TheIB Biology | Year 1 (Junior) · Proteins · part 3/7
Alpha Helix & Beta Sheet: Protein Structure
IB Biology B1.2, proteins: R-groups, primary structure and secondary structure, the alpha helix and the beta-pleated sheet (part 3 of 7, higher level). The chemical types of R-group, why the sequence of amino acids decides the shape, and how the alpha helix and the beta-pleated sheet are held by hydrogen bonds in the backbone.
In this lesson
- 0:00 Intro
- 0:24 Exam question
- 0:47 Warm-up
- 1:18 Types of R-group
- 2:16 Primary structure
- 3:10 Secondary structure
- 4:12 Explain: I do it
- 4:35 Explain: we do it
- 4:57 Explain: you do it
- 5:26 What earns the mark
- 5:58 Exam question solved
- 6:45 Recap
Answers to the practice questions at the end of the video
- Non-polar (hydrophobic), polar and charged.
- A carboxyl group in the R-group loses a hydrogen ion.
- Each R-group has its own chemical properties, so the sequence fixes which interactions form [1]; that is why the same sequence always folds in the same way [1].
Questions are original, in the style of the exam; marks are estimates.
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