Time allowed: 2 hours Answer ALL questions in Section A, ALL PARTS of the question in Section B and ONE question from Section C.

Transcription

1 UNIVERSITY OF EAST ANGLIA School of Biological Sciences Main Series UG Examination GENETICS BIO-5009A Time allowed: 2 hours Answer ALL questions in Section A, ALL PARTS of the question in Section B and ONE question from Section C. Write answers to EACH SECTION in the Answer Grid or a SEPARATE booklet. The maximum number of marks available for your answers in SECTION A is 40 marks The maximum number of marks available for your answer in SECTION B is 30 marks The maximum number of marks available for your answer in SECTION C is 30 marks The TOTAL number of marks available for the paper is 100 Numbers in square brackets [ ] indicate the relevant mark applied to each part of the question. Notes are not permitted in this examination. Do not turn over until you are told to do so by the Invigilator. BIO-5009A Module Contact: Dr Colwyn Thomas, BIO Copyright of the University of East Anglia Version 1

2 2 SECTION A: MULTIPLE CHOICE AND SHORT ANSWER QUESTIONS Answer ALL questions [40 marks] Answer multiple choice questions in the answer grid provided and attach this to your booklet for Section A. Unless stated otherwise, all multiple choice questions have ONE answer. 1. In relation to human ABO blood groups, which of the following statements is false? [1 mark] a) I B is dominant to I O b) I A is dominant to I O c) I A and I B are codominant d) I A is recessive to I O e) I O is recessive to I B 2. The white (w) gene in Drosophila is X-linked. When white-eyed females are crossed with red-eyed males, which of the following is true of the progeny? [1 mark] a) The males and females both have red eyes b) The males and females both have white eyes c) The males have red eyes and the females have white eyes d) The females have red eyes and the males have white eyes e) Half of the males have red eyes and half of the males have white eyes 3. Chickens with genotype BB have black feathers and chickens with genotype bb have white feathers. BB x bb crosses result in heterozygotes with intermediate colour ( blue ) feathers. What phenomenon explains the feather-colour phenotype of the Bb birds? [1 mark] a) Complete dominance b) Partial or incomplete dominance c) Co-dominance d) Epistasis e) X-linkage Section A continues on next page/...

3 3 Section A continued Which of the following is not true about mouse embryonic stem cells? [1 mark] a) They are derived from the inner cell mass of the blastocyst b) Their genome can be modified as they undergo homologous recombination c) They are used in reverse genetics d) They are multi-potent e) They can be selected by adding antibiotics to the growth medium 5. Which of the following best describes genomic imprinting? [1 mark] a) Genomic imprinting is observed in vertebrates and it affects gene activity depending on the parent from which the allele is inherited b) Genomic imprinting is an irreversible epigenetic modification of DNA which correlates with the silencing of either the paternally or maternally inherited allele c) Genomic imprinting always involves maternally inherited alleles which are inactive in the offspring due to epigenetic modifications d) Genomic imprinting is a reversible epigenetic modification of DNA which correlates with the silencing of either the paternally or maternally inherited allele e) Genomic imprinting is involved in the regulation of growth and errors lead to Angelmann Syndrome and Prader-Willi Syndrome 6. Which statement about mutations in the Sonic Hedgehog (SHH) pathway is not correct? [1 mark] a) SHH requires cholesterol modification to be fully active. Therefore mutations affecting cholesterol biosynthesis have phenotypes similar to SHH pathway mutants b) Defects in SHH signaling during embryo development can lead to limb malformations c) Defects in SHH signaling can lead to cyclopia d) Midfacial defects can be induced by mutations in the SHH signaling pathway or by alcohol during pregnancy e) Defects in SHH signaling leads to premature fusion of the skull bones Section A continues on next page/... TURN OVER

