Which one of the following statements regarding DNA replication is correct ? The

Question

Which one of the following statements regarding DNA replication is correct?

There is typically only one ori in eukaryotes.
Synthesis of new DNA occurs on both parent strands in both directions away from the ori.
Strands are kept apart by helicase enzymes.
Strands are separated by topoisomerases.
Bacterial chromosomes often have a few million base pairs and several ori.

Which one of the following [molecule::description] pairings is correct?

Okazaki fragment :: small fragment of DNA on leading strand
DNA Polymerase I :: removing RNA nucleotides

Helicase :: keeping DNA strands separated

DNA Polymerase III :: removing RNA nucleotides in a 5' to 3' direction

Endonuclease :: removing nucleotides from the end of a DNA chain

If DNA replication is dispersive, then the Meselson and Stahl experiment would show what after one round of replication?

Two bands of DNA, one that is heavy and one that is light
Two bands of DNA, one that is half heavy and half light, and one that is light
One band of DNA that is half heavy and half light
Three bands of DNA, one that is light, one that is heavy, and one that is half heavy and half light
One band of DNA that is heavy

Which one of the following statements about origins of replication is correct?

Origins of replication are found only in euchromatin because euchromatin is decondensed enough to undergo replication.
Instead of origins of replication, prokaryotes have prominent binding sites for primase to signal where replication should start.
Eukaryotes have multiple origins of replication in their genomes.
DNA is naturally single stranded at the ori.
Single-stranded DNA binding proteins (SSBs) unwind DNA at the origin of replication.

Explanation / Answer

1. Synthesis of DNA occurs in both direction from Ori and form a replication bubble. Replication occursoonoboth the strands in 5'-3' direction. 2nd statement is correct.

2. DNA polymerase has proof reading activity and remove RNA primer and fills the gap. Statement 2 is correct .

3. In dispresive type of replication two bands are observed half heavy and half light. In this type the strands are not completly perental and not new. Statemement 2 is correct.

4. Eukaryotic DNA has multiple ori and are called ARS (Autonomous replicating sequence). Statement 3 is correct.

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