ap bio unit 6

Central Dogma

DNA stores information, RNA carries it, and proteins carry out functions.

Gene expression

The process of using information in DNA to make a protein.

Gene

A segment of DNA that codes for a protein.

Transcription

The process of making mRNA from a DNA template.

RNA polymerase

The enzyme that reads DNA and builds mRNA.

Promoter

A DNA sequence where RNA polymerase binds to start transcription.

Template strand

The DNA strand that is read to make mRNA.

mRNA

A copy of a gene that carries instructions to the ribosome.

RNA processing

Changes made to mRNA before it leaves the nucleus.

Intron

A noncoding section of RNA that is removed.

Exon

A coding section of RNA that is kept.

Alternative splicing

One gene produces different mRNAs by keeping different exons.

5′ cap and poly-A tail

Structures added to mRNA to protect it and help with translation.

Translation

The process of building a protein from mRNA.

tRNA

RNA that carries amino acids to the ribosome.

Codon

A three-base sequence on mRNA that codes for an amino acid.

Anticodon

A three-base sequence on tRNA that matches a codon.

Gene regulation

Control of when and how much a gene is expressed.

Mutation

A change in the DNA sequence.

Frameshift mutation

A mutation that shifts the reading frame and changes many amino acids.

operon

a group of genes under coordinated control

lac operon

inducible operon: active repressor binds to the operator, inducer (lactose) binds to and inactivates the repressor

trp operon

repressible operon: repressor is initially inactive, corepressor (tryptophan) binds to the repressor and makes it active

promoter

sequence where RNA polymerase binds

repressor

DNA or RNA-binding protein that inhibits the expression of one or more genes by binding to the operator or associated silencers

inducible operon

lactose binds to and inactivates the repressor

repressible operon

corepressor binds to the repressor and makes it active