Transcriptional Regulation in Prokaryotes Flashcards

Flashcards for reviewing lecture notes on Transcriptional Regulation in Prokaryotes.

RNA Polymerase (RNAP)

The enzyme responsible for transcription.

Promoter sequences

DNA sequences that define where transcription of a gene by RNA polymerase begins.

Template Strand

The DNA strand that mRNA is built from; also called the antisense strand.

Coding Strand

Corresponds to the mRNA sequence (except Uracil replaces Thymine).

Cis-acting DNA elements

DNA elements required for transcription (e.g., promoter).

Trans-acting factors

Factors required for transcription (e.g., RNA polymerase and transcription factors).

RNA Polymerase holoenzyme

A multi-subunit complex in bacteria that binds to DNA and carries out transcription.

Core promoter

Formed by DNA elements found at the 5' end of a gene, close to the transcription start site in eukaryotes.

Upstream Regulatory elements

Regulatory sequences located upstream of the core promoter in eukaryotes.

RNA polymerase (Pol)

Enzyme in eukaryotes carrying out transcription along with other factors.

Operons

Genes organized in this way in bacterial genomes.

Activators

Stimulate RNA Polymerase binding.

Repressors

Prevent RNA Polymerase binding.

Ligands

Low-molecular-weight compounds that bind regulatory proteins, changing their conformation in response to environmental changes.

Repressors and Activators

Regulatory proteins.

Example of transcription regulation in prokaryotes

Lac Operon

Carbohydrates

The most abundant biomolecules on earth.

Monosaccharides

Simple sugars

Disaccharides

Formed by two monosaccharides bound together

LacY

E. coli integral membrane protein that imports (transports) lactose from the extracellular environment

Beta-galactosidase (called LacZ)

The enzyme that subsequently cleaves lactose into glucose and galactose is a

lac Operon

Contains the structural genes required for the metabolism of lactose.

lacI gene

Controls transcription of the lac operon

Inducer-Allolactose

Converts lac repressor into a form with low affinity for operator