IB›IB Biology HL›Mind mapsD1.2 Protein synthesisIB Biology HL: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsTranscriptionRNA polymerase copies the template strandA on DNA pairs with U in RNARNA grows 5' to 3'; template read 3' to 5'DNA sequence is unchanged by transcriptionPromoter binds transcription factors, then polymeraseProcessingIntrons removed; exons spliced together5' cap and polyA tail stabilise mRNAAlternative splicing: one gene, many polypeptidesNon-coding DNA: promoters, introns, telomeresTranslationmRNA binds the small subunitRibosome reads mRNA 5' to 3'Codon pairs with tRNA anticodonAmino acids joined by peptide bondsA site arrives, P site holds chain, E site exitsStarts at AUG, carrying methionineProtein synthesistranscription, translationAUGCGenetic codeTriplet code: 4³ = 64 codonsDegenerate: several codons per amino acidUniversal across organismsSickle cell: GAG → GUG, glutamic acid → valineAfter translationPre-proinsulin loses signal sequence in the RERC-peptide removed leaving A and B chainsProteasomes break down unwanted proteinsAmino acids are recycledExam tipsDo not swap template 3'→5' and RNA 5'→3'Arrive, Peptide, Exit for ribosome sitesRead mRNA triplets in a codon table