BIO00009C Examination Candidate Number: Desk Number: University of York Department of Biology B. Sc Stage 1 Degree Examinations 2016-17 Genetics and Evolution Time allowed: 1 hour and 30 minutes Total marks available for this paper: 50 · Answer all questions in the spaces provided on the examination paper . The marks available for each question are indicated on the paper . A calculator will be provided For marker use only: 1 2 3 4 5 6 7 8 9 10 11 12 For office use only: Total as % page 1 of 8
BIO00009C Answer all questions in the spaces provided 1. Describe the experiment that identified the human cdc2 gene. (4 marks) Yeast cdc2 mutants were grown in permissive conditions (1 mark) and transformed with a plasmid library of human genes (1 mark). The transformed cells were shifted to a restrictive temperature, where only the cells transformed with copy of the human cdc2 genes grew (1 mark). These plasmid rescue experiments showed that the human cdc2 gene could complement a mutation in the yeast cdc2 gene (1 mark), this occurred because the cdc2 genes in yeast and humans are highly conserved. 2. Wild-type Antirrhinum plants have red flowers. Seven white flowered mutants were identified by mutagenesis. The mutants were crossed to each other and wild-type (WT). The flower colour of the progeny was recorded and presented in the table below. mutant a mutant b mutant c mutant d mutant e mutant f mutant g WT red red red red red red red mutant a white red white red white red red mutant b white red red red white white mutant c white red white red red mutant d white red red red mutant e white red red mutant f white white mutant g white a) Why were all the mutant lines crossed to the wild type line? (1 mark) To test whether or not the mutations were recessive page 2 of 8
BIO00009C b) Write down the complementation groups you have identified. (3 marks) (ace) (b fg) (d) c) How many genes have been identified with roles in production of red flowers? (1 mark) three 3. Mimulus cardinalis produces red flowers. Mutagenesis screens have identified recessive mutations that generate yellow and orange flowers. A yellow flowered mutant line was crossed to an orange flowered mutant line. Flower colour in the F2 generation segregated in a ratio of 9 red: 4 yellow and 3 orange flowers. Draw a simple diagram of the biosynthetic pathway that generates the red flower colour that is consistent with this ratio. (3 marks) Answer (other explanations are possible): yellow y orange 0 red 4. What did comparative genomics reveal about the number and distribution of genes in E. coli? (3 marks) Comparative genomics revealed that E. colihas a core genome of about 3000 (1 mark), This analysis also indicated that there were many other genes represented in the genomes of a diverse set of strains (1 mark). It was also revealed that some genes, or