Biology · Continuity and change

D1.2 — Protein synthesis

Biology · SL / HL · syllabus-mapped notes

1. D1.2.1

   Transcription as the synthesis of RNA using a DNA template

   Explain transcription and the roles of RNA polymerase.

2. D1.2.2

   Role of hydrogen bonding and complementary base pairing in transcription

   Explain complementary base pairing in transcription, distinguishing sense from template strand.

3. D1.2.3

   Stability of DNA templates

   Explain why DNA templates must remain stable through repeated transcription.

4. D1.2.4

   Transcription as a process required for the expression of genes

   Explain gene expression, and why transcription is the key stage for switching genes on or off.

5. D1.2.5

   Translation as the synthesis of polypeptides from mRNA

   Explain translation, and why it is named as it is.

6. D1.2.6

   Roles of mRNA, ribosomes and tRNA in translation

   State the roles of mRNA, tRNA and ribosomes in translation.

7. D1.2.7

   Complementary base pairing between tRNA and mRNA

   Explain how anticodon-codon pairing puts the right amino acid in the right place.

8. D1.2.8

   Features of the genetic code

   Explain why the code is a triplet code, and what degeneracy and universality mean.

9. D1.2.9

   Using the genetic code expressed as a table of mRNA codons

   Read the codon table to deduce amino acid sequences and the DNA that coded for them.

10. D1.2.10

    Stepwise movement of the ribosome along mRNA and linkage of amino acids by peptide bonding to the growing polypeptide chain

    Explain the translation cycle through the A, P and E sites.

11. D1.2.11

    Mutations that change protein structure

    Explain how a base substitution changes protein structure, using sickle cell disease.

12. D1.2.12

    Directionality of transcription and translation

    Explain why both transcription and translation run 5' to 3'.

13. D1.2.13

    Initiation of transcription at the promoter

    Explain how promoters, activators and repressors initiate or block transcription.

14. D1.2.14

    Non-coding sequences in DNA do not code for polypeptides

    Give five examples of non-coding sequences and their functions.

15. D1.2.15

    Post-transcriptional modification in eukaryotic cells

    Explain 5' capping, poly-A tails and the splicing of introns from exons.

16. D1.2.16

    Alternative splicing of exons to produce variants of a protein from a single gene

    Explain alternative splicing, and why it increases the diversity of the proteome.

17. D1.2.17

    Initiation of translation

    Explain the special steps that initiate translation.

18. D1.2.18

    Modification of polypeptides into their functional state

    Explain the modifications that turn a polypeptide into a functional protein.

19. D1.2.19

    Recycling of amino acids by proteasomes

    Explain how proteasomes destroy tagged proteins and recycle amino acids.