Number of questions: 30

PDF file Each question has only one answer.

1.  Women at high risk for Hereditary Nonpolyposis Colorectal Cancer (HNPCC) should not only undergo colon/rectum screening, but also screening of their: Answer

A.  Lungs.

B.  Uterus-endometrium.

C.  Kidneys.

D.  Heart.

E.  None of the above.

A.  A protein that is coded by an oncogene and is only expressed in cancer cells.

B.  A transmembrane glycoprotein expressed on normal epithelium and breast cancer cells.

C.  An oncoprotein over-expressed on normal epithelial cells of the breast.

D.  A transmembrane oncoprotein that is over-expressed in all breast cancer.

3.   In vitro denaturation of DNA is typically achieved by all of the following except: Answer

A.  Treatment by acids such as hydrochloric acid.

B.  High temperature.

C.  Organic solvents (hydrogen-bond solvents).

D. Treatment by alkaline such as sodium hydroxide.

A.  Cause initiation of transcription.

B.  Cause termination of transcription.

C.  Cause initiation of translation.

D.  Cause termination of translation.

E.  Are designated by UAG, UAA, and UGA in all genetic codes.

5.   During Southern blot hybridization analysis, the step following extraction of DNA is generally: Answer

A.  Electrophoresis in an agarose gel.

B.  Denature DNA with alkaline treatment.

C.  Hybridize with a gene-specific probe.

D.  Digest with specific restriction endonuclease(s).

E.  Apply DNA to a nylon membrane.

6.   Genes such as N-MYC and HER2 can be amplified in certain tumors. Gene amplification can be detected by: Answer

A.  Fluorescent in situ hybridization (FISH).

B.  Southern blot.

C.  Quantitative real-time polymerase chain reaction (PCR).

D.  Microarray.

E.  All of the above.

7.   An allele-specific oligonucleotide (ASO) probe is useful in the detection of: Answer

A.  Substitution of a single base, micro deletion or insertion.

B.  Several mutations in a given gene sequence.

C.  Large deletions.

D.  Translocations.

E.  All of the above.

8.   The single most common molecular defect found in the cystic fibrosis transductance receptor (CFTR) gene and accounting for the majority of cystic fibrosis in Caucasians is: Answer

A.  A 3-bp deletion.

B.  A translocation.

C.  An inversion.

D.  An insertion.

E.  G542X mutation.

9.   The following Southern blot analysis uses a single restriction enzyme and two probes. The two probe loci are separated by an invariant restriction enzyme cut site. One blot was probed with probe A and the other with probe B.

In this two-probe/one-restriction enzyme Southern blot, how many polymorphic restriction enzyme cutting sites are there in total? (Hint: Draw the schematic showing the probe and gene sequence.) Answer

A.  One.

B.  Two.

C.  Three.

D.  Four.

E.  None.

10.  Migration rate of a macromolecule through a gel matrix during electrophoresis depends on: Answer

A.  Net charge on the molecule.

B.  Primary structure of the molecule.

C.  Size of the molecule.

D.  Type of gel matrix.

E.  All of the above.

11.  Sanger’s method of DNA sequencing: Answer

A.  Requires piperidine cleavage.

B.  Incorporates dideoxynucleotides.

C.  Depends upon restriction recognition sites.

D.  Terminates reactions by overloading dATP.

E.  Relies on chemical degradation of the DNA.

12.  Stringency refers to: Answer

A.  Control of specificity of hybridization.

B.  Annealing of amplicons.

C.  CAP checklist.

D.  Ultraviolet detection of PCR products.

E.  A cruel laboratory director.

13.  For reverse dot blots, what is labeled for detection? Answer

A.  Allele-specific oligonucleotide (ASO) probes.

B.  Polymerase chain reaction (PCR) products.

C.  The enzyme.

D.  The nylon membrane.

E.  None of the above.

A.  Exons.

B.  Introns.

C.  Cistrons.

D.  Ailerons.

E.  Splicing sites.

15.  If someone has a normal and mutant allelic banding pattern, they are said to be: Answer

A.  Heterozygous.

B.  Compound homozygous.

C.  Homozygous.

D.  Normal.

E.  Wildtype

16.  Single strand conformational polymorphism (SSCP) analysis depends on: Answer

A.  Hybridization temperature.

B.  Secondary structure of amplicons.

C.  Application of direct current in multiple orientations during electrophoresis.

D.  Homodimer and/or heterodimer formation.

E.  All of the above.

17.  The diagram below shows the location of the Factor V Leiden mutation in a 220 bp polymerase chain reaction (PCR) amplicon. The fragments shown are those formed from digestion of a normal allele following restriction enzyme digestion: Answer

What is the pattern expected from a homozygous Leiden patient?

