Molecular Biology: Chromosomes and DNA Structure

These flashcards cover essential vocabulary related to chromosome abnormalities, DNA structure, and replication processes, aiding in understanding the molecular foundations of genetics.

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during meiosis.

Aneuploidy

A condition resulting from the fertilization of gametes in which nondisjunction occurred, leading to an abnormal number of a particular chromosome.

Monosomic Zygote

A zygote having only one copy of a particular chromosome.

Trisomic Zygote

A zygote having three copies of a particular chromosome.

DNA (Deoxyribonucleic Acid)

The molecule that encodes hereditary information and directs the development of traits.

Transformation

A change in genotype and phenotype due to assimilation of foreign DNA.

DNA Polymerase

The enzyme that catalyzes the formation of DNA strands by adding nucleotides to an existing chain.

Primase

The enzyme that synthesizes a short RNA primer, allowing DNA polymerase to initiate DNA synthesis.

Helicase

An enzyme that unwinds the double helix of DNA at the replication forks.

Okazaki Fragments

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

Telomeres

Nucleotide sequences at the ends of eukaryotic chromosomes that protect against DNA loss during replication.

Euchromatin

Loosely packed chromatin that is accessible for transcription.

Heterochromatin

Tightly packed chromatin that is generally not transcribed.

Chargaff’s Rules

The principle stating that in any organism, the amount of adenine equals thymine, and the amount of guanine equals cytosine.

Semiconservative Replication

The process by which DNA replicates, producing two copies that each contain one original strand and one newly synthesized strand.

Nucleotide

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