1
MSAP Week 1- Biochemistry, Anatomy,
and Physiology Questions and Correct
Answers
OriC Answer: consists of 245 bp site of replication on
the ProK DNA and contains the 13-mer and 9-mer
sequences.
What 2 important sequences are located on the OriC?
Answer: Three 13-mer in tandem array and four 9-
mer
What does the DnaA bind? Answer: The 9-mer
sequence of DNA on ProK.
What is the significance of the DNA sequences at the
OriC? Answer: They are A-T rich, which is weaker
than G-C, at the 13-mer sequences, which makes
strands easier to separate.
What is DnaC? Answer: Helicase inhibitor (DnaC)
delivers DnaB to the template (ProK replication) then is
released
Pretest - Stuvia US
,2
What is DnaB? Answer: Helicase (ProK replication)
that binds at the replication fork on each single strand
and continues to unwind DNA away from origin. Also,
binds to primase to form primosome.
What is DnaA? Answer: initiator proteins that bind to
the 9 mer sequence in Prok and breaks H-bonds at
OriC.
single stranded binding protein (ssb) Answer: binds
to single stranded DNA in the replication bubble and
prevents it from re-annealing or forming secondary
structure
Primase Answer: adds a primer made of about 5-10
bp of RNA (uses DNA template) to which DNA
polymerase III bind.
What is the primasome? Answer: DnaB (helicase) and
primase
DNA poly III Answer: Polymerizes and elongates DNA
in a 5'-3' manner (phosphodiester bond between 5'
phosphate group and 3' hydroxyl group). The addition
Pretest - Stuvia US
,3
of a dNTP releases a pyrophosphate. Also has
exonuclease ability in a 3'-5'
DNA poly 1 Answer: removes and replaces RNA
primer with DNA nucleotides
Ligase Answer: ligates the Okazaki fragments and
nicks in the new DNA strands
Topoisomerase Answer: corrects "overwinding" ahead
of replication forks (upstream) by breaking, swiveling,
and rejoining DNA strands and adds negative supercoils
upstream of replication (gyrase in prok)
What is sigma factor? Answer: in ProK, it is part of
the holoenzyme (included with RNA polymerase).
- only needed to initiate transcription not necessary for
transcribing
What does RNA poly I make? Answer: 5.8S, 18S, 28S
rRNA
What does RNA poly II make? Answer: mRNA and
some snRNA
Pretest - Stuvia US
, 4
What does RNA poly III make? Answer: tRNA and
some snRNA
What are the regions of the ProK gene? Answer: -
promoter- located upstream of the gene to ensure
proper location of transcription initiation
- RNA coding sequence- the portion of DNA that will be
transcribed into RNA
- terminator- located downstream from the gene that
once transcribed (forms hairpins and stem loops due to
palindromic and G-C rich regions) stops transcription
What are the promoter sequences in ProK for
transcription? Answer: -35 and -10 (Pribnow box)
consensus sequences
What are the promoter sequences for EuK
transcription? Answer: GC box
TATA box
CAAT box
Pretest - Stuvia US
MSAP Week 1- Biochemistry, Anatomy,
and Physiology Questions and Correct
Answers
OriC Answer: consists of 245 bp site of replication on
the ProK DNA and contains the 13-mer and 9-mer
sequences.
What 2 important sequences are located on the OriC?
Answer: Three 13-mer in tandem array and four 9-
mer
What does the DnaA bind? Answer: The 9-mer
sequence of DNA on ProK.
What is the significance of the DNA sequences at the
OriC? Answer: They are A-T rich, which is weaker
than G-C, at the 13-mer sequences, which makes
strands easier to separate.
What is DnaC? Answer: Helicase inhibitor (DnaC)
delivers DnaB to the template (ProK replication) then is
released
Pretest - Stuvia US
,2
What is DnaB? Answer: Helicase (ProK replication)
that binds at the replication fork on each single strand
and continues to unwind DNA away from origin. Also,
binds to primase to form primosome.
What is DnaA? Answer: initiator proteins that bind to
the 9 mer sequence in Prok and breaks H-bonds at
OriC.
single stranded binding protein (ssb) Answer: binds
to single stranded DNA in the replication bubble and
prevents it from re-annealing or forming secondary
structure
Primase Answer: adds a primer made of about 5-10
bp of RNA (uses DNA template) to which DNA
polymerase III bind.
What is the primasome? Answer: DnaB (helicase) and
primase
DNA poly III Answer: Polymerizes and elongates DNA
in a 5'-3' manner (phosphodiester bond between 5'
phosphate group and 3' hydroxyl group). The addition
Pretest - Stuvia US
,3
of a dNTP releases a pyrophosphate. Also has
exonuclease ability in a 3'-5'
DNA poly 1 Answer: removes and replaces RNA
primer with DNA nucleotides
Ligase Answer: ligates the Okazaki fragments and
nicks in the new DNA strands
Topoisomerase Answer: corrects "overwinding" ahead
of replication forks (upstream) by breaking, swiveling,
and rejoining DNA strands and adds negative supercoils
upstream of replication (gyrase in prok)
What is sigma factor? Answer: in ProK, it is part of
the holoenzyme (included with RNA polymerase).
- only needed to initiate transcription not necessary for
transcribing
What does RNA poly I make? Answer: 5.8S, 18S, 28S
rRNA
What does RNA poly II make? Answer: mRNA and
some snRNA
Pretest - Stuvia US
, 4
What does RNA poly III make? Answer: tRNA and
some snRNA
What are the regions of the ProK gene? Answer: -
promoter- located upstream of the gene to ensure
proper location of transcription initiation
- RNA coding sequence- the portion of DNA that will be
transcribed into RNA
- terminator- located downstream from the gene that
once transcribed (forms hairpins and stem loops due to
palindromic and G-C rich regions) stops transcription
What are the promoter sequences in ProK for
transcription? Answer: -35 and -10 (Pribnow box)
consensus sequences
What are the promoter sequences for EuK
transcription? Answer: GC box
TATA box
CAAT box
Pretest - Stuvia US