A.  67, 37, 116.

B.  104, 116.

C.  67, 153.

D.  220.

E.  None of the above.

18.  Digene’s Hybrid Capture II assay is used to determine the presence or absence of human papilloma virus in a Pap specimen. It uses: Answer

A.  Pan-specific HPV probes.

B.  A cocktail of RNA probes.

C.  DNA sequencing.

D.  PCR amplification.

E.  Detection of signal by electrophoresis.

19.  A reverse transcriptase-polymerase chain reaction (RT-PCR) assay involves all of the following except: Answer

A.  DNA isolation and purification.

B.  Isothermal incubation.

C.  Thermal cycling.

D.  Conversion of RNA into DNA as the first step.

E.  The use of Taq DNA polymerase.

20.  The ligase chain reaction (LCR) includes: Answer

A.  Ligation of random oligonucleotides.

B.  Digestion of amplified products.

C.  Ligation of adjacent primer pairs.

D.  Isothermal amplification conditions

21.  What is the key advantage of Taq DNA polymerase over conventional polymerases? Answer

A.  Faster reaction kinetics.

B.  Thermostability.

C.  Increased substrate specificity.

D.  Decreased magnesium requirements.

22.  Which anticoagulant is generally not acceptable for PCR analysis? Answer

A.  Ethylenediamine tetra-acetic acid (EDTA).

B.  Heparin.

C.  Acetate-citrate-dextrose (ACD).

D.  The one found in lavender top blood tubes.

23.  Gel electrophoresis of RNA generally involves the use of buffer/gel containing either alkali or formaldehyde/formamide. The function of these reagents in the gel is to: Answer

A.  Increase the speed of electrophoresis.

B.  Prevent fragmentation of RNA.

C.  Inhibit any contaminating ribonucleases.

D.  Polymerize the gel.

E.  Disrupt any secondary structure of the RNA.

24.  In a fluorescent in situ hybridization (FISH) analysis of an atypical teratoid/ rhabdoid tumor (AT/RT) using a probe for chromosome 22q (BRC gene at 22q11.2) and a control probe (FL1 gene on chromosome 11),  the majority of cells were seen to display two green dots for the FL1 gene and one red dot for the BRC gene. These findings indicate: Answer

A.  No deletion of the BRC gene.

B.  Homozygous deletion of the BRC gene.

C.  Heterozygous deletion of the BRC gene.

D.  Translocation between chromosomes 22 and 11.

E.  Single point mutation on one copy of the BRC gene.

25.  A fluorescent in situ hybridization (FISH) assay designed to detect t(15;17)(q22;q21.1), uses a red probe for the PML gene on chromosome 15 and a green colored probe for the RAR gene on chromosome 17.  The probes are of significant size such that when a t(15;17) translocation is present the pattern seen in the majority of cells is two fusions (from the reciprocal exchange between 15 and 17) and  one red and one green (for the normal non-translocated 15 and 17). The other pattern seen in t(15;17) cells but more rarely is 3 fusions. What are all the possible combination patterns for normal (non-translocated) cells? (R= red, G= green, F= fusion)? Answer

A.  2F .

B.  2R/2G .

C.  1R/1G/1F or 2F .

D.  2R/2G or 1R/1G/1F.

E.  2R/2G or 1R/1G/1F or 2F.

26.  Which of the following is not true about Robertsonian translocations? Answer

A.  They occur in about 3% of patients with Down syndrome.

B.  Involve the breakage of two chromosomes at or near the centromeres and fusion of their long arms.

C.  Involves breakage of at least two chromosomes and exchange of fragments.

D.  Takes place most often between acrocentric chromosomes (13, 14, 15, 21 and 22), especially between 13q and 14q.

E.  The loss of the short arms in this process is inconsequential since they contain only genes for ribosomal RNA for which there are multiple copies

27. The percentage of agarose in gel electrophoresis for products of a polymerase chain reaction (PCR) usually would not exceed what level? Answer

A.  20%.

B.  10%.

C.  2%.

D.  0.5%.

28.  Which of the following isotopes are most commonly used to produce radioactive DNA and RNA probes to be used in molecular diagnostic procedures: Answer

A.  I¹²⁵

B.  C¹⁴

C.  P³² and P³³

D.  S³⁵

29.  The concentration of which of the following ions plays a critical role in polymerase chain reaction (PCR): Answer

A.  Na⁺

B.  K⁺

C.  Al⁺⁺⁺

D.  Mg⁺⁺

E.  Li⁺

30. The PCR-restriction enzyme assay below is designed to detect two different polymorphisms (A and B) in the same PCR fragment. The negative (no-DNA) control is in lane 1, the wildtype (no polymorphisms) is in lane 2, the heterozygous control for polymorphism A is in lane 3 and the heterozygous control for polymorphism B is in lane 4. What is the genotype for the patient analyzed in lane 5? Answer

A.  Wildtype A / heterozygous B with a novel polymorphism that creates an additional restriction site.

B.  Wildtype A / wildtype B with a novel polymorphism that creates an additional restriction site.

C.  Homozygous A / homozygous B.

D.  Wildtype A / wildtype A.

E.  The restriction enzyme failed to cut properly.