D1.2 Protein synthesisIB Biology HL: Flashcards

Card 1 of 140 of 14 known

Question

Role of RNA polymerase?

Tap or press Space to reveal

Tap card or press Space to flip

See all 14 cards

Role of RNA polymerase?: Separates DNA strands and links RNA nucleotides complementary to the template.
Why is transcription a key control point?: It is the first stage of gene expression; genes are switched on or off here.
Codon vs anticodon?: Codon: three mRNA bases. Anticodon: complementary three tRNA bases.
Degeneracy and universality?: Several codons per amino acid; the same code in almost all organisms.
HL: Direction of RNA synthesis?: 5' to 3' (template read 3' to 5').
HL: What binds to the promoter to start transcription?: Transcription factors, allowing RNA polymerase to bind.
HL: Name four types of non-coding DNA.: Regulators (e.g. promoters), introns, telomeres, genes for rRNA and tRNA.
HL: What happens to introns and exons?: Introns are removed; exons are spliced together.
HL: Function of the 5' cap and 3' polyA tail?: Stabilise the mRNA (protect it from breakdown).
HL: What is alternative splicing?: Splicing different combinations of exons so one gene codes for several polypeptides.
HL: First step of translation initiation?: Small subunit binds to the 5' end of mRNA and moves to the start codon.
HL: Roles of the A, P and E sites?: A: incoming tRNA; P: tRNA with growing chain; E: empty tRNA exits.
HL: Two stages from pre-proinsulin to insulin?: Signal sequence removed (→ proinsulin); C-peptide region removed (→ insulin).
HL: Role of proteasomes?: Break down proteins so amino acids can be recycled; keeps the proteome functional.