Regulation of Gene Expression Flashcards

Flashcards for reviewing key vocabulary and concepts related to gene expression regulation.

Gene Expression

The process by which information from a gene is used in the synthesis of a functional gene product (protein or RNA).

Operon Model

A cluster of functionally related genes can be coordinately controlled by a single on-off switch in bacteria.

Operator

A segment of DNA that serves as the 'on-off switch', usually positioned within the promoter.

Operon

The entire stretch of DNA that includes the operator, the promoter, and the genes they control.

Repressor

A protein that prevent gene transcription by binding to the operator and blocking RNA polymerase.

Corepressor

A molecule that cooperates with a repressor protein to switch an operon off.

Repressible Operon

An operon that is usually on, but binding of a repressor to the operator shuts off transcription.

Inducible Operon

An operon that is usually off, but a molecule called an inducer inactivates the repressor and turns on transcription.

Inducer

A molecule that inactivates the repressor to turn the lac operon on.

Inducible Enzymes

Enzymes of catabolic pathways whose synthesis is induced by a chemical signal.

Repressible Enzymes

Enzymes of anabolic pathways whose synthesis is repressed by high levels of the end product.

CAP (Catabolite Activator Protein)

Acts as an activator of transcription when glucose is scarce.

Differential Gene Expression

The expression of different genes by cells with the same genome, leading to differences between cell types.

Heterochromatin

Highly condensed chromatin that is usually not expressed.

Histone Acetylation

The attachment of acetyl groups to positively charged lysines in histone tails, generally loosening chromatin structure and promoting the initiation of transcription.

DNA Methylation

The addition of methyl groups to certain bases in DNA, usually cytosine, which can condense chromatin and lead to reduced transcription.

Epigenetic Inheritance

The inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence.

Control Elements

Segments of noncoding DNA that serve as binding sites for transcription factors that help regulate transcription.

Transcription Factors

Proteins that are essential for the transcription of all protein-coding genes and help regulate transcription.

Enhancers

Groupings of distal control elements, which may be far away from a gene or even located in an intron.

Activator

A protein that binds to an enhancer and stimulates transcription of a gene.

Mediator Proteins

Proteins that interact with activator proteins and proteins at the promoter to help assemble and position the initiation complex on the promoter.

Repressors (Transcription Factors)

Some transcription factors function as repressors, inhibiting expression of a particular gene by a variety of methods.

Alternative RNA Splicing

A process where different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns.

UTR (Untranslated Region)

Nucleotide sequences that influence the life span of mRNA in eukaryotes reside in the untranslated region at the 3′ end of the molecule.

Ubiquitin

Molecules attached to a particular protein to mark it for destruction.

Noncoding RNAs (ncRNAs)

RNAs that regulate gene expression at several points.

MicroRNAs (miRNAs)

Small single-stranded RNA molecules that can bind to complementary mRNA sequences and degrade the mRNA or block its translation.

Small Interfering RNAs (siRNAs)

Another class of small RNAs, similar to miRNAs but formed from different RNA precursors, that inhibit gene expression.

RNA Interference (RNAi)

The phenomenon of inhibition of gene expression by siRNAs .

Piwi-Associated RNAs (piRNAs)

A class of small ncRNAs that also induce formation of heterochromatin and block expression of transposons.

Nucleic Acid Hybridization

The base pairing of a strand of nucleic acid to its complementary sequence. Used to detect mRNA in a cell.

In Situ

In place, in the intact organism.

In Situ Hybridization

A technique that allows us to see the mRNA in place (in situ) in the intact organism

Reverse Transcriptase–Polymerase Chain Reaction (RT-PCR)

A widely used method for comparing the amounts of specific mRNAs in several different samples.

Complementary DNA (cDNA)

A DNA copy of an mRNA, synthesized by reverse transcriptase.

DNA Microarray Assays

Used in genome-wide expression studies. A microarray contains tiny amounts of many single- stranded DNA fragments affixed to the slide in a grid.

RNA Sequencing

Sequencing cDNA samples from different tissues or stages to discover which genes are expressed.