DNA: The Molecular Basis of Inheritance

Vocabulary flashcards related to DNA structure, function, replication, and repair based on lecture notes.

DNA

Deoxyribonucleic acid, the genetic material that carries hereditary information.

Nucleotide

The building block of a nucleic acid, consisting of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

Deoxyribose

The 5-carbon sugar found in DNA nucleotides.

Nitrogenous Base

A component of nucleotides; in DNA, these include adenine (A), thymine (T), cytosine (C), and guanine (G).

Phosphodiester Bond

The bond that links nucleotides together in a DNA strand, formed between the phosphate group of one nucleotide and the 3'-OH of the next nucleotide.

Chargaff's Rules

The rules stating that the amount of adenine equals the amount of thymine and the amount of cytosine equals the amount of guanine in a DNA molecule.

X-ray Crystallography

A technique used to determine the three-dimensional structure of molecules by analyzing the diffraction pattern of X-rays passing through a crystal.

Double Helix

The structure of DNA, consisting of two strands wound around each other.

Antiparallel

The arrangement of DNA strands in a double helix, where one strand runs 5' to 3' and the other runs 3' to 5'.

Semiconservative Model

The model of DNA replication in which each daughter molecule has one old strand (derived from the parent) and one newly made strand.

Origins of Replication

Specific sites on a DNA molecule where replication begins.

Replication Fork

The Y-shaped region where new DNA strands are elongating during replication.

Helicase

An enzyme that untwists the double helix at replication forks.

Single-Strand Binding Proteins

Proteins that bind to and stabilize single-stranded DNA during replication.

Topoisomerase

An enzyme that relieves overwinding strain ahead of replication forks by breaking, swiveling, and rejoining DNA strands.

Primase

An enzyme that synthesizes an RNA primer to initiate DNA synthesis.

RNA primer

A short RNA sequence that is used to start DNA synthesis.

DNA Polymerase

An enzyme that catalyzes the elongation of new DNA by adding nucleotides to the 3' end of an existing strand.

Leading Strand

The new DNA strand synthesized continuously along the template strand toward the replication fork in the 5' to 3' direction.

Lagging Strand

The new DNA strand synthesized discontinuously in segments (Okazaki fragments) away from the replication fork.

Okazaki Fragments

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

DNA Ligase

An enzyme that joins Okazaki fragments together on the lagging strand or joins the 3' end of DNA that replaces the primer to the rest of the leading strand.

Proofreading

The process by which DNA polymerases remove and replace incorrect nucleotides during replication.

Mismatch Repair

A repair system that corrects errors in base pairing after replication.

Nucleotide Excision Repair

A DNA repair system in which a nuclease cuts out and replaces damaged stretches of DNA.

Telomeres

Special nucleotide sequences at the ends of eukaryotic chromosomal DNA molecules.

Telomerase

An enzyme that catalyzes the lengthening of telomeres in germ cells.

Chromatin

The complex of DNA and proteins that makes up eukaryotic chromosomes.

Euchromatin

Loosely packed chromatin that allows for gene expression.

Heterochromatin

Highly condensed chromatin, often found at centromeres and telomeres, where gene expression is suppressed.