DNA Replication Fundamentals Practice Quiz (9 questions)

Explanation

Helicase is the enzyme that unwinds the DNA double helix at the replication fork, separating the two strands to allow replication to proceed. DNA polymerase synthesizes new DNA strands, ligase joins fragments, and primase synthesizes RNA primers.

Explanation

The leading strand is synthesized continuously in the 5' to 3' direction, following the replication fork. The lagging strand is synthesized discontinuously in Okazaki fragments, also in the 5' to 3' direction, but in segments opposite to the fork movement.

Explanation

In DNA, the base pairing follows specific rules: adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). These pairs are stabilized by hydrogen bonds and are essential for accurate replication.

Explanation

Helicase unwinds the DNA at the replication fork, allowing for single strands to be accessible for copying. Primase synthesizes RNA primers, DNA polymerase extends new strands, and ligase joins fragments—none unwind DNA.

Explanation

DNA replication in eukaryotic cells takes place in the nucleus, while in prokaryotes, it occurs in the cytoplasm. Mitochondria have their own DNA replication, but it's not the primary location for nuclear DNA.

Explanation

Ligase joins Okazaki fragments on the lagging strand, sealing nicks in the sugar-phosphate backbone. It does not unwind DNA, synthesize primers, or proofread.

Explanation

Adenine pairs with thymine via two hydrogen bonds, whereas cytosine pairs with guanine via three hydrogen bonds, reflecting their base pairing rules.

Explanation

DNA synthesis always occurs in the 5' to 3' direction, meaning nucleotides are added to the 3' end of the growing strand.

Explanation

The leading strand is synthesized continuously toward the replication fork, while the lagging strand is synthesized discontinuously in Okazaki fragments.