Control of Gene Expression

Gene

A section of DNA that contains instructions for making a functional product, such as a protein or RNA

Coding region

The part of a gene that contains the information used to determine a protein’s amino acid sequence

Promoter

A region of DNA where RNA polymerase and other proteins bind to begin transcription

RNA polymerase

An enzyme that reads DNA and makes an RNA copy during transcription

Transcription factors

Proteins that help control whether a gene is transcribed (coped into RNA)

General transcription factors

Proteins needed to help RNA polymerase begin transcription of most protein-coding genes in eukaryotes

Specific transcription factors

Proteins that increase or decrease transcription of particular genes

DNA binding motifs

Special shapes or structures in proteins that allow them to attach to specific DNA sequences

Initiation complex

A group of proteins, including RNA polymerase, assembled at a promoter to begin transcription

Transcription complex

A group of proteins working together to carry out transcription

Activator

A protein that increases gene expression by helping transcription occur

Repressor

A protein that decreases or blocks transcription of a gene

Positive control

Gene regulation where an activator helps turn on or increase transcription

Negative control

Gene regulation where a repressor reduces or prevents transcription

Induction

Turning on or increasing expression of a gene, often in a response to signal

Repression

Turning off or decreasing expression of a gene

Enhancers

DNA sequences where activator proteins bind to increase transcription of a gene

Transcriptional gene regulation

Controlling how much RNA is made from a gene by increasing or decreasing transcription

Operon

A group of bacterial genes controlled by the same promoter and transcribed together

Operator

A DNA sequence where a repressor can bind to control transcription of an operon

Lac operon

A group of bacterial genes that helps break down lactose. It is strongly expressed when lactose is available and glucose is low

Trp operon

A group of bacterial genes used to make tryptophan. Usually turned off when enough tryptophan is available

cAMP

A small signaling molecule that helps bacteria respond to low glucose levels and can increase transcription of the lac operon

Primary transcript

The first RNA copy made from DNA before it is fully processed into mature RNA

RNA splicing

Removing introns (noncoding sections) from RNA and joining exons together

Exons

Sections of RNA that remain in the mature RNA after splicing

Spliceosomes

Groups of RNA and proteins that remove introns and join exons during RNA splicing

Alternate splicing

Joining exons in different combinations so one gene can produce different versions of a protein

mRNA editing

Changing the nucleotide sequence of an RNA molecule after transcription

UTR (Untranslated Region)

A section of mRNA that is not translated into protein but can help control how the mRNA is used or how long it lasts

Export inhibition

Preventing an RNA molecule from leaving the nucleus, which can stop it from being translated into a protein

Post-transcriptional gene regulation

Controlling gene expression after RNA has been made, such as through splicing, RNA breakdown, or blocking translation

Double-stranded RNA

An RNA molecule made of two complementary strands paired together

Small RNAs

Short RNA molecules that help regulate gene expression, often by preventing certain mRNAs from making proteins

RNA interference (RNAi)

A process where small RNAs help silence genes by breaking down mRNA or preventing its translation

siRNA (small interfering RNA)

A short RNA that guides proteins to a closely matching mRNA, usually causing that mRNA to be destroyed

miRNA (microRNA)

A small RNA that binds to target mRNAs and usually reduces protein production by blocking translation or promoting mRNA breakdown

Chemical modification of proteins

Adding or removing chemical groups from proteins to change their activity, location, or function

Post-translational gene regulation

Controlling a protein’s activity, stability, or breakdown after it has been made

Ubiquitin

A small protein that can be attached to other proteins, often to mark them for destruction

Ubiquitination

The process of attaching ubiquitin to a protein, often signaling that it should be broken down

Proteasome

A protein complex that breaks down proteins that have been marked for destruction