Protein Synthesis — transcription → translation
VCE Biology · DNA, genes and protein synthesis · 9 flashcards, free to study.
Every step from DNA → mRNA → protein. Includes the splicing detail VCAA loves.
- Direction DNA is read during transcription
- 3' → 5' on the template strand (mRNA built 5' → 3').
- What does RNA polymerase do?
- Binds the promoter, unwinds DNA, synthesises mRNA from the template strand.
- Splicing — what happens?
- Introns are removed and exons joined; carried out by the spliceosome.
- Codon vs anticodon
- Codon: 3 mRNA bases coding for an amino acid. Anticodon: complementary tRNA triplet that binds it.
- Start codon
- AUG — codes for methionine.
- Stop codons
- UAA, UAG, UGA — no amino acid; release factor ends translation.
- Why is the genetic code described as 'degenerate'?
- Multiple codons can encode the same amino acid (e.g. 6 different codons for leucine).
- Three stages of translation
- Initiation (ribosome assembly), elongation (peptide bond formation), termination (stop codon → release).
- Post-translational modifications — example
- Folding into 3D shape, addition of carbohydrate groups (glycosylation), cleavage of signal peptides.