Gene Expression Flashcards

Flashcards generated from General Biology II lecture notes on Gene Expression by C. von Roretz.

Euchromatin

Loosely packed DNA, generally expressed.

Heterochromatin

Tightly packed DNA, generally not expressed.

Acetylation of Histones

Adding acetyl groups (COCH3) to lysines on histones, which reduces the attraction between DNA and histones, promoting loose chromatin structure and permitting transcription.

HATs (Histone Acetyl Transferases)

Enzymes that add acetyl groups to histones.

HDACs (Histone Deacetylases)

Enzymes that remove acetyl groups from histones.

Histone Methylation

Promotes association of histones and tighter packing of DNA.

Histone Phosphorylation

Loosens the association of histones with DNA.

DNA Methylation

Reduces transcription and can be used for long-term gene silencing.

Epigenetics

Heritable gene expression that is not encoded in the nucleotide sequence itself, but rather through histone and DNA modifications.

Transcription

The process of copying a specific gene into a short-term version (mRNA).

Promoter Region

A region of DNA where transcription factors associate, containing the TATA box.

Activators

Enhance transcription by binding to distal control elements.

Repressors

Inhibit transcription by binding to proximal control elements.

Control Elements

Regions of DNA that can recruit transcription factors, either close to the promoter (proximal) or far away (distal).

Enhancers

Another name for a distal control element; sequences of DNA that primarily recruit activators of transcription.

Activators

Transcription factors that bind to distal or proximal control elements to help/support transcription.

Repressors

Transcription factors that only bind proximal control elements and inhibit transcription.

Operator Sequence

A sequence located in DNA near the promoter where a repressor can bind to prevent transcription.

Repressible Operon (Trp Operon)

Default is to GO! and Trp allows repression.

Inducible Operon (Lac Operon)

Default is NO! and Lac now allows transcription.

Capping

Protection and export of mRNA

Polyadenylation

Protection and export of mRNA

Splicing

Generating diversity and export

5’ mRNA Cap

Inverted GTP at the 5’ end of the mRNA, protecting it in the cytoplasm and involved in splicing initiation, export, and translation initiation.

PolyA Tail

50 to 250+ adenines at the 3’ end of mRNA, involved in export, protection from degradation, and translation.

Introns

Excess material in premature mRNAs; intragenic regions.

Splicing

The removal of introns from premature mRNAs.

miRNA (microRNA)

Small (~22nt) RNA fragments that bind to mRNA, leading to translational repression or degradation.

Proteasome

A protein with many ubiquitins is taken into the _ for degradation.

Viruses

Obligate intracellular parasites that must produce both protein and genetic material before leaving the host cell.

Lytic

The term for when a cell dies immediately because of a virus.

Lysogenic

The term for when a cell stores a virus and divides.

Silent Mutation

Mutation where the codon gives the same amino acid

Missense Mutation

Mutation where the codon gives a different amino acid

Nonsense Mutation

Mutation where the codon is now a STOP codon

Frameshift Mutations

Mutations that skew the coding of a gene (altered reading frame).