Msc program exam questions for medical laboratory scientists

1. The Academy of Medical Sciences & Technology
Faculty of Medical Laboratory Sciences
M.Sc Programme in Medical Laboratory Sciences
Batch (1) Final Semester (1) examinations
Molecular Biology
Date: Monday 22.1.2007 Time allowed: 3 hours
3:00 – 6:00 p.m.
Name………………………………………………………………………………………
Index Number……………………………………
Answer all questions
SECTION ONE: One Best Answer:
Each of the following statements is followed by five suggested answers or
completions. Draw a circle around the letter of the best answer.
1. Each gene minimally dictates the production of one:-
a. chromosome
b. codon
c. tRNA
d. DNA strand
e. polypeptide
2. The information carried by a DNA molecule is in:-
a. the sugars and phosphates forming its backbone
b. the total number of nucleotides it contains
c. the order of the nucleotides in the molecule
d. its amino acid sequence
e. the RNA units that make up the molecule
3. Which are arranged in the correct order by size, from largest to smallest?
a. chromosome - gene - nucleotide – codon
b. chromosome - gene - codon – nucleotide
c. codon - chromosome - gene - nucleotide
d. nucleotide - chromosome - gene – codon
e. gene - chromosome - codon – nucleotide
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2. 4. The bases on one strand of DNA are CTAGAAC. The complementary section on
the other strand of DNA is:-
a. CTAGAAC
b. AGCTCCA
c. GATCTTG
d. TCGAGGT
e. GUTCTTG
5. Rejoining DNA fragments from two organisms is best known as:-
a. Conjugating DNA
b. Declining DNA
c. mapping genes
d. recombinant DNA technology
e. gene sequencing
6. The gene-cutting tools of recombinant DNA technology are:-
a. helicases
b. DNA ligases
c. DNA vectors
d. Plasmids
e. Restriction enzymes
7. Chain termination DNA sequencing:-
a. Requires a DNA polymerase
b. Uses trideoxynucleotides
c. Requires two primers
d. Uses double-stranded DNA
e. uses piperidine to cleave modified bases
8. Introns:-
a. Are always flanked by exons
b. Occur only in genes
c. Do not contain any meaningful sequence
d. Often contain translation stop codons
e. C is the only wrong answer
9. Point mutations:
a. remain in the parent and cannot be passed on to the offspring
b. occur at the 5' end of a DNA strand
c. forces the genetic code to be read from the wrong point
d. are caused by a break in the chromosome
e. result when one nucleotide is changed for another
10. Electrophoresis is used to:-
a. amplify small DNA samples to obtain enough for analysis
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3. b. clone genes
c. match a gene with its function
d. cut DNA into fragments
e. separate fragments of DNA
11. DNA fingerprints used as evidence in a murder trial look something like
supermarket bar codes. The pattern of bars in a DNA fingerprint shows:-
a. the order of genes along particular chromosomes
b. the presence of various-sized fragments of DNA
c. the exact location of a specific gene in a genomic library
d. the presence of dominant or recessive alleles for particular traits
e. the order of bases in a particular gene
12. The immediate goal of the Human Genome Project was to:-
a. Develop new technologies for studying DNA.
b. compare the genomes of a large number of individuals from different parts of
the world
c. map and sequence the genomes of important research organisms such as
Drosophila sp
d. map all the human genes and determine the nucleotide sequence of the entire
human genome
e. find cures for human genetic disorders
13. Imagine an error occurring during DNA replication in a cell, so that where there
is supposed to be a T in one of the genes there is instead a G. What effect will
this
probably have on the cell?
a. The amino acid sequence of one of its kinds of protein will be completely
changed
b. Each of its kinds of protein will contain an incorrect amino acid
c. One of its kinds of protein might contain an incorrect amino acid
d. An amino acid will be missing from one of its kinds of protein
e. An amino acid will be missing from each of its kinds of protein
14. A fast-growing new field of science that seeks to predict the structure of a
protein from its nucleotide sequence is called:-
a. genomics
b. proteomics
c. bioinformatics
d. nucleonics
e. non of the above.
