ISLAMIC UNIVERSITY
SCHOOL OF SCIENCE
Medical Genetics
Final Exam
June, 2007
Student Name: ---------------------------1. A student discovers that a certain disease is associated with an abnormality
in chromosome 21. He is using what type of genetics to make this discovery?
a.
b.
c.
d.
Mendelian genetics
Population genetics
Molecular genetics
Cytogenetics
2. Alternative forms of the same locus
a. Allele
b. Chromosomal location
c. Mutation
d. Polymorphism
3. A trait that regularly expressed in heterozygotes
a. Recessive
b. Dominant
c. Codominant
d. Incomplete dominant
4. Which of the following is NOT true
a. All diseases phenotypes result from the interaction between genes and the
environment
b. Some phenotypes are primarily genetically determined
c. Many phenotypes require genetic and environmental factors
d. Some phenotypes result primarily from the environment
5. Type-II diabetes is considered as a
a. Single gene disorder
b. Chromosomal disorder
c. Polygenic disease
d. None of the above
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6. The most probable mode of inheritance of the disease illustrated in the
pedigree below is:
a. Autosomal dominant
b. X-linked dominant
c. Mitochondrial
d. Both "a" and "b"
7. A segment of DNA has one strand with the following sequence of bases.
5'-AGC GCA TAG CAA-3'. The mRNA sequence coded for by this strand is:
a. 5'-UCG CGU AUC GUU-3'
b. 5'-TCG CGT ATC GTT-3'
c. 5'-TTG CTA TGC GCT-3'
d. 5'-UUG CUA UGC GCU-3
8. 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
9. DNA replication occurs
a. In a few hours
b. Slowly
c. Before a cell divides
4. After completion of cell division
10. Which of the following statements is NOT correct
a. DNA synthesis during S phase is not synchronous on all chromosomes
b. Individual chromosome segments have their own characteristic time
of replication during S phase
c. less condensed chromatin, usually containing genes, replicates late
d. DNA synthesis begins at 100s - 1000s of sites called Origins of
DNA Replication
11. DNA damage checkpoints sense DNA damage
a. before the cell enters S phase (a G1 checkpoint);
b. during S phase
c. after DNA replication (a G2 checkpoint).
d. All of the above
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12. Which of the following is true about P53?
a. Encode a protein that binds to each kinetochore until a spindle fiber
attaches to it
b. Gets its name from a human disease of that name
c. Senses DNA damage and can halt progression of the cell cycle in G1
d. protein is not involved in apoptosis
13. Chromosomes are becoming visible, the nucleolus and nuclear membrane are
disappearing
a. Telophase
b. Metaphase.
c. Prophase
d. Prometaphase
14. Which of the following is NOT correct regarding cancer?
a. It is a set of diseases where cells escape the cell cycle controls
b. It is always due to mutations in proto-oncogenes
c. Usually multiple mutations must occur
d. May be caused by spontaneous mutations, viral infections, and mutagens
15. The correct nomenclature of a female with a reciprocal translocation
involving parts of the short arms of chromosomes 8 and 11 is:
a. 46, XX, -8,-11,+ t(8;11)(q34;q11)
b. 46, XX, -8,-11,+ t(8;11)(p34;p11)
c. 45, XX, -8,-11,+ t(8;11)(p34;p11)
d. 47, XX, + t(8;11)(p34;p11)
16. Each spermatid
a. Contains 46 chromatids
b. Contains 23 chromatids
c. Contains 23 duplicated chromosomes
d. Contains 46 chromosomes
17. Chromosomes reach maximal condensation
a. Diploteen
b. Pachytene
c. Diakinesis
d. Zygotene
18. The structure shown in the diagram below is
a. 5-methyl cytosine
b. 5-methyl thymine
c. Thymine
d. Cytosine
19. Unwinds DNA
a. Primase
b. Helicase
C. Ligase
D. Telomerase
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20. Replicates mitochondrial DNA
