1. In DNA replication, DNA polymerase III cannot attach nucleotides directly to
ID: 53704 • Letter: 1
Question
1.
In DNA replication, DNA polymerase III cannot attach nucleotides directly to a chain that is already paired with the parent strand. It attaches them to an RNA primer, and they are later attached to the parent chain.
True
False
2.
Replication on the leading strand occurs away from the replication fork instead of toward it.
True
False
3.
The single-strand binding protein is needed in DNA replication because without the single-strand binder, the single strand might be cleaved or re-annealed.
True
False
4.
DNA gyrase can relieve the torsional strain caused by unwinding and prevent transformation.
True
False
5.
DNA polymerase I, unlike the other DNA polymerases, has 5 to 3 exonuclease activity that is essential during lagging strand replication to:
A. remove damaged Okazaki fragments.
B. repair damaged template DNA.
C. degrade template DNA.
D. remove the RNA primers.
E. remove overlapping segments of Okazaki fragments.
6.
What statement best describes why DNA replication requires a helicase enzyme?
A. The newly created daughter strand needs to be wound into a double helix.
B. Separation of parental DNA strands creates positive supercoils in front of the fork.
C. Complementary strands of the parental DNA need to be separated to create new daughter strands.
D. Primers need to base-pair with the template for synthesis to begin.
E. Single-strands of DNA because hydrophobic bases are exposed to water.
7.
Match the following
1. The DNA strand on which replication occurs continuously from one initial primer.
2. The partial unwinding of a DNA double helix to form two single stands where the replisome is formed.
3. The ability of a polymerase to remain attached to a template, primarily due to the action of the subunit.
4. The DNA strand where replication occurs discontinuously and requires multiple priming events.
5. Short sections of DNA synthesized discontinuously and then ligated together.
A. processivity
B. replication fork
C. Okazaki fragments
D. leading strand
E. lagging strand
8.
Match the following
1. A multiprotein complex containing a primosome and two DNA pol III enzymes capable of DNA replication.
2. Enzymes that can break phosphodiester bonds between nucleotides internally.
3. Enzymes that can chew away at an end of a DNA molecule.
4. The topological state of the DNA that determines how the double helix coils in space.
5. A single functional unit consisting of the complete chromosome plus the origin in prokaryotes.
A. supercoiling
B. exonuclease
C. endonuclease
D. replicon
E. replisome
9.
What statements are correct in describing initiation of bacterial replication? Check all that apply.
It initiates at an oriC sequence.
Two separate replisomes are loaded at the origin.
The strands are separated at GC-rich regions.
Replication proceeds bidirectionally.
There is one unique termination site.
Explanation / Answer
1. False
2. False
Replication on the leading strand occurs towards the fork not away from it.
3. True
Re-annealing is prevented by single-strand binding protein.
4. False
The given function is performed by topoisomerases not by DNA gyrase.
5. D. remove the RNA primers.
The RNA primer of adjacent fragment is removed
6. C.
Whne parental strands are separated then daughter strands are able to replicate and be copied.
7.The terms are matched as follows:
1. D, 2. B, 3. A, 4. E, 5. C
8. The terms are matched as follows:
1. E, 2. C, 3. B, 4. A, 5. D
9. All the statements are correct except the statement that strands get separated at regions which are GC-rich.
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