Chromatin Structure and Gene Regulation

These flashcards cover key concepts about chromatin structure and its role in gene regulation, essential for understanding cellular functions and molecular biology.

Chromatin

A complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells and plays a fundamental role in gene regulation.

Nucleosome

The basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wrapped around a core of histone proteins.

Euchromatin

A less compacted form of chromatin that is accessible for transcription and typically associated with active gene expression.

Heterochromatin

A highly compacted form of chromatin that is generally not accessible for transcription, often associated with gene silencing.

Histone Code

The hypothesis that specific patterns of histone modifications determine gene activity by providing binding sites for regulatory proteins.

Histone Acetylation

The addition of acetyl groups to histone proteins, which reduces the positive charge, leads to a more relaxed chromatin structure and promotes gene expression.

Chromatin Remodeling

The process by which the structure of chromatin is altered to either expose or obscure regions of DNA, affecting gene accessibility.

Histone Methylation

The addition of methyl groups to histone proteins, which can either activate or repress gene expression depending on the specific context.

DNA Compaction

The process of packaging DNA into a smaller volume to fit it within the nucleus, often through formation of chromatin and chromosomes.

Core Histones

The four main types of histone proteins (H2A, H2B, H3, and H4) that form the octameric core around which DNA is wrapped to form nucleosomes.

Histone Acetyltransferase (HAT)

An enzyme that adds acetyl groups to histones, often associated with gene activation.

Histone Deacetylase (HDAC)

An enzyme that removes acetyl groups from histones, usually associated with gene repression.

RNA Polymerase II

An enzyme that transcribes DNA into RNA, essential for gene expression in eukaryotic cells.

Transcription Factors

Proteins that bind to specific DNA sequences to regulate transcription of genetic information.

Centromere

The region of a chromosome that links sister chromatids and is essential for proper segregation during cell division.