7/29/2019 Organization of Genomes Review Questions

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Organization of GenomesChapter 18 (pp. 334-342, 346, 349); Chapter 19 (pp. 359-361, 374-379).

PART A : Organization of Bacterial Genomes

1. Considering the bonds between base pairs, which of these DNA samples is most likely taken from the

bacteria collected at the mouth of the hot vent? Explain your answer.

2. Bacteria are very adaptable, as populations, due to natural selection, and as individuals, due to changesin their environments; describe.

3. Bacteria have about 100 times more DNA than in a virus, but about 1/1000 as much as the averageeukaryotic cell, contained mainly in one double stranded circular chromosome located in a dense regioncalled the nucleiod. Many bacteria also have plasmids. Draw the arrangement of nuclear material in abacterium.

4. Bacteria reproduce rapidly (example: E. coli can reproduce every 20 minutes) via binary fission, so theonly variation in offspring is due to mutation; explain.

5. If the genes of plasmids are not essential for the survival and reproduction of bacteria, what advantagedo they offer to bacteria with them? Provide examples by briefly describing F plasmids and R plasmids.

PART B : Genome Organization at the Chromosome & DNA Level

6. Describe the levels of chromatin packing, including in a description of key terms such as: histone

proteins, nucleosome, chromatin fibre, looped domain/nonhistone protein scaffold. Why is thispackaging essential for a eukaryotic nucleus?

7. Compare heterochromatin to euchromatin; how does heterochromatin play a role in gene expression?

8. About 97% of human DNA does not code for proteins or RNA such as?

9. What is repetitive DNA and how much of the genome does it comprise? How is repetitive classified?Distinguish between these classifications.

10. Satellite DNA is useful in DNA fingerprinting/forensics, and responsible for some genetic disorders suchas fragile X syndrome and Huntingtons disease. Briefly explain how this might work.

11. What is the function of satellite DNA (i.e., where is it found)?

12. A large portion of interspersed DNA consists ofAlu elements, families of similar sequences;

describe what is known and unknown about them.

13. Interspersed DNA is abundant and variable in location; much of it in mammals is mobile genetic

elements called transposons. Describe how transposons are able to jump in and out of genes.

14. What are multigene families? How did they arise? Provide an example of a family consisting ofidentical genes and non-identical genes.

15. What are transposons and retrotransposons? How might their action affect gene expression?

16. What are immunoglobulins? How do genes coding for immunoglobulins demonstrate selective deletion?