Topic Review Guide: Gene Regulation

Reverse transcriptase

A DNA polymerase enzyme that catalyzes the process of reverse transcription.

TATA box

A TATA box is a DNA sequence that indicates where a genetic sequence can be read and decoded. It is a type of promoter sequence, which specifies to other molecules where transcription begins. The TATA box is named for its conserved DNA sequence, which is most commonly TATAAA.

Regulatory gene

A gene that is involved in the production of a substance that controls or regulates the expression of one or more genes, such as the gene that codes for a repressor protein that inhibits the activity of an operator gene.

repressor

A protein in which its binding to the operator inhibits the transcription of one or more genes. Supplement. Repressor proteins can be DNA- or RNA-binding: DNA-binding repressors - block the binding of RNA polymerase to the promoter. As a result, the gene is prevented from being transcribed into mRNA.

Alternative splicing

Alternative splicing, or differential 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.

Inducer

An agent capable of activating specific genes.A molecule that inhibits the action of the repressor of an operon, preventing it from freely binding with the operator gene and disabling its function.

Retrovirus

Any of a group of RNA viruses whose RNA is used as a template inside a host cell for the formation of DNA by means of the enzyme reverse transcriptase. The DNA thus formed is inserted into the host cell's genome.

retrovirus

Any of a group of RNA viruses whose RNA is used as a template inside a host cell for the formation of DNA by means of the enzyme reverse transcriptase. The DNA thus formed is inserted into the host cell's genome.

Regulatory protein

Any protein that influences the regions of a DNA molecule that are transcribed by RNA polymerase during the process of transcription. These proteins, which include transcription factors, therefore help control the synthesis of proteins in cells.

CREB

CREB (cAMP response element-binding protein) is a cellular transcription factor. It binds to certain DNA sequences called cAMP response elements (CRE), thereby increasing or decreasing the transcription of the downstream genes.

epigenetic control

Epigenetics literally means "above" or "on top of" genetics. It refers to external modifications to DNA that turn genes "on" or "off." These modifications do not change the DNA sequence, but instead, they affect how cells "read" genes.

histone acetylation

Histones are protein structures that are generally made up of basic, positively charged amino acids such as lysine and arginine. The property of histones allows them to bind to DNA molecules to neutralize the negative charge of DNA. histone acetylation is acetyl groups are added to amino acids of histone proteins

silencer

In genetics, a silencer is a DNA sequence capable of binding transcription regulation factors, called repressors. DNA contains genes and provides the template to produce messenger RNA (mRNA).

Stem cells

Stem cells are undifferentiated biological cells that can differentiate into specialized cells and can divide (through mitosis) to produce more stem cells. They are found in multicellular organisms.

Induction

The act or process of inducing or causing to occur, especially the production of a specific morphogenetic effect in the developing embryo through the influence of evocators or organisers or the production of anaesthesia or unconsciousness by use of appropriate agents.

Lac operon

The lac operon, short for lactose operon, is a series of three genes in bacteria that produce the necessary enzymes to obtain energy from lactose.

differentiation

The normal process by which a less specialized cell develops or matures to become more distinct in form and function

Negative control (repressible)

The regulator of the operon acts as a repressor that prevents transcription when it is active.

Positive control (inducible)

The regulator of the operon acts as an activator and is required in its active form for transcription.

Trp operon

The trp operon is an operon—a group of genes that is used, or transcribed, together—that codes for the components for production of tryptophan. The trp operon is present in many bacteria, but was first characterized in Escherichia coli.

activators

a DNA-binding transcription metabolite that positively modulates an allosteric Enzyme or regulates one or more genes by increasing the rate of transcription.

Transcription factors

a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence.

SRY gene

a sex-determining gene on the Y chromosome in mammals that determines maleness and is essential for development of the testes.

Promoter

a site on DNA to which the enzyme RNA polymerase can bind to initiate the transcription of DNA into RNA.

MicroRNA (miRNA)

a small non-coding RNA molecule (containing about 22 nucleotides) found in plants, animals and some viruses, that functions in RNA silencing and post-transcriptional regulation of gene expression.

Operon

a unit made up of linked genes that is thought to regulate other genes responsible for protein synthesis.

Enhancers

an enhancer is a short (50-1500 bp) region of DNA that can be bound by proteins (activators) to increase the likelihood that transcription of a particular gene will occur. These proteins are usually referred to as transcription factors. A DNA sequence that recognizes certain transcription factors that can stimulate transcription of nearby genes.

Operator

an operator is a segment of DNA to which a transcription factor binds to regulate gene expression by repressing it.

Tissue-specific proteins

are the products of genes expressed in at most two tissues and cell lines. Tissue-specific gene expression can result in the presence or absence of certain protein interactions and complexes, leading to profound functional differences of biological processes between the tissues.

Homeotic genes

homeotic genes are genes which regulate the development of anatomical structures in various organisms such as echinoderms, insects, mammals, and plants.

methylation

methylation is catalyzed by enzymes; such methylation can be involved in modification of heavy metals, regulation of gene expression, regulation of protein function, and RNA processing. DNA methylation is an epigenetic mechanism used by cells to control gene expression. A number of mechanisms exist to control gene expression in eukaryotes, but DNA methylation is a commonly used epigenetic signaling tool that can fix genes in the "off" position.