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Agro 726:Molecular Plant Breeding Second Semester 2011/2012 Question Paper

Agro 726:Molecular Plant Breeding Second Semester 2011/2012 

Course:Master Of Science In Agronomy

Institution: Egerton University question papers

Exam Year:2012



EGERTON UNIVERSITY
UNIVERSITY EXAMINATIONS
SECOND SEMESTER 2011/2012
YEAR TWO EXAMINATION FOR THE MASTER OF SCIENCE DEGREE IN AGRONOMY
AGRO 726: MOLECULAR PLANT BREEDING


INSTRUCTIONS: Answer all questions

Question 1
(a) Prokaryotic structural genes are often organized into clusters that include genes coding
for proteins whose functions are related. Clearly illustrate the structure of the LAC operon
and explain the role of each of the three lac structural genes (5 Marks)

(b) How might the concentration of glucose in a mediun in which E. Coli is growing
regulate the level of cyclic adenosine monophosphate (cAMP)? (2 Marks)

(c) Is the CAP-cAMP effect on transcription of the LAC operon and example of a positive
or negative control? Give your reasons. (3 Marks)

(d) In eukaryotic cells, processing of the RNA product may be regulated at the stages of
modification, splicing, transport, or stability. Discuss (8 Marks)

Question2

(a) Two models of replication have been proposed for DNA replication: conservative or
semi conservative. Which models fits DNA replication and why? (2 Marks)
(b) During DNA replication. What is the function of DNA ligase and what is its mechanism
of action (2 Mark)

Question 3.
What are some of the fundamental differences, structurally or in mechanism in eukaryotic
and prokaryotic gene expression? (8 Marks)

Question 4.

(a) A successful PCR experiment often depends on designing the correct primers. In
particular, the Tm for each primer should be approximately the same. What is the basis of
this requirement?
(4 marks)

(b) The power of PCR can also create problems. Suppose someone claims to have isolated
dinosaur DNA by using PCR. What questions might you ask to determine if it is indeed
dinosaur DNA? (4 marks)

Question 5.

Restriction enzymes and DNA ligase play essential roles in DNA cloning. How is it that a
bacterium that produces a restriction enzyme does not cut its own DNA? Describe some
general features of restriction enzyme sites. What are the three types of DNA ends that can be
generated after cutting DNA with restriction enzymes? (8 marks)



Question 6.

(a) DNA polymorphisms can be used as DNA markers. What are the advantages and
disadvantages of RFLP, SNP, and SSR markers in genetic mapping studies? (6 marks)

(b) What is plant transformation? Explain the practical requirements of transformation
systems for plant improvement? (8 marks)







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