review for DNA

Summery of DNA replication in Prokaryotic

-DNA unwinds at the origin of replication. -Helicase opens up the DNA-forming replication forks; these are extended in both directions. -Single-strand binding proteins coat the ---DNA around the replication fork to prevent rewinding of the DNA. -Topoisomerase binds at the region ahead of the replication fork to prevent supercoiling (over-winding). -Primase synthesizes RNA primers complementary to the DNA strand. -DNA polymerase III starts adding nucleotides to the 3′-OH (sugar) end of the primer. -Elongation of both the lagging and the leading strand continues. -RNA primers are removed and gaps are filled with DNA by DNA pol I. -The gaps between the DNA fragments are sealed by DNA ligase.

What enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?

DNA polymerase

Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction?

DNA polymerase III

A new DNA strand elongates only in the 5' to 3' direction because

DNA polymerase can only add nucleotides to the free 3' end.

sliding clamp

Holds DNA polymerase in place during strand extension

During replication what is a main difference between Eukaryotic and Prokaryotic

Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

Pol III in both eukayotic and prokarotic

add nucleoteds

single strand binding proteins

bind to the unpaired DNA strands, keeping them from re-pairing

What enzymes separates the DNA strands during replication

helicase

Poll II

is used primarily required for repair

Which of the enzymes covalently connects segments of DNA?

ligase

During replication what is a main difference between Eukaryotic and Prokaryotic

n prokaryotic cells, there is only one point of origin, replication occurs in two opposing directions at the same time, and takes place in the cell cytoplasm. Eukaryotic cells on the other hand, have multiple points of origin, and use unidirectional replication within the nucleus of the cell.

Which of the enzymes synthesizes short segments of RNA?

primase

poly 1

removes RNA primer and replaces with newly synthesized DNA

Which of the following help(s) to hold the DNA strands apart while they are being replicated?

single-strand binding proteins

The leading and the lagging strands differ in that ?

the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.