Transcription & Gene Expression Vocabulary

Vocabulary flashcards covering key terms from the transcription and gene expression lecture.

Central Dogma

The directional flow of genetic information from DNA to RNA to protein.

Gene Expression

Process by which information in a gene is used to synthesize a functional product; varies by cell type and developmental stage.

Transcription

Nuclear synthesis of an RNA copy of a gene’s DNA sequence by RNA polymerase.

RNA Polymerase II

Eukaryotic enzyme that synthesizes mRNA and many non-coding RNAs; inhibited by α-amanitin.

RNA Polymerase I

Enzyme that transcribes large rRNAs (28S, 18S, 5.8S).

RNA Polymerase III

Enzyme that produces tRNAs, 5S rRNA, and other small RNAs.

Promoter

DNA sequence that determines the transcription start site and binds basal transcription machinery; not itself transcribed.

TATA Box

~25 bp upstream promoter element (TATAAA) recognized by TFIID (TBP) to initiate transcription.

CAAT Box

Distal promoter element (GGCCAATCT) that enhances transcription efficiency.

GC Box

Promoter element rich in guanine–cytosine pairs that binds SP1 and other factors.

Consensus Sequence

Short conserved DNA motif recognized by specific proteins such as transcription factors.

Transcription Factor (TF)

Protein that binds DNA to regulate transcription initiation, either activating or repressing.

Pre-initiation Complex

Assembly of RNA polymerase II with general TFs on the promoter before RNA synthesis begins.

Transcription Bubble

Local unwound region of DNA (~17 bp) where RNA polymerase reads the template strand.

Template (Antisense) Strand

DNA strand read 3′→5′ by RNA polymerase to build complementary RNA.

Coding (Sense) Strand

DNA strand with the same sequence as the RNA (except T→U) and not directly transcribed.

5′→3′ Directionality

Orientation in which RNA polymerase synthesizes RNA, adding nucleotides to the 3′-OH.

5′ Cap

Modified guanine (7-methylguanosine) added to the 5′ end of pre-mRNA for stability and ribosome binding.

7-Methylguanosine

Methylated guanine nucleotide forming the protective 5′ cap on eukaryotic mRNA.

Poly-A Tail

~200 adenine nucleotides added to the 3′ end of mRNA to enhance stability and export.

Polyadenylation Signal (AAUAAA)

RNA sequence that triggers cleavage and poly-A tail addition during termination.

Spliceosome

Large RNA-protein complex that removes introns and joins exons in pre-mRNA.

snRNP

Small nuclear ribonucleoprotein particle forming part of the spliceosome.

Exon

Coding sequence that remains in mature mRNA after splicing.

Intron

Non-coding sequence removed from pre-mRNA during splicing.

Alternative Splicing

Process by which different exon combinations generate multiple proteins from one gene.

Enhancer

Regulatory DNA element that increases transcription from a distance via activator proteins.

Silencer

DNA element that decreases transcription when bound by repressor proteins.

Epigenetic Control

Heritable modification of gene expression without DNA sequence change, e.g., histone acetylation or DNA methylation.

Histone Acetylation

Addition of acetyl groups to histone tails that loosens chromatin and activates transcription.

DNA Methylation

Addition of methyl groups to cytosine bases that generally represses transcription.

Alpha-amanitin

Mushroom toxin that specifically inhibits RNA polymerase II, halting mRNA synthesis.

Actinomycin D

Chemotherapeutic antibiotic that intercalates DNA and prevents RNA chain elongation by any RNA polymerase.

mRNA (Messenger RNA)

RNA that carries coding information from DNA to ribosomes for protein synthesis.

tRNA (Transfer RNA)

Adaptor RNA that brings specific amino acids to the ribosome during translation.

rRNA (Ribosomal RNA)

Structural and catalytic RNA component of ribosomes.

ncRNA (Non-coding RNA)

RNA molecules not translated into protein, including microRNA, snRNA, and others that regulate gene expression.

RNA Processing

Collective maturation steps—capping, splicing, and polyadenylation—that convert pre-mRNA into mature mRNA.