Lecturer: Dr. Raida Khalil
Faculty of Science
Internal Examiner:
Department of Biotechnology & Genetic
Engineering
Student Name:
Course Name: Molecular Biology
Section: 1
Date: 24th April. 2012
Student Number:
Course Number: 240386 2ND Semester: 2011/2012
Second Exam
Time: 9:10 am Duration: 50 minutes
Number of Pages: 3 Number of Questions: 2
Strictly Use the provided Space Mark:
only!!!
/20
‘ It is better to understand a little than to misunderstand a lot’
Q1:Choose the most correct answer( 15pts)
1. All of the following steps are performed by the enzyme transposase during
nonreplicative transposition of bacterial insertion sequences except:
a. excision of the IS element from the donor DNA molecule
b. introduction of staggered cuts into the target DNA molecule
c. ligation of the IS element to the target DNA
d. synthesis of DNA to fill in the single stranded gaps
2. Which of the following is not a mobile DNA element?
a. transposon
b. long terminal repeats (LTR) c. long interspersed elements (LINES)
d. insertion sequence (IS) elements
3. Which of the following mobile elements is a retrotransposon?
a. yeast Ty element b. bacterial IS sequence c.Drosophila P element
d. maize activator (Ac) element
4. SINES (short interspersed elements)
a. are approximately 300 base pairs long b. are LTR containing retrotransposons
c. are present in over 1 million copies in the human genome d. a and c e. all of the above
5. Mobile DNA elements likely contributed to the evolution of higher organisms by the
a. generation of gene families by gene duplication b. creation of new genes by exon shuffling
c. formation of more complex regulatory regions d. a and b e all of the above
6. All of the following properties about microsatellite DNA are true except:
a. consist of a repeat length of 1-13 base pairs
b. can cause neurological diseases such as myotonic dystrophy
c. can occur within transcription units
d. a and b
e. all of the above
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All the best , Dr. Raida W. Khalil
7. Which of the following class of repetitious DNA is most abundant in the human
genome?
a. simple sequence DNA b. non LTR transposons c. LTR transposons d. DNA transposons
8. Chromosome painting is a technique that involves
a. staining chromosomes with Giemsa reagent
b. hybridizing fluorescent probes to chromosomes
c. hybridizing radioactive probes to chromosomes d. a and b
e. all of the above
9. Which of the following is a typical feature of prokaryotic genes?
a. polycistronic messenger RNAs b. complex transcription units c. introns
d. a and c e. all of the above
10. All of the following statements about complex transcription units are true except:
a. can have multiple poly A sites b. can generate multiple mRNAs
c. can generate multiple polypeptides d. are common in bacteria
11. Loss of the 3’ to 5’ proofreading exonuclease activity of DNA polymerase in E.Coli
should slow the:
a.Rate of DNA synthesis but not affect its fidelity
b.Rate of DNA synthesis and its fidelity
c. DNA fidelity only
d. Non of the above
12 Which of the following enzyme(s) can remove or insert supercoil twists into circular
DNA?
a, Topoisomerases b. DNA Pol II c. Spliceosomes d. Helicase e. none of the above
13. The RNA primer is removed from the Okazaki fragment by:
a. DNA Pol I b. DNA Pol II
c. DNA Pol III d. RNA polymerase
14. A nick is missing a _________ while a gap is missing a __________.
a. Hydrogen bond; nucleotide. b. phosphodiester bond; nucleotide.
c. nucleotide; hydrogen bond. d nucleotide; phosphodiester bond.
15. Reactions that coupled when nick translation occurs:
a.polymerization an ligation b. Polymerization and 3’—5’ exonuclease
c. polymerization and 5’—3’ exonuclease d.polymerization,3’—5’ exonuclease and 5’—3’
nuclease
QII.(6 pts)
A. Use the following items to answer the next three questions.
a) Helicase
b) DNA gyrase
c) n' protein d) DNA polymerase
e) Primase
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All the best , Dr. Raida W. Khalil
1.Separates DNA strands by breaking hydrogen bonds (
2.Synthesizes RNA (
3.DNA polymerization (
)
)
)
B. Use the following choices to answer the next three questions:
a) 5' > 3' polymerase activity
b) 3' > 5' polymerase activity
c) 5' > 3' exonuclease activity
d) 3' > 5' exonuclease activity
e) 3' > 5' endonuclease activity
1. Is responsible for the synthesis of DNA. (
2. Is responsible for proofreading. (
)
)
3. Is responsible for removal of the primer during replication. (
)
Bonus Questions:
Q. What is the advantage of complex transcription units over simple transcription
units?
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Q. Describe the similarities and differences between prokaryotic and eukaryotic DNA
polymerases and Poly A polymease
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All the best , Dr. Raida W. Khalil