Molecular Biology Terms—DNA Replication

Vocabulary flashcards related to DNA replication in Eukaryotic Cells

3’ end

The end of a DNA or RNA strand where the nucleotide has a free hydroxyl group attached to the 3’ carbon of the sugar molecule.

3’ to 5’

Orientation of a DNA strand.

5’ end

The end of a DNA or RNA strand where the nucleotide has a free phosphate group attached to the 5’ carbon of the sugar molecule.

5’ to 3’

Orientation of a DNA strand, complementary to 3’ to 5’.

Antiparallel

Complimentary base pairs running in opposite directions (3’ to 5’ pairing to 5’ to 3’).

Daughter DNA molecule

DNA molecules created during the DNA replication process that are nearly exact copies of the parental DNA helix with some mutations; contains the same generic information as the parent cells.

DNA ligase

A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3’ end of one DNA fragment to the 5’ end of another DNA fragment.

DNA polymerase I

Enzyme that primarily functions in DNA repair by removing the short RNA primer required for DNA synthesis during replication and filling in gaps in single-stranded DNA; one of three DNA polymerases used in E. coli (prokaryotic cells mainly).

DNA polymerase III

Primary enzyme complex involved in prokaryotic DNA replication and responsible for DNA replication during cell division in prokaryotes.

DNA polymerase

Generally, the enzyme that makes protein.

Helicase

An enzyme that untwists the double helix of DNA at replication forks, separating the two strands and making them available as template strands.

Lagging strand

A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5’ -> 3’ direction away from the replication fork.

Leading strand

The new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5’ -> 3’.

Nucleotides

The building blocks of DNA, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and one to three phosphate groups

Okazaki fragments

A short segment of DNA synthesized away from the replication fork on a template strand during DNA replication; segments are joined together to make up the lagging strand of newly synthesized DNA.

Origin of Replication

Site where the replication of a DNA molecule begins

Parent DNA molecule

The original DNA molecule that serves as the template for DNA replication during the process of DNA replication; one of the two strands that make up the double -helix structure of DNA and provides the blueprint for the synthesis of new, complementary DNA strands.

Primase

An enzyme that joins RNA nucleotides to make a primer during DNA replication, using the parental DNA strand as a template (makes RNA primer).

Primer

A short polynucleotide with a free 3’ end, bound by complementary base pairing to the template strand and elongated with DNA nucleotides during DNA replication (necessary to get the whole thing going).

Replication fork

A Y-shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are being synthesized.

SSB proteins

Proteins responsible for stabilizing, protecting, and transiently maintaining single DNA band obtained from the separation of the duplex DNA band by action of helicase proteins.

Template (strand)

The blueprint parent DNA strands that are used to make the daughter DNA strands

Topoisomerase

A protein that breaks, swivels, and rejoins DNA strands