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PRIFYSGOL CYMRU
THE UNIVERSITY OF WALES
ABERYSTWYTH
INSTITUTE OF BIOLOGICAL,
ENVIRONMENTAL AND RURAL SCIENCES
SEMESTER 1 EXAMINATIONS 2008/
MODULE BS
APPLIED MOLECULAR BIOLOGY
Time allowed — 3 hours
Read these instructions carefully:
- Enter your name in the space provided at the top right of this page. Fold over and seal down the top right-hand corner as shown (adhesive strips are provided).
- Your reference/identification number should be written in the space provided at the bottom of the page.
- The paper is divided into two parts. Section A carries 50 marks, Section B carries 50 marks.
- Section A consists of short-answer questions, all of which should be attempted. Each question should be answered on the question paper and in the space provided. You may write answers for Section A in pencil if you wish.
This question paper thus becomes the answer book for Section A and it must be handed in complete. Make sure your name is on it and your reference/identification number.
- In Section B you are required to answer two questions. The answers for this section should be written in separate conventional answer books.
Candidate's Reference/
Identification Number
Section A (50 marks) Answer all questions. Tick the appropriate box where necessary, e.g [ ]
- Which statement concerning DNA polymerases is incorrect? ( 1 mark )
a. [ ] They catalyse the synthesis of DNA in the 5'-3' direction. b. [ ] They require a primer for synthesis to proceed. c. [ ] They do not require a primer for synthesis to proceed. d. [ ] Some DNA polymerases have exonuclease activity. e. [ ] DNA polymerases have no role in transcription.
- Which plant transformation technique is the most efficient? ( 1 mark )
a. [ ] Biolistic bombardment. b. [ ] Polyethylene glycol-mediated protoplast fusion. c. [ ] Microinjection. d. [ ] Agrobacterium- mediated. e. [ ] Electroporation of protoplasts.
- The Flavr Savr tomato has been modified genetically with ( 1 mark )
a. [ ] an antisense gene for polygalacturonase b. [ ] a gene conferring resistance to the herbicide glyphosate c. [ ] a gene which produces Bt toxin d. [ ] a viral coat protein gene e. [ ] a gene to enhance ripening.
- ß-galactosidase is encoded on the lac operon and is used as a reporter gene in gene cloning.
i) What function does this enzyme have in relation to the lac operon? (1 mark )
ii) What is the name of the colourless substrate it can hydrolyse to form a blue product? (^) (1 mark)
Turn Over
Above is a schematic of a region of prokaryotic DNA encoding a monocistron. The G represents the first base of transcription, the ATG encodes the first/start codon, TAA encodes the stop codon and the point X is the point at which the last base is transcribed.
a. Origin of replication b. 5’ untranslated leader c. 5' CAP d. Coding sequences e. 3’ untranslated tail f. polyadenylated tail g. promoter h. enhancer sequences i. terminator
Using the above letters / numbers answer the following.
i) What would you find in region 1? (1 mark) ii) What does region 2 represent? (1 mark) iii) What does region 3 represent? (^) (1 mark) iv) In which region will the Shine Dalgarno sequences be found? (^) (1 mark) v) In which region would the mRNA terminator sequences be found? (1 mark)
- In DNA-agarose gel electrophoresis a mixed population of DNA fragments can be separated. Outline the principles of this separation. ( 3 marks )
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- What is the definition of Tm? Give a simple equation to calculate the Tm of a primer_._ (2 marks)
Of the nucleotide structures given above
Answer (letter) i) which will be found in RNA? (1 mark) ii) which will be found in DNA? (1 mark) iii) can be used for DNA sequencing? (1 mark)
- Describe the principles behind nested PCR and explain why it is used? (2 marks)
- The stringency of in situ hybridisation can be increased by (1 mark)
a. [ ] raising the concentration of monovalent cations in solution b. [ ] increasing the concentration of formamide c. [ ] lowering the temperature d. [ ] increasing the duration of the hybridisation reaction e. [ ] adding digoxigenin.
- What does the term SDS-PAGE mean and why is SDS used? (2 marks)
Turn Over
- Delete the incorrect bracketed words from the statements below. (4 marks )
Wheat is a [diploid][hexaploid] crop plant, whose height has been [enhanced][reduced] by post- war breeding programmes, using gibberellin [biosynthesis][insensitivity] mutant genes that have been cloned by [transposon tagging][polymerase chain reaction].
- Somaclonal variation is (1 mark)
a. [ ] the genetic variation occurring in cells following prolonged periods of culture b. [ ] the genetic variation seen within individual cells of a plant c. [ ] essential for somatic embryogenesis d. [ ] suppressed by high levels of auxin e. [ ] an unavoidable consequence of plant tissue culture.
- Which of the following is NOT found on a T-DNA? (1 mark)
a. [ ] tmr. b. [ ] Vir operon. c. [ ] tms1. d. [ ] right border. e. [ ] tryptophan mono-oxygenase.
Turn over
Section B ( 50 marks)
Answer two questions. Answer each question in a separate booklet.
- Describe the functions of the DNA sequences that are involved in the initiation of transcription and translation in eukaryotes and prokaryotes. ( 25 marks )
- Compare and contrast the basic principles of cDNA and genomic library construction. Outline some of the specific uses of the different types of gene libraries. ( 25 marks )
- Provide an account of the principles of the polymerase chain reaction (PCR) and discuss briefly three examples of how it is used in research and/or medicine. (25 marks)
- Why was yeast adopted as a model organism, and what scientific advances have been achieved through its study? (25 marks)
- Describe how molecular genetics was used to isolate the gene responsible for the ‘Green Revolution’ in post-war wheat production. (25 marks)
- Imagine that you would like to construct an entirely new binary vector with which to transform plants using Agrobacterium tumefaciens. Describe which genetic components you could use and why. (25 marks)
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