PeytonMorganGRQ23

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Dec 6, 2023

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GRQ #23- Mutations and alleles Read- Sections 4.1 and 14.1. If a specific term does not appear in the text, feel free to search for it in other resources (e.g. the web. S ection 4.1 1. Define dominant and recessive: A dominant allele produces a dominant phenotype in individuals with just one copy, but recessive alleles need both copies to express the recessive phenotype. 2. A gene product (e.g. protein) will not be produced if the gene carries a loss-of-function mutation. a. True b. False c. Depending on the nature of the mutation 3. A gain of function mutation can result in a null allele. a. True b. False 4. Will an excess of a gene product be detrimental or beneficial? Explain. Detrimental because large changes in the amount of a gene product can cause negative effects on the phenotype. 5. How many alleles must carry a gain of function mutation to confer a mutated phenotype in a diploid organism? a. 1 b. 2 c. 3 d. None 6. Might we expect to find many or only a few neutral mutations among the population? Explain. Many. Most evolutionary changes are caused by random neutral or nearly neutral mutations. These compound over time to produce new phenotypes.

7. Give an example for a molecular event that can result in a null mutation. A LOF mutation that leads to no gene product being produced. 8. Give an example for a molecular event that can result in a hypomorphic mutation. A LOF mutation that only leads to reduced expression. Section 14.1 9. How are germline mutations differ from somatic ones? Which ones are expected to have an impact on following generations? Somatic mutations are mutations in any cell other than germ cells, whereas germline mutations occur in germ cells. Germline mutations will have effects on future generations. 10. Will a loss of function X-linked mutation ever confer a mutated phenotype, if carried on one of the X chromosomes of a female? Explain. No, because female organisms have two copies of the X chromosome. 11. Will you expect a null mutation in the gene encoding DNA Polymerase to be a lethal mutation? Why? Yes, because DNA would not be able to be replicated, so new cells could not be produced and damaged ones could not repair. 12. T4 is a bacteriophage (virus that infects bacteria) that normally grows on E. coli plates. T4 rll mutants grow on E. coli strain B but not on E. coli strain K-12. What type of mutations do the rll mutants carry? LOF mutation 13. What is a permissive temperature and what is a restrictive one? At a permissive temp, the mutated gene functions normally, but at a restrictive one it loses function. 14. Conditional lethal mutations have been instrumental in biological research over the years, especially in research of embryogenesis- development of tissues and organs in the embryo. What is the advantage of using this specific type of mutations? Conditional means that expression is changed only if an inducer is present. This gives researchers control over when a gene is expressed, so different effects can be observed. 15. In an imaginary diploid organism, gene D encodes for a protein that makes Duke hats. For a given time, each copy of the gene makes 500 hats. As the number of Duke fans is limited, for a given time they need only 300 hats. A heterozygote for a null mutation in gene B will be able/ not be able to provide the required hats (circle the correct answer). Explain

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