1. Identify as many different signals as you can that are present in and around a typical eukaryotic protein coding gene in addition to the actual coding sequence. Briefly explain what each of these signals does.
2. Sickle cell anemia is an inherited disease that is particularly prevalent in individuals with Central African ancestry.
a. What is the nature of the genetic defect responsible for sickle cell anemia.
b. How is that defect manifested at the protein level.
c. How does the genetic defect cause the shape change of red blood cells and cause the other symptoms characteristic of sickle cell anemia.
d. What mechanism has prevented the sickle cell gene from being reduced to a very low level in the population by early death of afflicted individuals. To find the answer for this question, you will need to look at the lecture notes (or text pages 566-567, which you will find difficult to follow without some background explanation).
3. Describe two very different mechanisms that can result in beta-thalassemia.
4. Describe as many different ways as you can in which mutations that are not contained within the protein coding sequence of a gene can alter its level of expression (hint: the answers are spread over several chapters of the textbook)
5. What was the earliest evidence suggesting the possibility of a one gene - one enzyme relationship. Roughly when was this evidence obtained?
6. Describe the interactions that allow an eye imaginal disc from a larval Drosophila with the vermillion eye mutation to form normal pigment when allowed to undergo metamorphosis in the abdomen of a larva with the cinnamon eye mutation.
7. Explain why the opposite experiment does not work (a cinnebar eye disc in a vermillion larva).
8. What is an auxotrophic mutation?
9. Explain how a group of mutatant strains that are all auxotrophic for the same nutrient can have mutations in different genes.
10. If you know the biosynthetic pathway for a particular nutrient, how would you determine which steps had been lost in individual mutant strains selected randomly from a collection of strains that are auxotrophic for the nutrient in question.
11. Propose a procedure for using auxotrophic mutants to determine the order of the blocked steps in a biosynthetic pathway whose details you did not know.
12. A collection of auxotrophic strains of Neurospora that all require tryptophan for growth has been found to involve mutations at a number of different genetic loci. Explain how mutations in different genes can lead to the same auxotrophic growth requirement.
13. What is a prion and what makes the concept of prions so controversial?
14. Explain the concept of genetic complementation as it applies to the individual steps in a metabolic pathway.
15. How can a wide range of variability, such as human hair color, be achieved genetically?
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