DNA & DNA replication

nucleotide

A building block of DNA, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group.

antiparallel

Strands of a DNA double helix have their nucleotides oriented in the opposite direction to one another.

DNA replication

The process in which DNA makes a duplicate copy of itself.

DNA gyrase

Enzyme that functions to reduce DNA supercoiling and relieve tension in DNA.

DNA helicase

An enzyme that unwinds the DNA double helix by breaking H bonds during DNA replication.

single-stranded binding proteins

Molecules that prevent the DNA strands from reannealing.

DNA polymerase III

Enzyme that synthesizes DNA in the 5' to 3' direction.

DNA polymerase I

Enzyme that removes the RNA primer and replaces the nucleotides with DNA.

DNA polymerase II

Enzyme that proofreads the newly synthesized DNA.

DNA ligase

Enzyme that joins Okazaki fragments.

RNA primase

Enzyme that synthesizes the RNA primer.

RNA primer

Short segment of RNA used to initiate synthesis of a new strand of DNA during replication.

leading strand

A continuously synthesized DNA strand that elongates towards the replication fork.

lagging strand

A discontinuously synthesized DNA strand that elongates in a direction away from the replication fork.

replication fork

A Y-shaped region on a replicating DNA molecule where new strands are growing.

replication bubble

Segment of a DNA molecule that is unwinding and undergoing replication.

complementary base pairing

Hydrogen bonding between specific pyrimidines and purines (adenine & thymine; cytosine & guanine)

5'

End of a DNA molecule with a free phosphate group.

3'

End of a DNA molecule with a free hydroxyl group.

double helix

The shape of DNA; referring to its two adjacent polynucleotide strands wound into a spiral shape.