15. Who first developed the DNA sequencing approach using dideoxynucleoside
triphosphates in DNA synthesis?
a. Pauling
b. Watson and Crick
c. Maxam and Gilbert
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4. d. Sanger
e. Morgan
16. The field that is concerned with the management and analysis of biological data
using computers is:-
a. biostatistics
b. genomics
c. bioinformatics
d. population genetics
e. non of the above
17. RFLP analysis is a technique that:-
a. uses hybridization to detect specific DNA restriction fragments in genomic
DNA
b. is used to determine whether a gene is transcribed in specific cells
c. measures the transfer frequency of genes during conjugation
d. is used to detect genetic variation at the protein level.
e. is used to amplify genes for producing useful products
18. Simple tandem repeat polymorphisms in humans are most useful for:-
a. solving criminal and paternity cases
b. reconstructing the relationships of humans and chimps.
c. estimating relationships of humans and Neanderthals
d. transferring disease resistance factors into bone marrow cells
e. estimating matches for blood transfusions
19. The polymerase chain reaction (PCR):-
a. uses flanking primers
b. uses restriction enzymes
c. uses varying temperatures
d. all of the above
e. a and c
20. PCR is used for:-
a. reverse transcribing RNA into DNA
b. digesting proteins
c. digesting DNA
d. copying plasmids
e. amplifying DNA
21. Transformation:-
a. converts DNA into RNA
b. converts RNA into proteins
c. joins two DNA fragments
d. cuts DNA into fragments
e. is used in cloning of DNA
22. Each nucleotide in a DNAmolecule is composed of:-
a. a nitrogenous base and a phosphate group
b. a sugar called ribose, a nitrogenous base, and a phosphate group
c. a sugar called deoxyribose, a nitrogenous base, and a phosphate group
d. a sugar called deoxyribose and a phosphate group
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5. e. deoxyribose and a nitrogen base.
23. Which vector would be most appropriate for cloning a 150 kb fragment of
DNA:-
a. a plasmid
b. a lambda vector
c. a BAC
d. a YAC
e. cosmid
24. Regarding EcoRI:-
a. It is originally derived from a bacterium
b. The first letter in its name refers to the genus of the bacterium
c. The letter R refers to the strain of the bacterium
d. The numerical I indicates the order of discovery
e. All a, b, c and d are correct
25. All fragments cut by most restriction endonucleases have:-
a. complementary double-stranded ends
b. supplementary single-stranded ends
c. double-stranded "sticky" ends
d. complementary single-stranded ends
e. double-stranded supplementary ends
26. Bacterial DNA is not cleaved by their own restriction enzymes because bacteria
add _______________ to their own DNA:-
a. nucleotides
b. peptides
c. methyl groups
d. resistant genes
e. phosphate groups
27. Which of the following is palindrome sequence:-
a. 5`- CTGCAG-3`
b. 5`- CTAGAC –3`
c. 5` - GCCTGC-3`
d. 5`-CCACGG-3`
e. 5`- CAGCAG-3`
28.Which of the following tools of recombinant DNA technology is INCORRECTLY
paired with its use?
a. restriction endonucleases production of DNA fragments for gene cloning
b. DNA ligase - enzyme that cuts DNA, creating sticky ends.
c. DNA polymerase - copies DNA sequences in the polymerase chain reaction
d. reverse transcriptase - production of cDNA from mRNA
e. electrophoresis – analysis of PCR products
29. Gene library" is a term used to describe:-
a .a computerized listing of known DNA sequences
b. bacteria with plasmids containing DNA fragments representing the majority of
the genetic information from a plant or animal.
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6. c. a collection of books about recombinant DNA technology.
d. a compilation of the amino acid sequences of protein coding genes
e. none of the above
30. Recognition sites of restriction enzymes:-
a. are on double stranded DNA
b. can be 4-8 bp long
c. provide blunt and sticky ends
d. are usually palindrome sequences
e. all of the above (a-d) is correct.
