Bio 181, Fall 2005

Learning Objectives for Chapter 15, The Chromosomal Basis of Inheritance

Understand and be able to use the following terms:

Loci, locus	wild type	sex-linked gene	linked gene
parental types	recombinants	linkage map	map units
cytological maps	Duchenne muscular dystrophy	hemophilia	Barr body
nondisjunction	aneuploidy	trisomic	monosomic
polyploidy	deletion	inversion	translocation
Down syndrome	genomic imprinting

1. Describe the contributions that Thomas Hunt Morgan made to current understanding of chromosomal inheritance.

2. Explain why Drosophila melanogaster is a good experimental organism.

3. Define and compare linked genes and sex-linked genes. Explain why the inheritance of linked genes is different from independent assortment.

4. Distinguish between parental and recombinant phenotypes.

5. Explain why linked genes do not assort independently.

6. Explain how crossing over can unlink genes.

7. Explain how Sturtevant created linkage maps.

8. Define a map unit.

9. Explain why Mendel did not find linkage between seed color and flower color.

10. Explain how genetic maps are constructed for genes located far apart on a chromosome.

11. Explain what additional information cytological maps provide over linkage maps.

12. Explain how s gender is genetically determined in humans and the significance of the SRY gene.

13. Explain why sex-linked diseases are more common in human males.

14. Describe the inheritance patterns and symptoms of color blindness, Duchenne muscular dystrophy, and hemophilia.

15. Be able to predict the genotypes and phenotypes of sex-linked crosses, or determine the genotypes and phenotypes of parents of children with sex-linked traits.

16. Describe the process of X inactivation in female mammals. Explain how this phenomenon produces the tortoiseshell coloration in cats.

17. Distinguish among nondisjunction, aneuploidy, trisomy, triploidy, and polyploidy. Explain how these major chromosomal changes occur and describe the consequences.

18. Distinguish among deletions, duplications, inversions, and translocations.

19. Describe the type of chromosomal alterations implicated in the following human disorders: Down syndrome, Klinefelter's syndrome, extra Y, triple-X syndrome, Turner's syndrome, cri du chat syndrome, and chronic myelogenous leukemia.

20. Define genomic imprinting and provide evidence to support this model.

21. Give some exceptions to the chromosome theory of inheritance. Explain why extranuclear genes are not inherited in a Mendelian fashion and how they can contribute to disease.