Lesson 7: Control of Gene Expression I: Transcriptional Control Key Terms

transcriptional control

regulation by a cell of gene expression by controlling when and how often a given gene is transcribed

transcription regulator

general name for any protein that binds to a specific DNA sequence (known as a cis-regulatory sequence) to influence the transcription of a gene

cis-regulatory sequence

DNA sequences to which transcription regulators bind to control the rate of gene transcription. In nearly all cases, these sequences must be on the same chromosome (that is, in cis) to the genes they control

cooperative binding

a biochemical process where the binding of a molecule (a ligand) to one site on a macromolecule (like a protein) changes the affinity of remaining sites for subsequent molecules

transcriptional repressor

a protein that binds to specific regions of DNA or RNA to decrease or stop the transcription of a gene

transcriptional activator

specialized proteins that bind to specific DNA sequences to turn on or boost the rate of gene expression

gene control region

the set of linked DNA sequences regulating expression of a particular gene. Includes promoter and cis-regulatory sequences required to initiate transcription of the gene and control the rate of transcription

promoter

nucleotide sequence in DNA to which RNA polymerase binds to begin transcription

covalent histone modifcations

a chemical process that changes how tightly DNA is wrapped around histone proteins by adding or removing small molecular groups

transcriptional synergy

a process where multiple transcription factor proteins work together to increase the rate of gene transcription significantly more than the sum of their individual, separate effects

insulator

a specific DNA sequence that acts as a boundary element to control gene activity and organize chromosomes

RNA processing control

regulates mRNA splicing and processing to produce mature mRNA

RNA transport and localization control

controls which mRNAs leave the nucleus and where they are used in the cytoplasm

translational control

determines which mRNAs are translated and how much protein is produced

mRNA degradation control

selectively destroys mRNAs to limit protein production

leucine zipper

a common structural motif found in proteins, specifically in many transcription factors. It features a repeating pattern of the amino acid leucine every seventh position. This pattern forms an alpha helix that allows two protein strands to lock together like a zipper, helping them bind to DNA and control gene expression

histone replacement

the biological or experimental process where standard (canonical) histone proteins in chromatin are swapped out for specialized histone variants or mutant versions

nucleosome removal

the biological process where histone proteins are evicted or disassembled from DNA, exposing specific genetic sequences so cellular machinery can access them

tryptophan operon

a group of genes in bacteria like E. coli that work together to make the amino acid tryptophan (repressible)

zinc finger proteins

a large and diverse group of proteins that use small structural motifs coordinated by zinc ions to bind DNA, RNA, proteins, or other molecules. They make up one of the most abundant classes of regulatory proteins in eukaryotic genomes

Helix-Loop-Helix proteins

a family of basic helix–loop–helix transcription factors—specialized proteins that bind to DNA to control which genes are turned on or off

nucleosome remodeling

the energy-dependent process by which multi-protein complexes alter, move, or restructure nucleosomes to change how tightly DNA is packaged, making genetic material accessible or inaccessible to cellular machinery

Lac operon

a set of genes in bacteria like E. coli that works together to break down the sugar lactose (inducible)