1) Single-strand nicks made by ________________________separate the two strands
ID: 317034 • Letter: 1
Question
1) Single-strand nicks made by ________________________separate the two strands in a DNA molecule in the absence of rotation.
type II topoisomerases
type I topoisomerases
single strand breaking proteins (SSBs)
displacement enzymes
2)
Which of the following is true?
Flap endonuclease and DNA Pol I use 5' to 3' exonuclease to remove RNA primers
Both eukaryotes and bacteria need a non-processive polymerase in order to remove RNA primers.
DNA Pol I has 3' to 5' exonuclease activity but DNA Pol III does not.
DNA Pol I uses 5' to 3' exonuclease activity to remove RNA primers but DNA Pol epsilon and DNA Pol delta do not.
a.type II topoisomerases
b.type I topoisomerases
c.single strand breaking proteins (SSBs)
d.displacement enzymes
Explanation / Answer
Question number 1 : The correct answer is B ( type I topoisomerase)
Explanations : There are two classes of topoisomerases. Type I topoisomerases act by transiently breaking one of the two DNA strands, passing the unbroken strand through the break, and rejoining the broken ends; they change Lk in increments of 1. Type II topoisomerases break both DNA strands and change Lk in increments of 2.
Lk : Linking number
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