Epigenetics Flashcards

Flashcards on Epigenetics

Epigenetic Effects

Modification of a nucleic acid after it has been synthesized or by the perpetuation of protein structures, leading to heritable changes in gene expression without altering the DNA sequence.

Heterochromatin

Densely packed regions of chromatin, generally transcriptionally inactive.

Euchromatin

Loosely packed regions of chromatin, generally transcriptionally active.

Prion

A proteinaceous infectious agent that behaves as an inheritable trait, although it contains no nucleic acid.

Position Effect Variegation (PEV)

The phenomenon where the inactivation of a gene varies from cell to cell due to the variable length of heterochromatin spreading, resulting in different phenotypes.

Telomeric Silencing

The silencing of genes near telomeres due to the spreading of heterochromatin.

HP1

A key protein in forming mammalian heterochromatin, which binds to methylated histone H3 and promotes higher-order chromatin structures.

Rap1

Initiates heterochromatin formation in yeast by binding to specific DNA sequences.

Polycomb Group Proteins (Pc-G)

Proteins that perpetuate a state of repression through cell divisions.

Polycomb Response Element (PRE)

A DNA sequence required for the action of Pc-G proteins, serving as a nucleation center for heterochromatin formation.

Trithorax Group Proteins (TrxG)

Proteins that antagonize the actions of the Pc-G proteins, promoting gene activation.

DNA Methyltransferase

An enzyme that adds a methyl group to a specific target sequence in DNA.

Demethylase

An enzyme that removes a methyl group, typically from DNA, RNA, or protein.

De Novo Methyltransferase

An enzyme that adds a methyl group to an unmethylated target sequence on DNA.

Amyloid Fibers

Insoluble fibrous protein polymers with a cross β-sheet structure, generated by prions or other dysfunctional protein aggregations.

Dosage Compensation

Mechanisms employed to compensate for the discrepancy between the presence of two X chromosomes in one sex but only one X chromosome in the other sex.

Constitutive Heterochromatin

The inert state of permanently nonexpressed sequences, such as satellite DNA.

Facultative Heterochromatin

The inert state of sequences that also exist in active copies, such as one mammalian X chromosome in females.

X Inactivation Center (Xic)

A cis-acting region on the X chromosome that is necessary and sufficient to ensure that only one X chromosome remains active.

SMC (Structural Maintenance of Chromosome) Proteins

ATPases that include condensins and cohesins and are involved in chromosome structure maintenance.