ucfsi.files.wordpress.com · Web viewDNA nucleotides, or deoxyribonucleotides, have a deoxyribose sugar that lacks an oxygen molecule at the 2′ carbon of the sugar molecule. Ribonucleotides,

*** This review should be used as supplement to your studies and is not all-encompassing. ***

PCB 3063 Exam 3 Review

Chapter 25

1. What assumptions must be met for a population to be in Hardy–Weinberg equilibrium?

2. Jean Manning, Charles Kerfoot, and Edward Berger studied genotypic frequencies at the phosphoglucose isomerase (GPI) locus in the cladoceran Bosmina longirostris (a small crustacean known as a water flea). At one location, they collected 176 of the animals from Union Bay in Seattle, Washington, and determined their GPI genotypes by using electrophoresis

Genotype Number

S1S1 4

S1S2 38

S2S2 134

Determine the genotypic and allelic frequencies for this population.

3. Most black bears (Ursus americanus) are black or brown in color. However, occasional white bears of this species appear in some populations along the coast of British Columbia. Kermit Ritland and his colleagues determined that white coat color in these bears results from a recessive mutation (G) caused by a single nucleotide replacement in which guanine substitutes for adenine at the melanocortin-1 receptor locus (mcr1), the same locus responsible for red hair in humans. The wild-type allele at this locus (A) encodes black or brown color. Ritland and his colleagues collected samples from bears on three islands and determined their genotypes at the mcr1 locus.

*** This review should be used as supplement to your studies and is not all-encompassing. ***

Genotype Number

AA 42

AG 24

GG 21

a. What are the frequencies of the A and G alleles in these bears?

b. Give the genotypic frequencies expected if the population is in Hardy–Weinberg equilibrium.

4. Full color (D) in domestic cats is dominant over dilute color (d). Of 325 cats observed, 194 have full color and 131 have dilute color.

a. If these cats are in Hardy–Weinberg equilibrium for the dilution locus, what is the frequency of the dilute allele?

b. How many of the 194 cats with full color are likely to be heterozygous?

5. Tay–Sachs disease is an autosomal recessive disorder. Among Ashkenazi Jews, the frequency of Tay–Sachs disease is 1 in 3600. If the Ashkenazi population is mating randomly for the Tay–Sachs gene, what proportion of the population consists of heterozygous carriers of the Tay–Sachs allele?

*** This review should be used as supplement to your studies and is not all-encompassing. ***

Chapter 10

6. What four general characteristics must the genetic material possess?

7. How does an RNA nucleotide differ from a DNA nucleotide? Solution:DNA nucleotides, or deoxyribonucleotides, have a deoxyribose sugar that lacks an oxygen molecule at the 2′ carbon of the sugar molecule. Ribonucleotides, or RNA nucleotides, have a ribose sugar with an oxygen linked to the 2′ carbon of the sugar molecule. Ribonucleotides may contain the nitrogenous base uracil, but not thymine. DNA nucleotides contain thymine, but not uracil.

8. How does a purine differ from a pyrimidine? What purines and pyrimidines are found in DNA and RNA?

9. What different types of chemical bonds are found in DNA and where are they found?

10. DNA molecules of different sizes are often separated with the use of a technique called electrophoresis. With this technique, DNA molecules are placed in a gel, an electrical current is applied to the gel, and the DNA molecules migrate toward the positive (+) pole of the current. What aspect of its structure causes a DNA molecule to migrate toward to the positive pole?

11. One nucleotide strand of DNA molecule has the base sequence

*** This review should be used as supplement to your studies and is not all-encompassing. ***

illustrated below. 5′—ATTGCTACGG—3′ Give the base sequence and label the 5′ and 3′ends of the complementary DNA nucleotide strand.

12. If a double-stranded DNA molecule is 15% thymine, what are the percentages of all the other bases?

13. Heinz Shuster collected the following data on the base composition of ribgrass virus (H. Shuster, in The Nucleic Acids: Chemistry and Biology, vol. 3, E. Chargaff and J. N. Davidson, Eds. New York: Academic Press, 1955). On the basis of this information, is the hereditary information of the ribgrass virus RNA or DNA? Is it likely to be single stranded or double stranded?

Percent A G C T U

Ribgrass virus 29.3 25.8 18.0 0.0 27.0

Chapter 11

*** This review should be used as supplement to your studies and is not all-encompassing. ***

14. Describe the composition and structure of the nucleosome.

15. What is a chromosomal puff?

16. What are epigenetic changes and how are they brought about?

17. What is the difference between euchromatin and heterochromatin?

Chapter 12

*** This review should be used as supplement to your studies and is not all-encompassing. ***

*** This review should be used as supplement to your studies and is not all-encompassing. ***

18. List the different proteins and enzymes taking part in bacterial replication. Give the function of each in the replication process.

19. Why is DNA gyrase necessary for replication?

20. What similarities and differences exist in the enzymatic activities of DNA polymerases I and III? What is the function of each DNA polymerase in bacterial cells?

21. Why is primase required for replication?