BIO 340 Unit 1 Exam Questions And Answers
With Verified Solutions Graded A+ Latest Update
2025.
What are the consequences of replisome function at each fork in a circular chromosome with no free
ends? - ANSWER Super coiling
How do bacterial cells cope with the consequences of super coiling? - ANSWER Gyrase
How do viruses make copies of circularized viral genomes? - ANSWER Rolling circle
replication
Nick in phosphodiester backbone of one of two strands produces free _____ end for continuous "rolling"
DNA synthesis using the still circular strand as a template - ANSWER 3'
Free ____ end on nicked strand unrolls and serves as template for discontinuous synthesis that yields
Okazaki fragments - ANSWER 5'
Rolling circle replication produces multiple copies of original molecule linked end to end as a single
linear ______ - ANSWER Concatamer
Steps of rolling circle replication (1.-4.) - ANSWER 1. Nick is made in one of two strands of
the parental duplex
2. The 5' end is displaced and covered by SSBs
3. Polymerization at the 3' end adds new deoxyribonucleotides
4. Attachment of replisome and formation of Okazaki fragments
How many origins of replication does a circular bacterial chromosome contain? - ANSWER
One
True or False, eukaryotic chromosomes contain multiple origins of replication. - ANSWER
True
Stretches of DNA between the fusion points for replication forks that merge on either side of an origin of
replication - ANSWER Replicons
True or false, replicons are smaller in size in eukaryotes than they are in prokaryotes. - ANSWER
True
During which phase of the cell cycle does DNA synthesis take place? - ANSWER S phase
Origins of replication are bound during G1 by a multisubunit ___________ that consists of licensing
factors, helicase subunits, and other regulators - ANSWER Origin recognition complex (ORC)
, Progression to S phase activates ORC components to unwind DNA for synthesis coordinately at all
________ - ANSWER Pre-RC elements
True or false, eukaryotes may have 15 or more different DNA polymerases - ANSWER True
Polymerases used for priming synthesis - ANSWER pol α/primase
Polymerase used for building the leading strand - ANSWER pol ∈
Polymerase used for building the lagging strand - ANSWER pol δ
Extended region of template made by telomerase - ANSWER Telomere
Must be removed from the parent helix and added to the daughter helices during DNA replication -
ANSWER Histone proteins
The ultimate characterization of a nucleic acid is to determine its precise sequence of __________ -
ANSWER Nucleotide bases
1st generation method of DNA sequencing - ANSWER dideoxy "chain termination" sequencing
Uses DNA polymerase to replicate new DNA from a single-stranded template - ANSWER
Dideoxynucleotide sequencing
Each dideoxynucleotide sequencing reaction contains an excess of the four standard dNTPs, plus a small
amount of one dideoxynucleotide (ddCTP), which lacks a - ANSWER 3'-OH group
True or false, a separate reaction is carried out for A, T, G, and C, using the corresponding small amount
of ddNTP - ANSWER True
Whenever a ddNTP is incorporated into the product DNA molecule - ANSWER Replication
ceases
Replication ceases whenever a ddNTP is incorporated into the product DNA molecule; thus, each reaction
tube produces a series of DNA molecules of varying lengths that can be sorted by size via -
ANSWER Gel electrophoresis
How does a dideoxynucleotide function as a "chain terminator" when it's incorporated into a newly-
synthesized strand of DNA? - ANSWER It lacks a 3'-OH linkage group, so it cannot form a
phosphodiester bond
In ________ an image (autoradiograph) of the gel is made by exposing the gel to x-ray film -
ANSWER Manual sequencing
In manual sequencing, why are the bands in the autoradiograph visible? - ANSWER Because
primers that began each fragment were labeled with radioactive 32p
The _____ bands are the DNA products closest to the primer and these travel _____ on the gel -
ANSWER shortest; fastest
In manual sequencing, the gel is read in what direction? - ANSWER Bottom up, all four lanes
together
In _______, a laser is used to excite four different fluorescent tags added separately to each of the
ddNTPs; the output is a chromatogram - ANSWER Automated sequencing
With Verified Solutions Graded A+ Latest Update
2025.
