MOLECULAR DIAGNOSTICS EXAM 1
QUESTIONS AND ANSWERS 2025 /
2026
Translation is terminated when a stop codon is presented at the; - ANSWER-A site
According to the wobble hypothesis a U in the 5' position of anticodon can pair with; -
ANSWER-A or G
Which enzyme is incorrectly matched to it's function?
-RNA polymerase; transcription
-Aminoacyl-tRNA synthesis; attaches an amino acid to a tRNA
-PolyA polymerase; translation
-Guanlyl transferase- mRNA capping - ANSWER-Poly A polymerase- translation
During chromatin remodeling, which of the following is acylated to loosen it's contact
with the DNA? - ANSWER-histone Proteins
The most frequently methylated base in vertebrates is; - ANSWER-Cytosine
MicroRNAs, short endogenous RNA, perform what function in the eukaryotic cell? -
ANSWER-Repressing Gene Expression
Which of the following accurately descibes no invasive sources of DNA biomarkers?
-Urine is non invasive course of DNA biomarkers
-Blood samples can be collected with minimal discomfort to the patient and is
considered non infasive
-Spinal fluid is a non invasive source of DNA biomarkers
-All of the above
-Urine and Blood but not Spinal fluid - ANSWER-Urine and Blood but not Spinal fluid
Which whole blood fraction is the most abundant source of genomic DNA? -
ANSWER-Buffy Coat
Which of the following is the first step in DNA isolation from cells in clinical sample? -
ANSWER-Lysis of Cells
What is the concentration of DNA whereby a 1:100 dilution has an absorbance
reading of 0.015 at 260 nm? - ANSWER-75 ug/mL
PolyT oligomers bound to a matrix resin column will selectively isolate what? -
ANSWER-Messenger RNA
What is the concentration RNA whereby a 1:10 dilution has an absorbance reading
of 0.675 at 260 nm? - ANSWER-27 ug/mL
, The 260 nm ratio for DNA was determined to be 0.5. What should be done with next
sample? - ANSWER-Reprecipitate the DNA to remove excess protein
Nucleic Acids migrate toward which pole in electrophoresis? - ANSWER-Anode (+)
What is the advantage of agarose of polyacrylamide gels? - ANSWER-Agarose is
more stable
What is ethidium bromide? - ANSWER-an "intercalating agent"
a flourescent dye that binds DNA
Detects 0.1 ug DNA
As compared with traditional slab gel electrophoresis which of the following is not an
advantage of capillary electrophoresis? - ANSWER-Cost of instrumentation labels
Purines - ANSWER-Adenine and Guanine (2 rings)
Pyramidines - ANSWER-cytosine, thymine, uracil
How are nucleotides joined together? - ANSWER-Ribose and phosphate groups
DNA polarity - ANSWER-5'-phosphate / 3'-hydroxyl
How is a new DNA strand polymerized? - ANSWER-5-3'
Parent strand is read 3-5'
How are DNA strands connected? - ANSWER-hydrogen bonds between bases
A-T
C-G
DNA replication starts during what phase - ANSWER-S phase of interphase, before
cell division
Semiconservative DNA replication - ANSWER-New DNA is one parent strand and
one new
DNA replication start location - ANSWER-Origin
Makes a replication fork
Primase (RNA pol) function - ANSWER-synthesizing an RNA primer, required for
DNA replication
DNA helicase function - ANSWER-An enzyme that unwinds the DNA strand for
replication, breaks hydrogen bonds
DNA polymerase function - ANSWER-adds new nucleotides to the strands,
proofreads and fixes errors
Catalyze formation of phosphodiesterase bonds
QUESTIONS AND ANSWERS 2025 /
2026
Translation is terminated when a stop codon is presented at the; - ANSWER-A site
According to the wobble hypothesis a U in the 5' position of anticodon can pair with; -
ANSWER-A or G
Which enzyme is incorrectly matched to it's function?
-RNA polymerase; transcription
-Aminoacyl-tRNA synthesis; attaches an amino acid to a tRNA
-PolyA polymerase; translation
-Guanlyl transferase- mRNA capping - ANSWER-Poly A polymerase- translation
During chromatin remodeling, which of the following is acylated to loosen it's contact
with the DNA? - ANSWER-histone Proteins
The most frequently methylated base in vertebrates is; - ANSWER-Cytosine
MicroRNAs, short endogenous RNA, perform what function in the eukaryotic cell? -
ANSWER-Repressing Gene Expression
Which of the following accurately descibes no invasive sources of DNA biomarkers?
-Urine is non invasive course of DNA biomarkers
-Blood samples can be collected with minimal discomfort to the patient and is
considered non infasive
-Spinal fluid is a non invasive source of DNA biomarkers
-All of the above
-Urine and Blood but not Spinal fluid - ANSWER-Urine and Blood but not Spinal fluid
Which whole blood fraction is the most abundant source of genomic DNA? -
ANSWER-Buffy Coat
Which of the following is the first step in DNA isolation from cells in clinical sample? -
ANSWER-Lysis of Cells
What is the concentration of DNA whereby a 1:100 dilution has an absorbance
reading of 0.015 at 260 nm? - ANSWER-75 ug/mL
PolyT oligomers bound to a matrix resin column will selectively isolate what? -
ANSWER-Messenger RNA
What is the concentration RNA whereby a 1:10 dilution has an absorbance reading
of 0.675 at 260 nm? - ANSWER-27 ug/mL
, The 260 nm ratio for DNA was determined to be 0.5. What should be done with next
sample? - ANSWER-Reprecipitate the DNA to remove excess protein
Nucleic Acids migrate toward which pole in electrophoresis? - ANSWER-Anode (+)
What is the advantage of agarose of polyacrylamide gels? - ANSWER-Agarose is
more stable
What is ethidium bromide? - ANSWER-an "intercalating agent"
a flourescent dye that binds DNA
Detects 0.1 ug DNA
As compared with traditional slab gel electrophoresis which of the following is not an
advantage of capillary electrophoresis? - ANSWER-Cost of instrumentation labels
Purines - ANSWER-Adenine and Guanine (2 rings)
Pyramidines - ANSWER-cytosine, thymine, uracil
How are nucleotides joined together? - ANSWER-Ribose and phosphate groups
DNA polarity - ANSWER-5'-phosphate / 3'-hydroxyl
How is a new DNA strand polymerized? - ANSWER-5-3'
Parent strand is read 3-5'
How are DNA strands connected? - ANSWER-hydrogen bonds between bases
A-T
C-G
DNA replication starts during what phase - ANSWER-S phase of interphase, before
cell division
Semiconservative DNA replication - ANSWER-New DNA is one parent strand and
one new
DNA replication start location - ANSWER-Origin
Makes a replication fork
Primase (RNA pol) function - ANSWER-synthesizing an RNA primer, required for
DNA replication
DNA helicase function - ANSWER-An enzyme that unwinds the DNA strand for
replication, breaks hydrogen bonds
DNA polymerase function - ANSWER-adds new nucleotides to the strands,
proofreads and fixes errors
Catalyze formation of phosphodiesterase bonds
