ASCP Molecular Biology Certification Exam Questions and answers 2024

ASCP
Molecular
Biology
Certification
Exam
Questions
and
answers
2024
Pyrimidine
-
ANSWER-One
carbon
ring
Cytosine,
Thymine,
Uracil
Purine
-
ANSWER-Two
carbon
rings
Adenine,
Guanine
How
are
nucleotides
joined
together?
-
ANSWER-Condensation
to
form
phosphodiester
bond
What
is
the
function
of
mRNA?
-
ANSWER-Carries
genetic
info
out
of
nucleus
Transcript
translated
to
protein
What
is
the
function
of
tRNA?
-
ANSWER-Carries
aa
to
ribosome
Anticodon
pairs
with
codon
on
mRNA
strand
What
is
the
function
of
rRNA?
-
ANSWER-part
of
ribosome
structure
most
abundant
RNA
coordinated
coupling
of
tRNA
to
mRNA
codons
Feedback
inhibition
-
ANSWER-Product
of
pathway
is
noncompetitive
inhibitor
Binds
to
allosteric
site
to
slow
down
rxn
b/c
too
much
product
Exonucleases
-
ANSWER-Degrades
nucleic
acids
by
removing
one
terminal
nt
at
a
time
Cleaves
phosphodiester
bond
at
end
of
chain
5'
-->
3'
and
3'
-->
5'
Endonucleases
(Prok)
-
ANSWER-Restriction
enzymes
Cleaves
phoshpodiester
bonds
w/i
poly-nt
chain
Recognition
site
is
palindromic
sequence
Types
I-V
ORI
sites
-
ANSWER-nt
sequence
where
replication
is
initiated
Topoisomerase
I
-
ANSWER-Induces
ss
breaks
Remove
DNA
supercoils
during
TXN
and
DNA
replication;
for
strand
breakage
during
recombination;
for
chr
condensation;
and
to
disentangle
intertwined
DNA
during
mitosis topoisomerase
II
-
ANSWER-cuts
both
strands
of
one
DNA
double
helix,
passes
another
unbroken
DNA
helix
through
it,
and
then
reanneals
the
cut
strands
Gyrase
(topoisomerase
II)
-
ANSWER-Unwinds
supercoiling
caused
by
unwinding
at
the
rep
fork
by
introducing
DSBs
Helicase
-
ANSWER-Breaks
H-bonds
of
double
helix
at
the
replication
fork
Primase
-
ANSWER-DNApol
α
(DNA
dep
RNA
pol)
adds
short
segments
of
complementary
RNA
to
ssDNA
template
(primers),
serves
as
starting
points
for
replication
single-strand
DNA
binding
proteins
(SSBPs)
-
ANSWER-Binds
ssDNA
and
prevents
it
from
re-annealing
during
TXN,
replication,
repair,
and
recombination
Okazaki
fragments
-
ANSWER-Short
fragments
of
DNA
synthesized
by
DNApol
δ
using
the
lagging
strand
(3'->5')
as
a
template
Ligase
-
ANSWER-Closes
gaps
in
DNA
Catalyzes
phosphodiester
bond
between
3'OH
and
5'P
What
are
the
steps
in
DNA
replication?
-
ANSWER-1.
Initiate
2.
Elongate
3.
Terminate
Telomeres
-
ANSWER-Repeat
sequence
(TTAGGG)
at
the
ends
of
chr,
protect
chr
from
degradation
RNA
polymerase
-
ANSWER-DNA
dependent
RNApol
Transcribes
DNA
template
to
RNA
(3'-->5';
anti-parallel)
Splicesomes
-
ANSWER-Complex
of
snRNPs
Removes
introns
from
pre-mRNA
and
splices
exons
together
Enhancers
-
ANSWER-Short
regions
of
DNA
that
bind
proteins
(TXN
factors)
that
enhance
TXN
of
a
gene
Poly-A
tail
-
ANSWER-Prevents
mRNA
from
being
degraded
in
cytoplasm
100-250
A's
at
3'
end
5'
cap
-
ANSWER-5'-5'
pyrophosphate
bridge
to
a
methylated
G
added
to
5'
end
of
a
mRNA
Protects
against
degradation
and
as
a
recognition
signal
for
TLN
apparatus aminoacyl
tRNA
-
ANSWER-tRNAs
that
carry
amino
acids
Ribosomes
-
ANSWER-Where
TLN
occurs
Prok:
30s
and
50s
Euk:
40s
and
60s
Catalyzes
peptide
bond
between
a.a.'s
What
is
the
path
of
a
tRNA
in
a
ribosome?
