Molecular Organization of Chromosomes and Genomes

Flashcards covering key concepts related to molecular organization of chromosomes and genomes.

Genome size

Varies between viruses, prokaryotes, and eukaryotes; parasites typically have smaller genomes.

C-value paradox

Genome size does not correlate with gene number or complexity.

Supercoiling of DNA

Extra twisting of DNA that helps pack DNA into bacterial cells, can be positive or negative.

Topoisomerases

Enzymes that relieve twisting by cutting and rejoining DNA strands; includes Topoisomerase I and II.

Nucleosome

A structural unit of eukaryotic chromosomes, consisting of DNA wrapped around histone proteins.

Acetylation of histones

Modification that favors transcription by loosening chromatin structure.

Chromatin condensation

The process by which chromatin is compacted during cell division.

Transposable Elements

Segments of DNA that can move within the genome, including cut-and-paste elements and retrotransposons.

Mutagens

Agents that increase the mutation rate above the spontaneous background rate.

Mismatch repair

The process of correcting errors that occur during DNA replication.

Telomerase

An enzyme that adds DNA repeats to the ends of chromosomes to prevent degradation.

Epigenetics

Changes in gene expression that do not involve alterations to the DNA sequence, often involving DNA methylation.

Alternate splicing

A process that allows a single gene to produce multiple protein isoforms by splicing RNA transcripts in different ways.

Dideoxy sequencing

A method of DNA sequencing that uses chain-terminating nucleotides to generate DNA fragments of varying lengths.

RNA polymerase

The enzyme that synthesizes RNA from a DNA template during transcription.

Gene silencing by siRNA

A mechanism where small interfering RNA degrades a specific target RNA molecule.