MCB164S09+Practice+problems417key

MCB164S09+Practice+problems417key - MCB164 S09 Practice...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
MCB164 S09 1 Practice problem 4/09/2009 MCB164 practice problem set #3 April 17, 2009 These problems are taken directly from exams and in class exercises from previous years. Some are from homework problems and these are much harder. Those will be indicated here. 1. Explain why a nonsense suppressor mutation would be considered to be allele-specific but not gene-specific. Clearly indicate in your answer that you understand what a nonsense suppressor is. A nonsense suppressor allows read through of a mutation that generates a premature stop codon in a gene. It is typically a mutation in a tRNA gene that alters the anticodon loop so that it can basepair with the nonsense codon. This suppressor is allele specific because it can only suppress specific alleles mutated to have a stop codon. The suppressor is not gene-specific since it can suppress nonsense mutations in other genes . 2. You have identified 12 independent mutations affecting telomere maintenance in budding yeast (m1, m2, m3…m12). Mutations m1-m6 were generated in a MATa strain background and mutants m7-m12 were generated in a MATalpha strain background. The phenotypes of diploids generated from pair-wise crosses (m1…m6) x (m7…m12) are shown in the table below where “M” represents a diploid exhibiting a mutant phenotype and “+” represents a wild type phenotype. m7 m8 m9 m10 m11 m12 m1 M + + + + + m2 + + M + + + m3 M + + + + + m4 M M M M M M m5 + + + + + + m6 + + + + M M A) (6 points) Group mutants that are most likely to be alleles of the same gene based on the given data. M1, m3, m7; m2, m8; m6, m11, m12 M5 defines its own complementation group
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Practice problem 4/09/2009 B) (8 points) Based on these data, what can you infer about mutant 4? How could you test your hypothesis? M4 fails to complement all other alleles. It may be a dominant mutation. This can be tested by crossing m4 to wild type and looking at the phenotype of the diploid progeny . C) (3 points) What phenotype would you expect of the diploid formed by crossing m5 x m5? (assume you can create both MATa and MATalpha versions of this mutant) Mutant 3. Your little sister has a science fair project coming up and need your help. She has decided to demonstrate patterns of Mendelian inheritance by performing genetic crosses of flowering plants. Consider the genotypes and relevant phenotype below; B and C act independently to influence flower color. A dominant fertile a recessive male sterile, dominant bright petals B dominant red petals b recessive blue petals C dominant red petals c recessive blue petals, suppressed by D D dominant suppressor of c d recessive, no suppression of c a) Give the phenotypes for plants with the following genotypes: Aa bb CC Dd Fertile, Blue petals AA BB cc Dd Fertile red petals aa bb cc Dd Sterile blue petals b) Perform a self-cross of Aa Bb Cc dd plants. What is the frequency of Aa bb cc dd progeny? ½ x ¼ x ¼ x ¼ = 1/128
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 8

MCB164S09+Practice+problems417key - MCB164 S09 Practice...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online