Chapter 19    Eukaryotic Genomes

Objectives

The Structure of Eukaryotic Chromatin

 1.  Compare the structure and organization of prokaryotic and eukaryotic genomes.

 2.  Describe the current model for progressive levels of DNA packing in eukaryotes.

 3.  Explain how histones influence folding in eukaryotic DNA.

 4.  Distinguish between heterochromatin and euchromatin.

The Control of Gene Expression

 5.  Explain the relationship between differentiation and differential gene expression.

 6.  Describe at what level gene expression is generally controlled.

 7.  Explain how DNA methylation and histone acetylation affect chromatin structure and the regulation of transcription.

 8.  Define epigenetic inheritance.

 9.  Describe the processing of pre-mRNA in eukaryotes.

10. Define control elements and explain how they influence transcription.

11. Distinguish between general and specific transcription factors.

12. Explain the role that promoters, enhancers, activators, and repressors may play in transcriptional control.

13. Explain how eukaryotic genes can be coordinately expressed and give some examples of coordinate gene expression in eukaryotes.

14. Describe the process and significance of alternative RNA splicing.

15. Describe factors that influence the life span of mRNA in the cytoplasm. Compare the longevity of mRNA in prokaryotes and in eukaryotes.

16. Explain how gene expression may be controlled at the translational and post-translational level.

The Molecular Biology of Cancer

17. Distinguish between proto-oncogenes and oncogenes. Describe three genetic changes that can convert proto-oncogenes into oncogenes.

18. Explain how mutations in tumor-suppressor genes can contribute to cancer.

19. Explain how excessive cell division can result from mutations in the ras proto-oncogenes.

20. Explain why a mutation knocking out the p53 gene can lead to excessive cell growth and cancer. Describe three ways that p53 prevents a cell from passing on mutations caused by DNA damage.

21. Describe the set of genetic factors typically associated with the development of cancer.

22. Explain how viruses can cause cancer. Describe several examples.

23. Explain how inherited cancer alleles can lead to a predisposition to certain cancers.

Genome Organization at the DNA Level

24. Describe the structure and functions of the portions of eukaryotic DNA that do not encode protein or RNA.

25. Distinguish between transposons and retrotransposons.

26. Describe the structure and location of Alu elements in primate genomes.

27. Describe the structure and possible function of simple sequence DNA.

28. Using the genes for rRNA as an example, explain how multigene families of identical genes can be advantageous for a cell.

29. Using a-globin and b-globin genes as examples, describe how multigene families of nonidentical genes may have evolved.

30. Define pseudogenes. Explain how such genes may have evolved.

31. Describe the hypothesis for the evolution of a-lactalbumin from an ancestral lysozyme gene.

32. Explain how exon shuffling could lead to the formation of new proteins with novel functions.

33. Describe how transposition of an Alu element may allow the formation of new genetic combinations while retaining gene function.