms permissive and restrictive conditions refer?
13. Define the following conditions:
(a) auxotrophic
(b) prototrophic
(c) suppressor-sensitive
14. What are conditional mutations and give examples.
15. List the types of macrolesions.
16. Gene duplications are generally unstable. True or false. Explain.
17. What is a deletion macrolesion?
18. Which of the macrolesions is most important in evolution. Explain your answer.
19. Distinguish between duplications and insertions.
20. List the types of microlesions.
21. Frameshift mutations generally have little effect on the protein product. True
or false and explain your answer.
22. Define the following terms:
(a) Open reading frame
(b) frameshift
(c) codon
(d) stop codon
23. UGU is the codon for cysteine. Make the following mutations changing only the
wobble position and describe the type of mutation.
(a) silent
(b) missense
(c) nonsense
{Note: you may use the table on P9 and this table will also be provided in an exam if
required.}
24. What are transitions and transversions?
25. Silent mutations are more likely to arise from changes in the second nucleotide
position of a codon. True or false and explain.
26. What are transposable elements and give examples.
27. What are insertion sequences and what structural features do they have?
28. Define
(a) inverted terminal repeats
(b) direct repeats
29. How does transposition result in target site duplication?
30. Compare insertion sequences and composite transposons.
31. What impact do transposable elements have on the transfer of genetic material
between species?
32. Why is the exchange of genetic material between bacteria important in
evolution?
33. The processes of transformation, transduction and conjugation are very
different but share some aspects in common. Explain.
34. All bacteria are capable of transformation. True or false. Explain.
35. Define
(a) competency
(b) lysis
(c) transformation
(d) bacteriophage
(e) transduction
(f) conjugation
(g) pilus
36. Outline the process of transformation.
37. Outline the processes of generalised and specialised transduction.
38. Outline the process of conjugation.
39. The greatest genetic exchange occurs between a F+ and F- cell or Hfr and F- cell.
Explain.
40. Explain the terms lytic and lysogeny.