DNA Replication

Semiconservative model

Type of DNA replication where each new DNA molecule consists of one old and one new strand.

Replication fork

Y-shaped region at the end of a replication bubble where DNA strands are being separated.

Helicase

Enzyme that unwinds the DNA double helix at the replication fork.

Single-strand binding proteins

Proteins that bind to and stabilize single-stranded DNA, preventing rejoining.

Topoisomerase

Enzyme that alleviates supercoiling ahead of the replication fork by cutting and rejoining DNA strands.

DNA primase

Enzyme that synthesizes a short RNA primer complementary to a DNA template.

DNA polymerase

Enzyme that synthesizes new DNA strands by adding nucleotides complementary to the template strand.

Leading strand

The DNA strand synthesized continuously in the same direction as the replication fork.

Lagging strand

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

Okazaki fragments

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

DNA ligase

Enzyme that joins Okazaki fragments together on the lagging strand.

Proofreading DNA

The process by which DNA polymerase corrects errors in newly synthesized DNA.

Telomeres

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

Telomerase

Enzyme that elongates telomeres, found in germ cells and some stem cells.

Origin of replication

Specific site in the DNA where replication begins.

Replication bubble

The area where the DNA strands are separated and replication occurs.

dNTPs

Deoxynucleotide triphosphates, the building blocks for DNA synthesis.

RNA primer

Short strand of RNA that provides a starting point for DNA synthesis.

3' to 5' template

Direction in which DNA polymerase reads the DNA template strand to synthesize a new strand in the 5' to 3' direction.

Eukaryotic genome

A genome that consists of multiple linear chromosomes.

Prokaryotic genome

A genome that consists of a single, circular chromosome.

PCR (Polymerase Chain Reaction)

Technique used to amplify specific DNA sequences through repeated cycles of denaturation, annealing, and elongation.

Mg2+ (Magnesium ions)

Cofactor that stabilizes DNA polymerase and is essential for its activity.

Denaturation temperature

The temperature (usually around 95°C) at which the double-stranded DNA separates into single strands.

Annealing temperature

The temperature at which primers bind to the DNA template during PCR.

Extension temperature

The temperature at which DNA polymerase synthesizes new DNA strands during PCR.

Genetic material

The molecule (DNA or RNA) that carries genetic information.

Base pairing

The specific hydrogen bonding between nucleotides, A with T and C with G in DNA.

DNA template strand

The strand of DNA that serves as a guide for the synthesis of a new strand.

Complementary strand

The newly synthesized DNA strand that pairs with the template strand.

Genetic replication

The process by which DNA makes a copy of itself.

Nucleotide

The basic building block of DNA and RNA, consisting of a sugar, phosphate group, and a nitrogenous base.

Deoxyribonucleic acid (DNA)

Molecule that carries the genetic instructions used in growth, development, and reproduction.

Ribonucleic acid (RNA)

Molecule that plays roles in coding, decoding, regulation, and expression of genes.

Chromosome

Structure made of DNA and proteins that contains genetic information.

Transcription

Process by which RNA is synthesized from a DNA template.

Replication accuracy

A measure of how correctly DNA is replicated, with an error rate of 1 error per 10 billion nucleotides.

Gene expression

The process by which the information in a gene is used to produce a functional gene product, typically a protein.

Mutation

Permanent alteration in the DNA sequence that may lead to changes in phenotype.

DNA damage repair

Cellular mechanisms that identify and correct damage to the DNA molecules.

Cell cycle

The series of phases that cells go through as they grow and divide.

S phase

The phase of the cell cycle in which DNA is replicated.

Cell division

The process by which a parent cell divides into two or more daughter cells.

Biochemical pathway

A series of chemical reactions that occur within a cell.