AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

DNA REPLICATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which of the following help(s) to hold the DNA strands apart while they are being replicated?
A
RNA primase
B
single-strand binding proteins
C
DNA polymerase I
D
DNA ligase
Explanation: 

Detailed explanation-1: -DNA Helicases-These proteins bind to the double stranded DNA and stimulate the separation of the two strands.

Detailed explanation-2: -Proteins called Binding Proteins keep the two DNA strands apart preserving the Replication Fork.

Detailed explanation-3: -To unwind DNA, helicase first binds to DNA and then cleaves the hydrogen bonds connecting base pairs to separate the strands of the helix. Then single-stranded binding protein attaches to the single-stranded DNA. Helicase unwinds the DNA helix and SSB protein keeps the strands apart.

Detailed explanation-4: -Small molecules called single-stranded binding proteins (SSB) attach to the loose strands of DNA to keep them from re-forming the hydrogen bonds that helicase just broke apart. Figure 5.4. 2 Helicase unwinds and unzips the DNA molecule. SSB keep the two strands from re-attaching to one another.

Detailed explanation-5: -Figure 9.4 General Overview of a DNA Replication Fork. Two replication forks are formed by the opening of the double-stranded DNA at the origin, and helicase separates the DNA strands, which are coated by single-stranded binding proteins to keep the strands separated. DNA replication occurs in both directions.

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