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Modern Genetic Analysis Chapter 2. The Structure of Genes and Genomes
Problems

1. | Draw a hierarchical classification diagram that shows the relationships of the terms eukaryote, prokaryote, haploid, diploid, nuclear genome, chloroplast genome, mitochondrial genome, plasmids.

2. | In a single cell of a plant leaf, how many copies are there of the nuclear genome, the chloroplast genome, the mitochondrial genome (choose your answers from "many," "two," or "one")? See answer

3. | What does the word homologous mean?

4. | The 3 billion base pairs of the human genome have been compared to the information content of 1000 textbooks. If the total length of DNA in the genome is 1 m, how big is a book in terms of a. Base pairs b. Length of DNA

5. | a.Which of the following have a mitochondrial genome: a fish, a moss, a palm tree, baker's yeast, a bacterium? b. Which of the following have a chloroplast genome: a diatom, a snake, a mushroom, the gut bacterium E. coli, mistletoe?

6. | List the forces that hold the DNA double helix together as a stable unit. See answer

7. | If thymine makes up 15 percent of the bases in a certain DNA sample, what percentage of bases must be cytosine? See answer

8. | If the G+C content of a DNA sample is 48 percent, what will be the proportions of the four different nucleotides?

9. | Draw a simple diagram of DNA that makes it clear what 5 and 3 ends are.

10. | Each cell of the human body (excluding gonads) contains 46 chromosomes. What are the ploidy level and haploid number? See answer

11. | How many DNA molecules are there in the nucleus of a human body cell?

12. | What are the different levels of DNA organization that result in the visible structures we call chromosomes?

13. | A certain segment of DNA has the following nucleotide sequence in one strand: What must be the sequence in the other strand (label its 5 and 3 ends)? See answer

14. | In normal double-helical DNA is it true that a. A plus C will always equal G plus T? b. A plus G will always equal C plus T?

15. | The most common elements in living organisms are carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. Which of these is not found in DNA?

16. | What is a gene? What are some of the problems with your definition?

17.

The genome of the bacterium Hemophilus influenzae is 1830 kb in size, and sequencing has shown it has 1703 genes.
a. What is the average spacing between the central points of genes?
b. If the average size of a coding region of a gene is assumed to be 1 kb, what is the average distance between genes?
c. What is in this region?
d. What proportion of the genome is expected to be introns?
e. What is the average space between coding regions?

See answer

18. | The gene for the human protein albumin spans a chromosomal region 25,000 nucleotide pairs (25 kb) long from the beginning of the protein-coding sequence to the end of the protein-coding sequence, but the messenger RNA for this protein is only 2.1 kb long. What do you think accounts for this huge difference? See answer

19. | DNA is extracted from cells of Neurospora, a haploid fungus (n = 7); pea, a diploid plant (2n = 14); and housefly, a diploid animal (2n = 12). If the DNA is separated using pulsed field gel electrophoresis, how many bands will be produced by each of these three species?

20. | Devise a formula that relates size of mRNA to gene size, number of introns, and average size of introns. See answer

21. | Progress in genome sequencing has led to the estimate that there is a 1.7 percent difference between the genomes of humans and chimpanzees. Assuming the two genomes are approximately the same size, how many nucleotide differences are there between these two species?

22. | In sentence form describe a. The difference between the purine and pyrimidine bases in DNA b. The difference between adenine and guanine c. The difference between cytosine and thymine

23. | Why are the 5 and 3 ends of DNA named thus?

24. | Draw the following pieces of DNA in the style of Figure 2-2b:

25. | How many bases are there in 2 kb of DNA?

26. | Using the figures of this chapter, estimate how many base pairs there are per complete turn of the DNA double helix.

27. | In a certain insect 2n = 18. If polytene chromosomes form exactly as they do in Drosophila, how many polytenes would be found per cell in the salivary glands? See answer

© 1999 by W. H. Freeman and Company. All rights reserved.