RNA Synthesis and Regulation

These flashcards cover key terms and definitions related to RNA synthesis and regulation in prokaryotes and eukaryotes.

RNA polymerase

An enzyme that catalyzes the synthesis of RNA from a DNA template.

Template strand

The DNA strand that is transcribed into RNA, also known as the nonsense strand.

Coding strand

The DNA strand whose sequence corresponds to the RNA sequence, known as the sense strand.

Transcription bubble

A localized melting of the DNA that exposes the bases for transcription.

Promoter

A specific DNA sequence where RNA polymerase binds to initiate transcription.

Termination signal

A sequence that signals the end of transcription.

Sigma factor

A protein that enhances RNA polymerase's ability to initiate transcription at promoters in prokaryotes.

Facultative genes

Genes that are expressed only when their products are needed.

Operon

A cluster of genes transcribed as a single mRNA molecule controlled by a single promoter.

Repressor

A protein that binds to the operator region of an operon to inhibit transcription.

CAP (catabolite activator protein)

A protein that helps RNA polymerase bind to weak promoters when combined with cAMP.

Trans-acting factors

Proteins that bind to cis-acting elements to regulate gene expression.

Cis-acting elements

DNA sequences that regulate the transcription of nearby genes.

Alternative splicing

The process by which different combinations of exons are joined together to produce different mRNA variants from the same gene.

Spliceosome

A complex of proteins and snRNA that performs splicing of pre-mRNA.

Intron

Non-coding sequences removed from pre-mRNA during RNA processing.

Exon

Coding sequences that remain in the mRNA after splicing.

Capping

The addition of a modified guanine nucleotide to the 5' end of an mRNA transcript for stabilization.

Polyadenylation

The addition of a poly-A tail to the 3' end of an mRNA transcript to enhance its stability and translation.

Self-splicing introns

Introns that can catalyze their own removal from mRNA without the help of a spliceosome.

Rho factor

A protein involved in the termination of transcription through rho-dependent mechanisms.

Thermodynamic model of termination

Model explaining how the energy of base-pair formation contributes to the termination of transcription.