What are the consequences of replisome function at each fork in a circular chromosome with no free
ends? - ANSWER Super coiling
How do bacterial cells cope with the consequences of super coiling? - ANSWER Gyrase
How do viruses make copies of circularized viral genomes? - ANSWER Rolling circle
replication
Nick in phosphodiester backbone of one of two strands produces free _____ end for continuous "rolling"
DNA synthesis using the still circular strand as a template - ANSWER 3'
Free ____ end on nicked strand unrolls and serves as template for discontinuous synthesis that yields
Okazaki fragments - ANSWER 5'
Rolling circle replication produces multiple copies of original molecule linked end to end as a single
linear ______ - ANSWER Concatamer
Steps of rolling circle replication (1.-4.) - ANSWER 1. Nick is made in one of two strands of
the parental duplex
2. The 5' end is displaced and covered by SSBs
3. Polymerization at the 3' end adds new deoxyribonucleotides
4. Attachment of replisome and formation of Okazaki fragments
How many origins of replication does a circular bacterial chromosome contain? - ANSWER
One
True or False, eukaryotic chromosomes contain multiple origins of replication. - ANSWER
True
Stretches of DNA between the fusion points for replication forks that merge on either side of an origin of
replication - ANSWER Replicons
True or false, replicons are smaller in size in eukaryotes than they are in prokaryotes. - ANSWER
True
During which phase of the cell cycle does DNA synthesis take place? - ANSWER S phase
Origins of replication are bound during G1 by a multisubunit ___________ that consists of licensing
factors, helicase subunits, and other regulators - ANSWER Origin recognition complex (ORC)
, Progression to S phase activates ORC components to unwind DNA for synthesis coordinately at all
________ - ANSWER Pre-RC elements
True or false, eukaryotes may have 15 or more different DNA polymerases - ANSWER True
Polymerases used for priming synthesis - ANSWER pol α/primase
Polymerase used for building the leading strand - ANSWER pol ∈
Polymerase used for building the lagging strand - ANSWER pol δ
Extended region of template made by telomerase - ANSWER Telomere
Must be removed from the parent helix and added to the daughter helices during DNA replication -
ANSWER Histone proteins
The ultimate characterization of a nucleic acid is to determine its precise sequence of __________ -
ANSWER Nucleotide bases
1st generation method of DNA sequencing - ANSWER dideoxy "chain termination" sequencing
Uses DNA polymerase to replicate new DNA from a single-stranded template - ANSWER
Dideoxynucleotide sequencing
Each dideoxynucleotide sequencing reaction contains an excess of the four standard dNTPs, plus a small
amount of one dideoxynucleotide (ddCTP), which lacks a - ANSWER 3'-OH group
True or false, a separate reaction is carried out for A, T, G, and C, using the corresponding small amount
of ddNTP - ANSWER True
Whenever a ddNTP is incorporated into the product DNA molecule - ANSWER Replication
ceases
Replication ceases whenever a ddNTP is incorporated into the product DNA molecule; thus, each reaction
tube produces a series of DNA molecules of varying lengths that can be sorted by size via -
ANSWER Gel electrophoresis
How does a dideoxynucleotide function as a "chain terminator" when it's incorporated into a newly-
synthesized strand of DNA? - ANSWER It lacks a 3'-OH linkage group, so it cannot form a
phosphodiester bond
In ________ an image (autoradiograph) of the gel is made by exposing the gel to x-ray film -
ANSWER Manual sequencing
In manual sequencing, why are the bands in the autoradiograph visible? - ANSWER Because
primers that began each fragment were labeled with radioactive 32p
The _____ bands are the DNA products closest to the primer and these travel _____ on the gel -
ANSWER shortest; fastest
In manual sequencing, the gel is read in what direction? - ANSWER Bottom up, all four lanes
together
In _______, a laser is used to excite four different fluorescent tags added separately to each of the
ddNTPs; the output is a chromatogram - ANSWER Automated sequencing
