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WorksheetsDNA Replication and Repair Quiz
Total questions: 13
Worksheet time: 7mins
An antiviral drug mimics a nucleoside but lacks the 3' hydroxyl group on its sugar. Why does this inhibit viral replication?
It prevents nitrogenous base pairing.
It causes deamination of bases.
It destroys the hydrogen bonds in DNA.
It blocks phosphodiester bond formation.
Why do most DNA-binding proteins interact with the major groove rather than the minor groove?
The major groove is chemically distinct and exposes more functional groups
The minor groove has more exposed hydrogen bond donors/acceptors
The major groove has fewer steric hindrances
The minor groove is unstable
A researcher digests chromatin with MNase and finds ~160 bp DNA fragments. What does this indicate?
The DNA is completely degraded
The fragments represent linker DNA between nucleosomes
The fragments represent nucleosome-protected DNA
The DNA is single-stranded
A student is asked to identify the directionality of a DNA strand. Which feature should they examine?
Base sequence
Sugar-phosphate backbone
Presence of grooves
Hydrogen bonds
A mutation in primase that produces RNA primers too short (<3 bases) will cause:
More accurate replication
Faster elongation rate
Excessive Okazaki fragment length
Inability of DNA Pol to initiate synthesis
Why is the lagging strand looped during replication?
To prevent torsional stress and double stranded breaks
To increase proofreading
To allow both polymerases to move in the same direction
To permit helicase to bind
Why must helicase loading occur in G1 and not S phase?
DNA is most relaxed in G1
MCM is only expressed in G1
High CDK activity in S phase
Ligase is inactive otherwise
A tumor cell line treated with PCNA inhibitors shows reduced growth. Why?
PCNA is not required in normal cells
Tumor cells replicate faster and are more dependent on PCNA
PCNA repairs DNA damage only in tumors
PCNA prevents apoptosis
Why can’t conventional DNA Pol fully replicate chromosome ends?
No helicase at ends
PCNA does not load at ends
Leading strand cannot initiate synthesis
Primer removal leaves a gap at the 3′ end of lagging strand
Cancer cells often upregulate telomerase. Why?
To maintain chromosome ends
To increase replication fidelity
To remove RNA primers
To repair double-strand breaks
A Pol δ mutant with defective proofreading causes primarily:
Errors in mitochondrial DNA
Errors in lagging strand synthesis
Errors in leading strand synthesis
Inability to replicate origins
Which DNA Pol initiates both strands in eukaryotes?
Pol α/primase
Pol δ
Pol ε
Pol γ
Which of the following is true?
The left-hand polymerase has high processivity, the right-hand has low processivity
The left-hand polymerase has low processivity, the right-hand has high processivity
Both polymerases have equal processivity
Neither polymerase is functional
