Unit 4 (Part III) Flashcards
(43 cards)
DNA replication is…
Semi-conservative
DNA polymerases can synthesise DNA…
by adding dNTPs to a hydroxyl group on the end of a growing polynucleotide chain hydrogen-bonded to a strand of DNA.
Short segments of newly synthesized DNA on the lagging strand of DNA are called…
Okazaki fragments.
Primase synthesizes short sequences of _______ complementary to the _______ strand.
RNA; lagging
In addition to synthesizing DNA, DNA polymerase I also has a second catalytic activity—it can…
remove RNA primers.
In eukaryotic cells, RNA primers are removed by the combined action of 5´ to 3´ exonuclease and…
RNase H
The short fragments of DNA produced during DNA replication are joined together by…
DNA ligase
Which eukaryotic DNA polymerase replicates the leading strand in a 5´ to 3´ direction?
ε (Epsilon)
Which eukaryotic DNA polymerase replicates the lagging strand in a 3´ to 5´ direction?
None of the above; the lagging strand is replicated in a 5’ to 3’ direction.
Eukaryotic DNA polymerase ε…
is the polymerase for leading-strand replication.
In E. coli, the major enzyme responsible for DNA replication is DNA polymerase…
III
Proliferating cell nuclear antigen (PCNA) is a _______ in eukaryotes.
sliding clamp protein
Free rotation of one cut DNA strand around one uncut strand is the primary function of…
topoisomerase I.
The function of topoisomerase II is to…
a. resolve DNA tangles.
b. allow DNA to swivel and unwind.
c. allow daughter chromatids to separate in anaphase.
During DNA replication, the overall error frequency is 1 in _______ base pairs.
10^9
The proofreading property of DNA polymerase is due to its _______ activity.
3´ to 5´ exonuclease
Origins of replication are the…
binding sites for the protein complex that initiates DNA synthesis.
Autonomously replicating sequences are…
yeast origins of replication.
Telomeres are the…
end-sequences of chromosomes.
Telomerase is…
a. a reverse transcriptase.
b. the enzyme that adds a unique sequence onto the ends of chromosomes.
c. an enzyme first discovered in Tetrahymena.
Point mutations in DNA result from…
a. incorporation of incorrect bases during replication.
b. changes as a result of chemical exposure.
c. changes as a result of radiation exposure.
The most common cause of skin cancer is damage to DNA by…
ultraviolet light.
Pyrimidine dimers…
a. block DNA replication and transcription.
b. can be repaired by photoreactivation.
c. can be repaired by nucleotide-excision repair.
The human disease in which affected individuals are extremely sensitive to sunlight and develop multiple skin cancers on exposed areas is called…
xeroderma pigmentosum.
