Chapter 7: Control of Gene Expression

Gene control

The regulatory mechanisms that determine when, where, and to what extent genes are expressed or "turned on" in an organism.

Transcription factors

Proteins that can activate or repress gene expression by binding to specific DNA sequences known as regulatory elements.

Promoters

DNA sequences located near the start of a gene that provide binding sites for transcription factors and RNA polymerase, initiating transcription.

Enhancers

Regulatory elements that can be located far away from the gene they control and interact with promoters through DNA looping, enhancing transcription.

Silencers

Regulatory elements that repress gene expression by interacting with transcription factors or blocking the binding of activators.

Epigenetic modifications

Chemical modifications to DNA or histone proteins that can influence the accessibility of DNA to transcription factors and the transcriptional machinery.

DNA methylation

The addition of a methyl group to the DNA molecule, often resulting in gene silencing.

Histone modifications

Chemical modifications to histone proteins that can alter the structure of chromatin and either promote or inhibit gene expression.

Non-coding RNAs

RNA molecules that do not code for proteins but can regulate gene expression at the transcriptional or post-transcriptional level.

Alternative splicing

A process that allows the production of multiple protein isoforms from a single gene by selectively including or excluding specific exons during mRNA processing.

Post-translational modifications

Chemical modifications to proteins that can regulate their activity, localization, and stability.

Cell differentiation

The process by which unspecialized cells become specialized and acquire distinct structures and functions.

Transcription regulators

Proteins that control gene expression by switching genes on and off through binding to specific DNA sequences.

Signaling pathways

Intracellular pathways that transmit signals from the cell membrane to the nucleus, modulating gene expression and directing cell fate decisions.

Epigenetic modifications

Chemical modifications to DNA or histone proteins that contribute to the establishment and maintenance of cell identity.

Non-coding RNAs

RNA molecules that regulate gene expression at the transcriptional and post-transcriptional levels.

Cell-cell interactions

Communication between neighboring cells that contributes to the creation and maintenance of specialized cell types.

Enhancer RNAs

eRNAs are noncoding RNAs transcribed from enhancer regions of the genome.

Circular RNAs

circRNAs are covalently closed RNA molecules formed by back-splicing, where a downstream splice donor site joins with an upstream splice acceptor site.

Small interfering RNAs

siRNAs are incorporated into the RNA-induced silencing complex (RISC) and guide RISC to complementary mRNA sequences.

Piwi-interacting RNAs

piRNAs guide Piwi proteins to complementary sequences in TE transcripts, resulting in their degradation or transcriptional silencing.

Long noncoding RNAs

lncRNAs exhibit diverse mechanisms of action, including regulation of transcription, chromatin remodeling, and modulation of RNA processing.

MicroRNAs

They regulate gene expression by binding to complementary sequences in the 3' untranslated region (UTR) of target messenger RNAs (mRNAs).

Riboswitches

Riboswitches are structural elements present within mRNA molecules that can modulate gene expression in response to specific ligands.

RNA interference

RNAi is a post-transcriptional mechanism that regulates gene expression by using small RNA molecules.

Alternative splicing

Different combinations of exons within a pre-mRNA can be spliced together, generating multiple mRNA isoforms from a single gene.

RNA editing

The nucleotide sequence of mRNA can be modified by enzymatic processes, leading to changes in the coding sequence or regulatory regions.

Polyadenylation

The addition of a poly(A) tail to the 3' end of mRNA stabilizes the molecule, affecting its stability and translation efficiency.

mRNA capping

The addition of a 5' cap to mRNA protects it from degradation and facilitates translation initiation.

Mitotic stability

Mitotic stability ensures the faithful transmission of cell memory to daughter cells during cell division.

Chromatin remodeling

Chromatin remodeling complexes help reinforce cell memory by maintaining the accessibility and organization of chromatin.