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Unformatted text preview: In the following problems, please indicate the type of mutation the statement describes: 1. (4pts) An individual cell homozygous for a mutant allele of the gene for phenylalanine hydroxylase contains no detectable activity for that enzyme. null mutation (will accept loss of function) 2. (4pts) If the cell homozygous for a different mutant allele of the same gene contains ~20% of the enzyme activity. Hypomorphic or leaky mutation 3. (4pts) A mutation that occurred in a plant petal. Somatic mutation 4. (4pts) Site-directed mutagenesis is used to change a codon from AAA (lysine) to AGA (arginine) in a gene encoding DNA gyrase, but the phenotype is still wild type. Neutral or synonymous mutation (2pts for missense mutation) 5. (4pts) A prototrophic yeast strain is obtained after mutational treatment of an auxotroph. The prototroph is crossed to a wild-type strain. Some progeny were auxotrophic. The change to prototrophy was caused by a extragenic suppressor mutation (will accept suppressor mutation for full credit; intragenic suppressor for 2 pts) 6. (4pts) A mutation results in an abnormally short protein. Nonsense mutation (I will accept frameshift) 7. (4pts) A heterozygous mutation in a ribosomal protein results in resistance. Gain-of-function mutation 8. (4pts) Explain the difference between enhancers/silencers and activators/repressors in the regulation of gene expression (No more than 2 sentences please). (2pts) Enhancers/silencers are cis acting sequences on the DNA where regulatory proteins (activators/repressors) bind to control the expression of a gene. (2pts) Activators/repressors are trans acting proteins that bind to cis acting sites (enhancers/silencers) to regulate transcription either positively or negatively. 9. (10pts) In what parent, and in what meiotic division could the nondisjunction causing an XYY individual have happened? a. (2pts) Parent Male or Father b. (8pts) Meiotic division- please draw the chromosomes undergoing meiosis I and meiosis II, the final gametes (6pts) and state which meiotic division the nondisjunction occurred at (2pts). (2pts) At the meiosis II division 8. (4pts) Explain the difference between enhancers/silencers and activators/repressors in the regulation of gene expression (No more than 2 sentences please)....
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This note was uploaded on 02/10/2010 for the course BIO NPB taught by Professor Furlow during the Spring '10 term at UC Davis.
- Spring '10