-
ANSWER-Acceptor
>
Peptidyl
>
Exit
How
is
translation
initiated?
-
ANSWER-small
rRNA
(40S)
subunit
binds
mRNA
and
scans
for
start
codon
(AUG)
Met-tRNA
is
brought
to
the
P
site
Large
rRNA
(60S)
subunit
binds
How
is
translation
terminated?
-
ANSWER-Occurs
when
stop
codon
enters
A
site
Release
factor
recognizes
stop
codon,
hydrolyzes
ester
bond
with
P
site,
releasing
aa
chain
Reverse
transcriptase
-
ANSWER-enzyme
that
transcribes
RNA
to
cDNA
(lacks
introns)
RNA
-->
RNA:DNA
-->
cDNA
(dsDNA)
Pleiotrophy
-
ANSWER-a
single
gene
controls
the
expression
of
many
phenotypic
traits
ie
Sickle
Cell
Anemia
cDNA
-
ANSWER-intron
free
complementary
DNA
can
be
inserted
into
a
plasmid
Vector
-
ANSWER-helps
carry
DNA
into
cell
ie
plasmids,
virus
Open
Reading
Frame
(ORF)
-
ANSWER-sections
of
DNA
that
begin
with
start
codons
and
end
with
stop
codons
DNA:
5'
-->
3'
transcription:
3'
-->
5'
DNA
-->
RNA
(promoter)
translation:
5'
-->
3'
mRNA
Spectrophotometer
-
ANSWER-Measures
amount
of
light
absorbed
Quantitative
measurement
of
[DNA/RNA]
At
what
wavelength
does
DNA
and
RNA
absorb?
-
ANSWER-260
nm
At
what
wavelength
does
protein
absorb?
-
ANSWER-280
nm Organic
isolation
method
-
ANSWER-1.
Lyse
2.
Add
phenol/
chloroform
>
vortex/spin
3.
Transfer
aqueous
layer
(top)
to
new
tube
4.
Add
chloroform:IAA
(removes
phenol)
>
vortex/spin
5.
Transfer
aqueous
layer
to
new
tube
6.
Add
NaOAc
and
EtOH
>
vortex/spin
7.
Decant
8.
Resuspend
How
do
you
inactivate
RNases?
-
ANSWER-200C
for
2
hrs
30
min
in
1M
NaOH
or
quanidinum
isothiocyanate
Hybridization
-
ANSWER-2
ssDNA
molecules
of
comp
base
sequence
can
form
a
ds
hybrid
(duplex)
What
does
the
incubation
step
in
hybridization
do?
-
ANSWER-Allows
formation
of
ds
molecules
Blocking
DNA
(Hybridization)
-
ANSWER-minimizes
probe
binding
to
nonspecific
sequence
ie
salmon
sperm
DNA,
Human
LINE-1
Blocking
Proteins
(Hybridization)
-
ANSWER-minimize
nonspecific
binding
of
probe
to
membrane
ie
casein
(milk),
Denhardt's
sol
Stringency
-
ANSWER-conditions
of
hybridization
that
control
the
specificity
of
binding
of
the
probe
to
the
target
sequence
How
can
you
increase
strigency
in
a
hybridization?
-
ANSWER-decrease
[salt]
increase
[formamide]
increase
temp
Formamide
acts
as
a
__________
in
a
hybridization.
-
ANSWER-denaturing
agent
Line
Probe
Assay
(LiPA)
-
ANSWER-reverse
hybridization
assay
using
sequence-specific
oligonucleotide
probes
(reverse
SSOP)
multi-parameter
testing
-->
single
strip
Line
Probe
Assay
steps
-
ANSWER-1.
Isolate
nucleic
acid
(RNA)
2.
Amplify
3.
Hybridization
4.
Strigent
wash
5.
Incubate
with
conjugate
6.
Incubate
with
substrate