12 B DNA Replication Review

These flashcards cover key terms and concepts related to DNA replication to aid in exam preparation.

Semiconservative replication

The method by which DNA is replicated in cells, where each new DNA molecule consists of one old strand and one new strand.

Heavy nitrogen

An isotope of nitrogen (N-15) used by researchers to track DNA replication.

CsCl centrifugation

A technique used by Meselson and Stahl to separate DNA based on density.

Bidirectional replication

A method of DNA replication where two replication forks proceed in opposite directions from a single origin.

Origin of replication

The specific location on the DNA where replication starts.

Replication bubble

The structural formation created when the DNA strands are separated during replication.

Replication fork

The Y-shaped region where the DNA is being unwound and replicated.

DNA polymerase

An enzyme responsible for synthesizing new DNA strands by adding nucleotides.

Single-stranded binding proteins (SSBPs)

Proteins that bind to single-stranded DNA to prevent reannealing during replication.

Primase

An enzyme that synthesizes RNA primers, necessary for DNA polymerase to begin replication.

Okazaki fragments

Short DNA fragments synthesized on the lagging strand during DNA replication.

DNA ligase

An enzyme that joins Okazaki fragments and seals gaps in the DNA.

Leading strand

The strand of DNA that is synthesized continuously during replication toward the replication fork.

Lagging strand

The strand of DNA that is synthesized discontinuously away from the replication fork, creating Okazaki fragments.

Telomeres

Repeating sequences at the ends of eukaryotic chromosomes that protect them from degradation.

Telomerase

An enzyme that adds repetitive sequences to telomeres, extending their length.

Exonuclease activity

The ability of some DNA polymerases to remove nucleotides from the ends of DNA strands.

Proofreading

The process by which DNA polymerases correct errors in DNA replication.

Holoenzyme

A multi-subunit complex of enzymes, such as DNA polymerase, that includes all necessary components for DNA synthesis.

Clamp loader

A protein complex that assembles the sliding clamp onto the DNA during replication.

PCNA (Proliferating Cell Nuclear Antigen)

A sliding clamp in eukaryotic DNA replication that enhances the processivity of DNA polymerases.

Hydrogen bonds

The weak bonds that hold together complementary base pairs in DNA.

Topoisomerase

An enzyme that helps relieve the tension in DNA by cutting and rejoining the strands during replication.

Drosophila melanogaster

Common fruit fly used as a model organism in genetics studies, including DNA replication.

5' to 3' direction

The direction in which DNA synthesis occurs, from the fifth carbon of one nucleotide to the third carbon of another.

Messer's, O and Stahl

The scientists who confirmed the semiconservative model of DNA replication.

RNA primer

Short RNA sequences synthesized by primase that provide a starting point for DNA polymerase.

Lagging strand synthesis

The process by which DNA is synthesized discontinuously, resulting in Okazaki fragments.

NTPs (Nucleotide Triphosphates)

The building blocks used by DNA polymerase to synthesize DNA strands.

3' end

The end of the DNA strand where nucleotides can be added during elongation.

5' end

The starting point during DNA strand synthesis, where the free phosphate group is located.

Hydrolyzes

The chemical process by which a water molecule is used to break a bond.

Replication origin consensus sequence

A specific sequence of nucleotides recognized by initiation proteins to start replication.

Open complex

The local unwinding of DNA at the origin of replication during the initiation of DNA replication.

Helicase

An enzyme that unwinds the DNA double helix by breaking hydrogen bonds between strands.

Primase's role

To synthesize short RNA primers that provide starting points for DNA polymerase.

Replisome

The complex of enzymes and proteins that carry out DNA replication.

Continuous synthesis

The process of synthesizing a DNA strand without interruption, as seen in the leading strand.

Discontinuous synthesis

Synthesizing DNA in short segments (Okazaki fragments) on the lagging strand.

Base pairing

The specific hydrogen bonding between adenine-thymine and guanine-cytosine in DNA.

Mutations

Changes in the DNA sequence that can occur during replication or due to environmental factors.

Cancer and telomerase reactivation

The phenomenon where cancer cells can often reactivate telomerase, allowing for unlimited divisibility.

Werner syndrome

A genetic disorder characterized by premature aging caused by mutations affecting telomerase activity.

SSBPs role

To stabilize single-stranded DNA during replication to prevent it from reforming a double helix.

Initiation of DNA replication

The first step in DNA replication involving the binding of specific proteins to the origin of replication.

Enzymatic steps in replication

A sequence of complex reactions involving various enzymes necessary for accurate DNA replication.

Directionality in replication

The essential aspect of DNA synthesis happening from the 5' to the 3' direction.

Signal for termination

The point at which DNA synthesis concludes, often at the replication forks meeting.

Role of ATP in replication

Provides energy necessary for enzyme activity, especially helicase, during DNA replication.