BIO 2300 STUDY GUIDE 1 (Spring 2001)

Mendelian genetics Lethal allele Blending inheritance

Pleiotropy Particulate inheritance Epistasis

Gene Agouti Cross-pollination

Genotype Sum rule Closed flower

Phenotype Product rule F₁

Chi square F₂ Chance deviation

Allele Null hypothesis Locus

Chromosomes Homozygous Loci

Dominant Eukaryotic Heterozygous

Recessive Prokaryotic Trihybrid cross Punnett square Chromatin Transmission genetics

Monohybrid Heterochromatin Mitosis (all stages)

Dihybrid Euchromatin Cytokinesis

Backcross Centromere Independent Assortment Test cross Kinetochore Reciprocal cross

Metacentric Incomplete dominance Acrocentric

Codominance Telocentric ABO blood groups

Contrasting trait Homologous chromosomes Pisum sativum

Homologue Wild type Segregation

Quantitative trait Polygenic Additive alleles

Mean Variance Standard Deviation

Heritability Additive variance Artificial Selection

Chap.1 pgs. 1-14.

Chap.2 pgs. 17-39.

Chap.3 pgs. 45-64.

Chap.4 pgs. 77-91.

Chap 5 pgs 115-126.

Chap.2: 4, 6, 7, 8, 10, 14, 16.

Chap.3: 1, 2a-c, 5-10, 14, 16, 18, 19, 23, 24

Chap.4: 1, 2, 4, 6, 7, 10, 16, 18, 20.

Chap. 5: 1-4

1. Distinguish between genotype and phenotype.

2. Why is the testcross used? How many different test cross outcomes are possible for peas that express two dominant traits (yellow and round seeds)? What phenotypic ratios are expected for these test cross results?

3. A given gene is determined to be a multiple allelic system with seven distinct alleles. How many genotypes are possible in this system?

4. In a cross AaBbCcDDEe x AaBbCcDdEE, what proportion of the progeny will be characterized by the genotype AABbCcDDEe? By the genotype AaBBCCDdee?

5. Distinguish between dominant versus recessive lethal alleles.

6. If F1 Yellow-seeded pea plants (produced from homozygous yellow and green-seeded parentals) were crossed to green-seeded plants, what proportion of the progeny would be expected to have yellow seeds? If F2 yellow-seeded plants were bred to green-seeded plants, what proportion of the yellow-seeded F2 plants would produce only yellow progeny?

7. A strain of dark brown mice was crossed to a strain of light brown mice. All F1's were dark brown. In the F2, 42 were dark brown and 15 were light brown. Are these results consistent with the Rule of Segregation? Use a Chi-square test to check.

8. The 42 dark brown mice from question 7 were crossed with light brown mice. Thirty of these mice produced litters composed of both dark and light brown mice, while twelve produced only dark brown mice. Is this consistent with the Rule of Segregation? Use the Chi-square to check.

9. For a complete dominant system involving the cross AaBbCcDd x AabbCcDD, what proportion of the progeny will show all four dominant traits?

10. How many phenotypes are possible from a cross between individual pea plants that are heterozygous for all of Mendel's seven traits? How many genotypes? How many gametes?

11. List the phenotypic ratios expected for an example of: (a) dominant epistasis; (b) recessive epistasis; (c) complementary gene action. How do these ratios differ from other departures from the typical dihybrid ratio involving two characters that both show complete dominance?

12. In cattle, the polled condition (allele A) is dominant over the horned condition (allele a). Coat color, however, is an incomplete dominance system that produces black (BB), brown (Bb), and white (bb) phenotypes. Describe the dihybrid phenotype. How many phenotypes result from a dihybrid cross? What is the phenotypic ratio of the F2's? What is the genotypic ratio? How does the genotypic ratio differ from that of a dihybrid system with complete dominance?

13. What is the difference between broad-sense and narrow-sense heritability?

14. What is the distinction between additive variance and dominance variance?