Eukaryotic Gene Regulation Flashcards

Flashcards for reviewing Eukaryotic Gene Regulation

Methods of Gene Regulation in Eukaryotes

A. Transcriptional control, B. Control of mRNA processing, C. Posttranscriptional control, D. Control of the epigenome, E. The Genetic Hierarchy

Organization of a Eukaryotic Gene

Each gene is accompanied by its own promoter and other control elements; Transcription factors bind to control elements to activate/deactivate the gene

Transcriptional Control

Control the formation of the transcription-initiation complex; Many proteins (transcription factors) have to link up in order for RNA polymerase to attach to the promoter; Transcription will not occur if even a single piece is missing

Enhancers

The most distant transcription factors; DNA has to fold in order for the enhancers to reach the complex

Altering Control Elements

Mutations in control element sequences; Binding of control elements with toxic chemicals

mRNA Modification

mRNAs are modified after transcription is complete; Cells can control which proteins are made by controlling the splicing of the mRNA

Non-coding RNAs (ncRNA)

RNAs produced from information in the genes that are NOT translated into proteins; Have 3D shapes and many different functions; Many help regulate gene expression and protein activity

ncRNAs Can Block Translation

MicroRNAs (miRNA) and small interfering RNAs (siRNA) can block translation; If complementary to mRNA transcript, it will not be translated; If siRNAs, this = RNA Interference (RNAi)

Posttranslational Control

Unneeded proteins can be marked for destruction by ubiquitin; Proteosomes – Giant protein complexes that bind protein molecules and degrades them

Epigenetic Control

Controls an enzymes access to the DNA by controlling how tightly the DNA is wrapped; Chromatin – DNA coiled around histone proteins; Nucleosome – A loop of DNA wrapped around a small group of histone proteins

Modifications to Nucleosomes

Loosening = increases transcription; Tightening = decreases transcription; Actions that loosen DNA – Acetylation, methylation WITH simultaneous phosphorylation; Actions that tighten DNA – Deacetylation, methylation

Master genes

Activate other genes when turned on; By turning on one gene, many others can be recruited simultaneously

Homeotic genes

Master genes used during embryonic development; Small changes (mutations) to Hox genes can drastically affect how a body is built

SRY Gene

The human Y chromosome carries the SRY gene; An early human embryo appears neither male nor female; SRY expression in XY embryos triggers formation of testes (male gonads) that secrete testosterone, which initiates development of other male traits