31. For a genetic disease, point mutations are usually first found by:-
a. DNA hybridization
b. DNA sequencing
c. DNA cloning
d. Southern Blot
e. PCR
32. Cutting genomic DNA with a single restriction enzyme will result in DNA
fragments that:-
a. are all of the same length
b. all end with the same base sequence pattern
c. all migrate the same distance on a gel
d. all have the same molecular weight
e. all contain the same genes
33. A northern blot is used to separate and study:-
a. genomic DNA
b. cDNA
c. RNA
d. short polypeptides
e. proteins
34. In DNA hybridization the oligonucleotide complementary to target sequence is
called:-
a. vector
b. antibody
c. plasmid
d. probe
e. primer
35. Which of the following statements is true about developing cDNA?
a. mature mRNA directs the formation of the DNA.
b. mature mRNA does not contain introns
c. DNA taken from the nucleus is used to produce the cDNA
d. Both a and b are true.
e. none of the above are true
36. The following statements are true regarding Southern blotting EXCEPT:-
a. It is the transfer of DNA from a gel onto nylon membrane
b. It involves transfer of double stranded DNA from a gel to nylon membrane
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7. c. It is helpful in detection of certain strains of infectious agents
d. It is used for detection of a mutation in a given gene
e. It uses capillary diffusion for fragment transfer
37. A cDNA library differs from a genomic library:-
a. in excluding DNA that codes for mitochondrial proteins.
b. In excluding DNA that codes ribosomal proteins.
c. Only by having longer polynucleotide fragments.
d. Only by having exons excised from gene.
e. In having only sequences that are expressed as mRNA
38. Restriction endonucleases:-
a. Digest DNA duplex molecules from 5` end.
b. Attack only single stranded DNA.
c. Have base sequence specificity
d. Randomly digest double stranded DNA molecules.
e. Are produced in eukaryotes.
39. The following techniques are used to immobilize the corresponding
biomolecules:-
a. Southern blotting for DNA
b. Northern blotting for proteins
c. Southern blotting for DNA and RNA
d. Dot-blot for RNA
e. Western blotting for DNA
40. Nonionizing radiations:-
a. Causes promotion of electrons to higher energy level within DNA.
b. Is exemplified by UV light.
c. Causes DNA to loose electrons
d. Can lead to formation of pyrimidine dimmers from adjacent pyrimidine bases.
e. a, b c and d are correct
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8. SECTION TWO
Answer all questions in the answer book provided.
Question One
Mutations are permanent, heritable alterations in the base sequence of the DNA.
Mutations could generally arise from DNA damage by environmental mutagens or
from mistakes that occur when a cell copies its DNA in preparation for cell division.
A. Define the following terms giving examples wherever possible:
(i). Transition
(ii). Transversion
(iii). Silent mutation
(iv) Acceptable missense mutation
(v). Nonsense mutation
B. Give examples for two physical and two chemical mutagens indicating their effect.
C. Briefly discuss the following DNA repair mechanisms:
(i). Photoreactivation
(ii). Base excision repair
(iii). Mismatch repair
Question Two:
A. What are the characteristic features of each of the following cloning vectors?
(i) Plasmids (ii) Cosmids (iii) YACs.
B. With aid of diagrams outline the general procedure of gene cloning.
C. What are dideoxyribonucleotides? Indicate their role in the Sanger method of DNA
sequencing?
D. With the sequence 5’-GCTGATTCGAGGTCAAAC-3’ and the primer 5’-
GTTTGAC- 3’ give all of the possible sequencing products with the reaction that
includes ddATP, dGTP, dTTP, and dCTP AND dATP.
Question Three.
The mechanisms involved in gene expression are not fully understood in details in
prokaryotes and eukaryotes. However, the lac and trp operons show good examples
of how the expression of some genes is controlled.
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9. A. List the components of the lac operon sequentially (starting from the 5` end).
B Explain why adding lactose induces lac operon but adding tryptophan represses the trp
operon.
C. What is the catabolite activator protein (CAP) and how does it affect gene expression
at the lac operon?
D. Briefly outlines how transcriptional attenuation is used to control expression of genes
involved in tryptophan biosynthesis in E. coli.
Good Luck!
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10. A. List the components of the lac operon sequentially (starting from the 5` end).
B Explain why adding lactose induces lac operon but adding tryptophan represses the trp
operon.
C. What is the catabolite activator protein (CAP) and how does it affect gene expression
at the lac operon?
D. Briefly outlines how transcriptional attenuation is used to control expression of genes
involved in tryptophan biosynthesis in E. coli.
Good Luck!
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