4 4 Section A continued Which of the following is not true about Fragile X syndrome? [1 mark] a) 5 UTR of FMR1 gene contains CGGn repeat b) Loss of protein results in phenotype c) Repeat sequence codes for poly-glutamine d) More common in males than females e) Affected individuals often have mental impairment 8. Which disease is caused by a gain of function toxic RNA? [1 mark] a) Chronic Myeloid Leukaemia b) Myotonic Dystrophy c) Huntington s Disease d) Down Syndrome e) Turner s Syndrome 9. Triplet repeats can occur in which area of a gene? [1 mark] a) Coding exons b) 5 UTR or 3 UTR c) Intron d) Promoters e) All of the above 10. Which of the following model organisms for genetic research has a tetraploid genome? [1 mark] a) Drosophila melanogaster b) Xenopus laevis c) Mus musculus d) Arabidopsis thaliana e) Oryza sativa For all remaining questions in Section A, please use an answer booklet. Remember to attach your multiple choice answer grid to the booklet. 11. Polyploidisation has played a significant role in eukaryotic genome evolution. Define the term polyploidy and explain the differences between allopolyploidy and autopolyploidy. [5 marks] Section A continues on next page/...

5 5 Section A continued What are the main advantages and disadvantages of Next Generation Sequencing over first generation technologies? [5 marks] 13. Describe why calico/tortoise shell cats are usually female (but can occasionally be male) and the genetic basis for their characteristic fur pattern. [5 marks] 14. What is monosomy? Explain why is it extremely rare in humans? [5 marks] 15. Yellow mice have the genotype A A y. The A allele conditions wild-type (agouti) coat colour and the A y allele conditions yellow coat colour. Two yellow mice were allowed to breed. Explain why two thirds of progeny are yellow and one third are agouti. Draw a Punnett square to illustrate your answer. [5 marks] 16. People that are homozygous for loss of function mutations at the FUT1 locus (i.e. genotype fut1 fut1) exhibit the Bombay phenotype. Explain why the fut1 fut1 genotype is epistatic to any genotype at the isoglutinogen (I) locus. [5 marks] END OF SECTION A START YOUR ANSWER TO THE NEXT SECTION IN A NEW BOOKLET Section B begins on next page/... TURN OVER

6 6 SECTION B: DATA HANDLING QUESTION ANSWER THIS SECTION IN A NEW BOOKLET Answer ALL PARTS of this question [30 marks] 17. The genetics of flower pigmentation in Pisum sativum showed that two genes (A and B) are required for wildtype pigmented flowers. (a) When two pure breeding non-pigmented mutants (genotypes aa BB and AA bb) are crossed what would be the predicted genotype and phenotype of the F1 progeny? [3 marks] (b) The F1 progeny were allowed to self-pollinate and a large number of F2 progeny were scored. A statistical analysis of the data showed the segregation was consistent with a 9:7 ratio of pigmented:non-pigmented flowers in the progeny. What can be concluded from this analysis? Use a Punnett Square to demonstrate your conclusions. [12 marks] (c) What proportion of the F2 progeny would be of the genotype AaBb (highlight these in your Punnett Square). [3 marks] (d) A molecular analysis of the a and b mutant alleles showed they each contain a small genomic deletion of base pairs compared to the corresponding wildtype alleles (A and B). Describe a molecular genetic strategy that you could use to identify progeny of the AaBb genotype. Use labelled diagrams to illustrate the predicted results of your molecular analysis. [12 marks] END OF SECTION B START YOUR ANSWER TO THE NEXT SECTION IN A NEW BOOKLET Section C begins on next page/...

7 7 SECTION C: ESSAY QUESTION ANSWER THIS SECTION IN A NEW BOOKLET Answer ONE question [30 marks] 18. Describe the principle and molecular mechanism of gene drive and discuss one potential application. 19. Describe the mechanism of action of CRISPR genome editing technology. Using specific examples discuss the potential applications of genome editing technologies in agriculture and medicine. 20. Mutations in mitochondrial DNA cause a number of significant human diseases. Describe how the patterns of inheritance of mitochondrial diseases differ from nuclear gene mutations (autosomal and X-linked), and discuss the recent strategies that have been developed for germ-line therapy of mitochondrial diseases. END OF PAPER

8 UNIVERSITY OF EAST ANGLIA School of Biological Sciences Main Series UG Examination GENETICS BIO-5009A Registration Number SECTION A: Answer Grid (for Multiple Choice Questions only) Place a single cross in the appropriate box Question No. A B C D E Marks given Marks available