a. Polymerase gamma
b. Polymerase alpha
c. Polymerase delta
d. Polymerase beta
21. In eukaryotes, the RNA polymerase that makes mRNA is:
a. Polymerase I
b. Polymerase II
c. Polymerase III
d. Eucaryotes only have one RNA polymerase
22. A cap is:
a. A short stretch of G’s added to the 5’ end of DNA
b. A special amino acid added to the amino end of a protein
c. A methylated guanosine nucleotide added to the 5’ end of mRNA
d. A recognition signal used in splicing
23. You have identified a region of DNA that stimulates transcription.
However, it is not affected by orientation, and can be moved a hundred base
pairs from the promoter and still works. This is characteristic of:
a. Origins of replication
b. Enhancers
c. Promoters
d. Silencers
24. When an organism gains or loses one or more chromosomes but not a
complete haploid set, the conditions is known as
a. Polyploidy
b. Euploidy
c. Aneuploidy
d. Trisomy
25. During translation, chain elongation continues until:
a. No amino acids are left
b. All tRNAs are empty
c. The polypeptide is long enough
d. Stop codon is reached
26. Which structure is coded for by the shortest (or smallest) sequence of
DNA?
a. A tRNA having 75 nucleotides
b. A mRNA having 75 codons
c. A polypeptide composed of 75 amino acids
d. A protein composed of 2 polypeptides, each 35 amino acids long
27. Necessary for completion of linear DNA ends
a. DNA polymerase gamma
b. Ligase
c. Telomerase
d. Primase
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28. A geneticist found that a particular mutation had no effect on the amino
acid sequence of the polypeptide encoded by a gene. This mutation probably
involved
a. Deletion of the entire gene
b. Insertion of one nucleotide
c. Substitution of one nucleotide
d. Deletion of one nucleotide
29. 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. Are always transitions
d. Result when one nucleotide is changed for another
30. Which one of the following situations is an example of germline
mosaicism?
a. A mother, who is clinically normal, has two children by different healthy
mates, and both of the children have a lethal autosomal dominant disorder.
b. A woman heterozygous for hemophilia A
c. A man heterozygous for a mutation causing cystic fibrosis
d. A man with colorectal cancer
31. In DNA hybridization:
a. DNA is broken down into a mixture of nucleotides
b. Is heated to become single-stranded and finds a complementary strand to
again become double-stranded
c. Single-stranded DNA replaces portions of double-stranded DNA in the cell
d. The DNA is heated and as it cools becomes partially chemically converted
to a mixture of RNA and DNA
32. A man first develops symptoms of and is diagnosed with Huntington
disease at age 50, while his daughter develops depression and abnormal
movements at age 30
a. Anticipation
b. Pleiotropy
c. Incomplete penetrance
d. Variable expressivity
33. A man with a mitochondrial myopathy has a mutation detectable in 25% of
his mitochondrial DNA
a. Heteroplasmy
b. Incomplete penetrance
c. Variable expressivity
d. Dominant negative effect
34. Mutations in the gene FBN1 cause Marfan syndrome. A patient with a
mutation that completely deletes one allele has a much milder phenotype than
a patient with a missense mutation
a. Locus heterogeneity
b. Incomplete penetrance
c. Autosomal recessive
d. Dominant negative effect
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35. Alu and L1 insertions
a. Are common disease-producing mutations
b. Are “cut-and-paste” insertions of mobile DNA
c. Require reverse transcription of an RNA intermediate
d. Are not found in human
36. Two cousins with ectrodactyly, an autosomal dominant malformation,
have unaffected parents
a. Uniparental disomy
b. New mutation
c. Incomplete penetrance
d. Variable expressivity
37. For the alleles of the ABO blood group system, if the allele frequencies in
a large study found: f(A): 0.3,
f(B): 0.2,
f(O): 0.5. The frequency of
genotype AB is:
a. 0.06
b. 0.12
c. 0.09
d. 0.04
38. You are consulted by a couple, Muna and Ali, who tell you that Muna’s
sister Samah has Hurler syndrome (a mucopolysaccharidosis) and that they
are concerned that they might have a child with the same disorder. Hurler
syndrome is an autosomal recessive condition with a population incidence of
1 in 9,00 in their community. If Muna and Ali are not consanguineous, what is
the approximate probability that their first child will have Hurler syndrome?
