Which frequently lead to the formation of thymine dimers in the DNA chain（）
A. Intercalating agents
B. Ultraviolet radiation
C. Base analogs
D. Nitrite
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When bacterial replication introduces a mismatch into double stranded DNA, the mismatch repair system（）
A. changes both the parental strand and the newly synthesized strand
B. corrects the mismatch by changing the newly synthesized unmethylated strand
C. corrects the mismatch by changing the parental strand
D. corrects the strand which is methylated
Okazaki fragments are（）
A. the smallest subunits of DNA polymerase III
B. short stretches of DNA formed on the lagging strand
C. short RNA primers needed for initiation of polymerization
D. fragments of DNA polymerase I that lack 5′ → 3′ exonuclease activity
The elongation of the lagging strand during DNA synthesis（）
A. In the 3’ to 5’ direction
B. Produces Okazaki fragments
C. Polymerizes in the direction of fork movement
Does not require a template strand
Functions of DNA polymerases and accessory proteins in eukaryotic DNA replication include（）
A. PCNA protein, a sliding clamp unit for DNA
B. DNA polymerase α, initiation the synthesis of new strands
C. RPA protein, and equivalent of SSB proteins in bacteria
D. All of the above
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