33: Gene Expression Regulation in Eukaryotes

Differential gene expression

Forms specialized cell types, expression of different gene sets in cells with the same genome.

Chromatin

DNA + proteins, specifically histones.

Chromatin remodeling

Chromatin structure changed to allow/inhibit transcription.

Post-Translational modifications

Modification of polypeptide after its production by translation.

Histones

Basic proteins that combine with DNA.

Nucleosomes

Unit of chromatin, consisting of a group of 8 histones with 200 nucleotides, 10 nm.

Chromosome territory

Region within interphase eukaryote occupied by a certain chromosome.

DNA methyltransferases

Enzymes that add a methyl group to DNA.

DNA methylation

Addition of -CH3 to a molecule.

Histone code

How chemical changes to histone proteins can control how genes are turned on or off in cells.

Histone acetyltransferases

Enzymes that loosen chromatin structure by adding acetyl groups to histone proteins (HATs).

Histone deacetylases

Enzymes that remove acetyl groups, leading to condensation of chromatin.

Acetylation

Addition of (-COCH3) to a molecule.

Chromatin remodeling complex

Proteins that change the shape of chromatin to control how easily the DNA can be read and used by the cell.

Epigenetic inheritance

Inheritance mechanism not due to differences in nucleotide sequence of genes.

Core promoter

Binds general transcription factors to enable RNA polymerase to begin transcription.

TATA box

Landing pad for the machinery that starts copying the gene into RNA.

Regulatory sequences

DNA/RNA segments involved in controlling gene expression.

Promoter proximal elements

Regulatory sequences close to the promoter (in yeast).

Enhancers

Regulatory sequences located downstream/upstream of the start site of transcription.

Transcriptional activators

Proteins that bind to enhancers to initiate transcription.

Silencers

Repressor proteins that bind to inhibit transcription.

General transcriptional factors

Proteins that assemble on the promoter and aid RNA polymerase.

TATA binding protein (TBP)

Binds to the core promoter with or without a TATA box.

Mediator

Bridge between regulatory transcription factors, general transcription factors, and RNA polymerase II.

Pioneer transcription factor

Recruits proteins that decondense chromatin.

Pre-initiation complex

Proteins assembled around the promoter when transcription begins.

Alternative splicing

Maturation of mRNA involving intron/exon removal.

RNAi

mRNA degradation that inhibits translation.

microRNA (miRNA)

Forms RISC (RNA-induced silencing complex).

Proteasome

Destroys proteins marked with ubiquitin addition.

Tumor suppressors

Proteins/genes that prevent cell division under unstable conditions.

Protooncogens

First cancer genes that stimulate cell division.

Oncogene

Mutant allele that promotes cancers.

P53 tumor suppressor

Stops damaged cells from growing and dividing, leading to self-destruction.