a. 25%
b. 1%
c. 10%
d. 0.75%
39. With regard to the pedigree shown below, all of the following explanations
about the disease are possible, EXCEPT
a. Autosomal recessive disorder
b. X-linked recessive disorder
c. Autosomal dominant due to new mutation
d. Autosomal dominant with a germline mosaic parent
e. X-linked dominant with complete penetrance
40. X chromosome inactivation depends on
a. Promoter methylation of certain genes
b. Non-coding RNA painting the inactive X
c. Histone acetylation
d. Both a and b
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41. The bands below the following figure refer to:
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2
3
4
a. PCR-amplified fragments from a locus having VNTR polymorphism
b. ASO that hybridizes to normal or mutant alleles at a given locus
c. SSCPs that reveal variation at a locus
d. Northern blot test results
42. Nitrous acid leads to
a. Frameshifts
b. CG  TA transitions
c. GC  AC transitions
d. GT  AT transitions
43. The most likely pattern of inheritance in the following pedigree is
a. Autosomal dominant
b. X-linked dominant
c. X-linked recessive
d. Autosomal recessive
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44. Detected by a fluorescence microscope
a. Q-banding
b. G-banding
c. R-banding
d. C-banding
45. While studying a DNA fragment sequence you found 20 A's, 25 G's, 30
C's, and 22 T's. How many of each base is found in the complete doublestranded molecule?
a. A=40, G=50, C=60, T=44
b. A=44, G=60, C=50, T=40
c. A=45, G=45, C=52, T=52
d. A=42, G=55, C=55, T=42
46. A couple with normal vision from an isolated community have a child with
autosomal recessive ornithine aminotransferase deficiency resulting in gyrate
atrophy of retina. The child grows up, marries a member of the same
community who has normal vision and has a child with the same enzyme
deficiency. Which of the followings best explains this situation?
a. New mutation
b. Uniparental disomy
c. High carrier frequency
d. New mutation
47. Which of the following persons is expected to be phenotypically normal?
a. A female with the karyotype 47,XX,+13
b. A male with a deletion in the short arm of chromosome 4
c. A person with a deletion in the short arm of chromosome 5
d. A person with a small deletion in the short arm of chromosome 15
48. The 30 nm fiber is
a. The nucleosome fiber
b. The solenoid
c. The DNA double helix
d. The metaphase chromosome
49. The number of possible heterozygous genotypes for a 5-allele locus is:
a. 15
b. 10
c. 12
d. 8
50. A phenotype that is autosomally transmitted but expressed in only one sex
is called
a. X-linked recessive
b. Sex-influenced
c. Sex-limited
d. Mosaicism
51. The most appropriate method for detection of microdeletions is:
a. G-banding
b. FISH
c. Sequencing
d. Western blot
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52. BRCA1 and 2 genes are involved in
a. Base excision repair
b. Nucleotide excision repair
c. Detection of mismatches
d. Double-strand breaks repair
53. DNA fingerprinting is usually determined through the use of
a. Short tandem repeat polymorphism
b. ABO blood types polymorphism
c. Alu sequences
d. Spectral karyotyping
54. Prader-willi syndrome is usually due to
a. Having the 15q11-q13 genetic information only from father
b. Autosomal dominant mutation on chromosome 15
c. Trisomy 15
d. Having the 15q11-q13 genetic information only from mother
55. One of the following mutagens causes frameshift mutation
a. Base analogues
b. Intercalating agents
c. Deamination of 5-methyl cytosine
d. Alkylating agents
56. This factor disturbs Hardy-Weinberg equilibrium
a. Random mating
b. Large population
c. Consanguineous marriage
c. Absence of new mutations
57. In one study, 5 achondroplastic children were born in a series of 250,000
consecutive births (Achondroplasia is autosomal dominant and fully
penetrant). Assuming that all those cases are due to new mutation, the
mutation frequency for this locus is:
a. 0.025
b. 0.05
c. 1x 10-5
d. 1x10-4
58. A DNA cloning vector that can carry fragments of up to 1000 kb
a. Bacterial artificial chromosome
b. Bacteriophage lambda
c. Cosmid
d. Yeast artificial chromosome
59. Introns and flanking regulatory sequences are absent
a. Microarray
b. cDNA library
c. Mitochondrial DNA library
d. Genomic DNA libraries from different developmental stages
60. Labeled probes are used in all of the followings EXCEPT
a. Southern Blot
b. ASO hybridization
c. Detection of proteins in specific tissue sections
d. Fluorescence in situ hybridization
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