CLEP Biology DNA Structure and Replication 2

Question 1

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Answer

Helicase breaks hydrogen bonds between base pairs to unwind and separate the two DNA strands at the replication fork.

Question 2

What is the term for the short RNA sequences that initiate DNA synthesis?

Accepted Answer

Primers

Answer

Primers are short RNA sequences synthesized by primase that provide a free 3'-OH end for DNA polymerase to begin adding nucleotides.

Question 3

The leading strand is synthesized continuously because it grows in the same direction as:

Accepted Answer

The replication fork movement

Answer

The leading strand is synthesized continuously in the 5' to 3' direction toward the replication fork, matching its direction of movement.

Question 4

Which of the following correctly describes the antiparallel nature of DNA?

Accepted Answer

One strand runs 5' to 3' while the complementary strand runs 3' to 5'

Answer

Antiparallel means the two strands of DNA run in opposite directions: one 5'→3' and its complement 3'→5'.

Question 5

Chargaff's rules state that in any DNA molecule:

Accepted Answer

A + G = C + T

Answer

Chargaff's rules state that %A = %T and %G = %C, which means the total purines (A+G) equal total pyrimidines (C+T).

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