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IB Biology Topic D1.2 Protein Synthesis Revision… | RevisionDojo

A1.1 Water

A1.2 Nucleic acids

A2.1 Origins of cells (HL)

A2.2 Cell structure

A2.3 Viruses (HL)

A3.1 Diversity of organisms

A3.2 Classification and cladistics (HL)

A4.1 Evolution and speciation

A4.2 Conservation of biodiversity

B1.1 Carbohydrates and lipids

B1.2 Proteins

B2.1 Membranes and membrane transport

B2.2 Organelles and compartmentalization

B2.3 Cell specialization

B3.1 Gas exchange

B3.2 Transport

B3.3 Muscle and motility (HL)

B4.1 Adaptation to environment

B4.2 Ecological niches

C1.1 Enzymes and metabolism

C1.2 Cell respiration

C1.3 Photosynthesis

C2.1 Chemical signalling (HL)

C2.2 Neural signalling

C3.1 Integration of body systems

C3.2 Defense against disease

C4.1 Populations and communities

C4.2 Transfer of energy and matter

D1.1 DNA replication

D1.2 Protein synthesis

D1.3 Mutations and gene editing

D2.1 Cell and nuclear division

D2.2 Gene expression (HL)

D2.3 Water potential

D3.1 Reproduction

D3.2 Inheritance

D3.3 Homeostasis

D4.1 Natural selection

D4.2 Sustainability and change

D4.3 Climate change

IB
D1.2 Protein synthesis

D1.2G Translation initiation, polypeptide modification and recycling (HL)

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Subtopics and learning objectives

D1.2.17 Initiation of translation (HL)

D1.2F Non-coding DNA, post-transcriptional modification and alternative splicing (HL)

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Translation initiation positions the ribosome on the start codon so the very first amino acid is read correctly

Initiation is the first stage of translation, in which the ribosome assembles on the mRNA at the correct starting point.
The players are the same as in the rest of translation: the mRNA template, the two ribosomal subunits, and the initiator tRNA carrying methionine.

The small subunit binds the mRNA, scans to the start codon, and the initiator tRNA reads AUG in the P site

The small ribosomal subunit binds the 5′ end of the mRNA.
1. In eukaryotes the small subunit recognises the 5′ cap that marks this end of the mRNA.

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D1.2.17 Initiation of translation (HL)
D1.2.18 Modification of polypeptides into their functional state (HL)
D1.2.19 Recycling of amino acids by proteasomes (HL)