DNA & Chromosomes Vocabulary

Flashcards covering key vocabulary and definitions related to DNA, chromosomes, and gene expression, based on lecture notes.

DNA (Deoxyribonucleic Acid)

Carries genetic information; proteins help pack DNA into the nucleus and regulate gene expression.

Chromosome

Thread-like structure in the nucleus of eukaryotic cells that becomes visible before cell division; composed of DNA and protein.

Base Pairs

Pairs of nucleotides that form the rungs of the DNA ladder (A-T, C-G).

Telomere

Repeating sequence at the ends of DNA, important in DNA replication.

Centromere

Region of DNA where sister chromatids connect.

Chromatid

One of two identical strands of a replicated chromosome.

Nucleotide

Basic building block of DNA and RNA, consisting of a phosphate group, a 5-carbon sugar (ribose or deoxyribose), and a nitrogenous base.

Purine

Nitrogenous base with a two-ring structure (Adenine and Guanine).

Pyrimidine

Nitrogenous base with a one-ring structure (Cytosine, Uracil, and Thymine).

Phosphodiester bond

Covalent bond that links nucleotides in a DNA or RNA strand between the sugar and phosphate groups.

Antiparallel

The arrangement of DNA strands running in opposite directions (5' to 3' and 3' to 5').

Codon

A sequence of three nucleotides that codes for one amino acid.

Human Genome

All the DNA in a cell's nucleus.

Karyotype

Ordered display of all 46 human chromosomes.

Somatic Cell

Any biological cell forming the body of a multicellular organism other than gametes, germ cells, gametocytes or undifferentiated stem cells.

Gamete

Sex cell (sperm or egg) with 23 chromosomes in humans.

Autosome

Regular chromosome; not a sex chromosome.

Origin of Replication (Ori)

Where DNA replication begins.

P arm

The short arm of a chromosome.

Q arm

The long arm of a chromosome.

Sister Chromatids

Replicated chromosomes.

Gene

Segment of DNA that contains instructions for making one protein.

Silent Gene

A gene that is not being transcribed; 'off'.

Active Gene

A gene that is being transcribed; 'on'.

Constitutive Gene

A gene that is always turned 'on'.

Interphase Chromosome

Chromatin; DNA during interphase.

Mitotic Chromosome

Replicated chromosome during cell division.

Intron

Non-coding DNA segment.

Exon

Protein-coding DNA segment.

Chromatin

DNA plus proteins (histones).

Histone

Proteins around which DNA is wrapped (positive charge).

Nucleosome

A bead-like structure composed of DNA wrapped around histone proteins.

Euchromatin

Less condensed chromatin; genes are more accessible.

Heterochromatin

Highly condensed chromatin; DNA is not accessible.

Barr Body

Condensed X chromosome in female somatic cells that is not in use (X-inactivation).

Epigenome

How you control the DNA sequence; above the genome.

Epigenetic Marks

Chemical modifications to DNA or histones that alter gene expression without changing the DNA sequence.

DNA Methylation

Addition of a methyl group to DNA, typically repressing gene transcription.

Histone Modification

Modification of histone proteins, such as acetylation or methylation, affecting chromatin structure and gene expression.

MicroRNA (miRNA)

Small non-coding RNA molecules that regulate gene expression by binding to mRNA.

Epigenetics

The study of heritable changes in gene expression that do not involve alterations to the DNA sequence itself.

Epialleles

DNA sequences that have the same nucleotide sequence but differ in epigenetic marks; can result in different phenotypes.

Proteins that