Gene Transcription and RNA Modification

Gene

Segment of DNA for functional product RNA or polypeptide

Transcription

Process of copying DNA into RNA without altering DNA structure

Gene Expression

Utilizes gene information to produce functional products like proteins

Structural Genes

Encode amino acid sequence of a polypeptide

Messenger RNA (mRNA)

Product of transcription determining amino acid sequence in translation

Regulatory Sequence

DNA segment influencing transcription rate via regulatory proteins

Promoter

Initiates transcription by binding RNA polymerase

Terminator

Signals end of transcription

Ribosome Binding Site

Location where ribosome binds mRNA to start translation

Start Codon

Specifies first amino acid in polypeptide sequence

Codons

Three nucleotide sequences in mRNA specifying amino acids

Stop Codon

Specifies end of polypeptide synthesis

Template Strand

DNA strand transcribed to create complementary RNA transcript

Non-Template Strand

Opposite DNA strand not transcribed

Substitution

Replacing thymine in DNA with uracil in RNA

Transcription Factors

Recognize promoter and regulatory sequences to control transcription

Translation

Process of synthesizing proteins from mRNA

RNA Polymerase

Enzyme catalyzing RNA synthesis during transcription

Holoenzyme

Complete RNA polymerase enzyme with sigma factor

Elongation

Stage of transcription where RNA polymerase synthesizes RNA

Termination

End of transcription process causing dissociation of RNA polymerase

Promoters

DNA sequences directing transcription initiation

Consensus Sequence

Most common bases in a specific type of DNA sequence

Sigma Factor

Part of RNA polymerase recognizing promoter regions

RNA polymerase

Enzyme that unwinds DNA and synthesizes RNA

Proofreading

Function of RNA polymerase to correct errors

Open complex

Structure formed by RNA polymerase during transcription

RNA-DNA hybrid

Hybrid structure formed during transcription

Eukaryotic RNA polymerases

Three enzymes transcribing nuclear DNA

Core promoter

Sequence including TATA box and start site

Regulatory elements

DNA sequences affecting RNA polymerase binding

Enhancers

DNA sequences stimulating transcription

Silencers

DNA sequences inhibiting transcription

Cis-acting elements

DNA sequences affecting a specific gene

Trans-acting elements

Proteins binding to DNA sequences

Basal transcription

Low-level transcription at core promoter

General transcription factors

Proteins required for transcription initiation

Mediator

Complex mediating regulatory effects on transcription

Spliceosome

Complex for pre-mRNA splicing in eukaryotes

Exons

Coding sequences in pre-mRNA

Introns

Intervening sequences in pre-mRNA

RNA splicing

Process of removing introns and connecting exons

Alternative splicing

Allows different polypeptides from the same gene

Capping

Addition of 7-methylguanosine cap to mRNA

Polyadenylation

Addition of polyA tail to mRNA 3' end