Transcriptional Regulation & NF-κB Viral Hijacking Cytokine Storm

Flashcards covering transcriptional regulation, the lac and trp operons, cis and trans-acting elements, and alternative splicing based on the provided lecture notes.

Cytokines

Small proteins that tell immune cells what to do.

Cytokine Storm

A condition where cytokines stay too high, causing the immune system to go out of control, leading to tissue damage, leaky blood vessels, blood clots, organ failure, and possibly death.

Galactoside permease

A protein that brings lactose into the bacterial cell.

β-galactosidase

An enzyme that breaks lactose into glucose and galactose.

Operon

A group of genes controlled together by one promoter, found in prokaryotes.

Polycistronic mRNA

One long mRNA molecule that codes for several proteins, found only in prokaryotes.

Structural genes

Genes within an operon that make enzymes or proteins.

Regulatory genes

Genes that control the structural genes by turning them on or off.

Operator

A DNA segment in an operon that acts like a switch, controlling the interaction between the promoter and the genes.

Repressor

A protein that binds to the operator, blocking RNA polymerase and preventing gene transcription.

Negative control

A type of gene regulation where a protein (repressor) blocks transcription instead of starting it.

Allosteric Regulation (lac operon example)

When lactose binds to the repressor, it changes the repressor's shape, causing it to detach from the operator and allowing genes to turn ON.

De-repression

The process of lifting the block on transcription when a repressor detaches from the operator.

Glucose (in bacteria)

The preferred energy source for bacteria, which is always used first (constitutively expressed).

trp operon

An operon that makes enzymes responsible for synthesizing tryptophan.

End product repression

A regulatory mechanism where the final product of a metabolic pathway (e.g., tryptophan) tells the cell to stop making more when it is already present.

Cis-acting elements

DNA sequences located near the promoter where proteins can bind; they act as landing pads on the DNA itself.

Trans-acting elements

Genes that produce proteins (like repressors or activators) that can diffuse and act on DNA sequences located far away, potentially on different DNA molecules.

Trans-acting factors

Proteins made by trans-acting genes that float around and bind to cis-acting elements to control transcription.

Proximal control elements

Cis-acting DNA sequences located very close to the promoter (within ~100 base pairs) in eukaryotes, which fine-tune transcription.

Distal control elements

Cis-acting DNA sequences located far away from the promoter (>100 base pairs, sometimes thousands), which can influence transcription by DNA looping.

Enhancers

A type of distal control element that turns genes ON stronger.

Repressors (Distal control elements)

A type of distal control element that turns genes OFF.

Exons

Coding regions within a gene that are kept in the final mRNA molecule after splicing.

Introns

Non-coding regions within a gene that are removed during mRNA splicing.

Alternative splicing

A process that decides which exons are kept or skipped from a primary RNA transcript, leading to different protein variants from a single gene.

Cassette exons

An exon that is sometimes included and sometimes skipped during alternative splicing.

Mutually exclusive exons

A type of alternative splicing where only one of two specific exons is chosen for inclusion in the final mRNA.

Exon scrambling

A less common type of alternative splicing where exons are joined in a different order than their genomic sequence.

Alternative 5′ splice sites

A mechanism of alternative splicing where the starting point of intron removal changes.

Alternative 3′ splice sites

A mechanism of alternative splicing where the ending point of intron removal changes.

Retained introns

A type of alternative splicing where an intron is sometimes kept in the final mRNA, rather than being removed.