Biology chapter 13: Gene Regulation

General transcription factor (GTF's)

5 different proteins that Olay a role in initiating transcription at the core promoter of structural genes in eukaryotes

Operator

A DNA sequence in bacteria that is recognized by activator or repressor proteins that regulate the level of gene expression

Mediator

A large protein complex that plays a role in initiating transcription at the core promoter of structural genes in eukaryotes

Regulatory transcription factor

A protein that binds to DNA in the vicinity of a promoter and affects the rate of transcription of one or more nearby genes

Silencer

A regulatory element in eukaryotes that prevents transcription of a given gene

Enhancer

A response element in eukaryotes that increases the rate of transcription

Activator

A transcription factor that binds to DNA and increases the rate of transcription

Repressor

A transcription factor that binds to DNA and inhibits transcription

Operon

An arrangement of two or more genes in bacteria that are under the transcriptional control of a single promoter

Polycystronic RNA

An mRNA that contains the coding sequences for two or more structural genes

Lac operon

An operon in the genome of E. coli that contains the genes for the enzymes that allow it to metabolize lactose

Trp Operon

An operon of E. coli that encodes enzymes required to make the amino acid tryptophan, a building block of cellular proteins

Constitutive gene

An unregulated gene that has constant levels of expression in all conditions over time

Initiation complex

Formed at the initiation of protein synthesis and includes initiation factors, tRNA, mRNA and the ribosomal subunit. initiation factors (IF) a group of proteins that are required for initiation of protein synthesis to occur.

Gene Expression

Gene function both at the level of traits and at the molecular level.

Histone modification

Histones are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes. They are the chief protein components of chromatin, acting as spools around which DNA winds, and playing a role in gene regulation. (s a covalent post-translational modification (PTM) to histone proteins which includes methylation, phosphorylation, acetylation, ubiquitylation, and sumoylation. The PTMs made to histones can impact gene expression by altering chromatin structure or recruiting histone modifiers)

Regulatory elements

In eukaryotes, a DNA sequence that is recognized by regulatory transcription factors and regulates the expression of genes

Regulatory sequence

In the regulation of transcription, a DNA sequence that as a binding site for genetic regulatory proteins. Regulatory sequences control whether a gene is turned on or off.

Repressible operon

In this type of operon, a small effector molecule inhibits transcription

Inducible operon

In this type of operon, the presence of a small effector molecule causes transcription to occur.

Constitutive genes

Not regulated, have constant level of expression. Proteins level don't change much even though environmental changes may cause this in regulated gene which would change.

TATA box

One of three features found in most eukaryotic promoters; the others are the transcriptional start site and regulatory elements

Core promoter

Referes to the TATA box and the transcriptional start site of a eukaryotic structural gene

Gene regulation

The ability of cells to control their level of gene expression

Proteome

The complete compliment or proteins that a cell organism can make

Genome

The complete genetic composition of a cell or a species

Differential gene regulation

The phenomenon in which the expression of genes differs under various environmental conditions in specialized cell types.

Combinatorial control

The phenomenon whereby a combination of many factors determines the expression of any given gene

Cell differentiation

The process by which different cells within a developing organism acquire specialized forms and functions due to the expression of cell-specific genes

Transcriptional start site

The site in a eukaryotic promoter where transcription begins

Postitive control

Transcriptional regulation by activator proteins

Negative control

Transcriptional regulation by repressor proteins

Small effector molecule

With regard to transcription, refers to a molecule that exerts its effects by binding to a regulatory transcription factor, causing a conformational change in the protein

Methylation

a process by which methyl groups are added to the DNA molecule. Methylation can change the activity of a DNA segment without changing the sequence. When located in a gene promoter, DNA methylation typically acts to repress gene transcription.

Alternative splicing

is a regulated process during gene expression that results in a single gene coding for multiple proteins. In this process, particular exons of a gene may be included within or excluded from the final, processed messenger RNA (mRNA) produced from that gene.