DNA Structure and Replication

These flashcards cover key vocabulary terms related to the structure and replication of DNA.

Nucleotide

The basic building block of nucleic acids, consisting of a phosphate group, a sugar, and a nitrogenous base.

Phosphodiester bond

The bond that connects nucleotides together in a polynucleotide strand.

Polynucleotide

A chain of nucleotides; can refer to DNA or RNA strands.

Three prime end (3')

The end of a nucleic acid strand where a new nucleotide can be added.

Five prime end (5')

The opposite end of the nucleic acid strand; cannot have new nucleotides added here.

Base pairing rules

The rules stating that adenine pairs with thymine, and guanine pairs with cytosine.

Antiparallel

Term describing the opposite orientation of the two strands of DNA.

Hydrogen bond

The bond that forms between complementary nitrogenous bases in DNA strands.

Leading strand

The DNA strand that is synthesized continuously towards the replication fork.

Lagging strand

The DNA strand that is synthesized in fragments away from the replication fork.

Okazaki fragments

Short segments of DNA synthesized on the lagging strand during DNA replication.

Primase

An enzyme that synthesizes a short RNA primer to initiate DNA synthesis.

DNA polymerase III

The enzyme responsible for adding nucleotides to the growing DNA strand during replication.

RNA primer

A short strand of RNA that provides the starting point for DNA synthesis.

DNA ligase

An enzyme that connects Okazaki fragments on the lagging strand by forming phosphodiester bonds.

Semi-conservative replication

The method of DNA replication where each new DNA molecule consists of one original strand and one new strand.

Helicase

An enzyme that unwinds and separates the two strands of DNA during replication.

Topoisomerase

An enzyme that relieves tension in the DNA helix ahead of the replication fork.