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IB Biology | Year 1 (Junior) · Proteins · part 2/7

Protein Denaturation: Heat & pH Explained

Protein Denaturation: Heat & pH Explained

IB Biology B1.2, proteins: essential amino acids, the variety of polypeptides and denaturation (part 2 of 7, for SL and HL). Why essential amino acids must come from food, why the number of possible polypeptides is enormous, and how heat and pH denature a protein.

In this lesson

  1. 0:00 Intro
  2. 0:23 Exam question
  3. 0:42 Warm-up
  4. 1:16 Essential amino acids
  5. 2:02 Variety of polypeptides
  6. 2:47 Shape and denaturation
  7. 4:07 Explain: I do it
  8. 4:26 Explain: we do it
  9. 4:44 Explain: you do it
  10. 5:10 What earns the mark
  11. 5:45 Exam question solved
  12. 6:27 Recap
Answers to the practice questions at the end of the video
  1. 20⁴ = 160 000.
  2. High temperature and a change in pH.
  3. The higher pH changes the charges on the R-groups [1]; bonds between R-groups break and the shape changes, so pepsin is denatured [1]; the active site no longer fits the substrate [1].

Questions are original, in the style of the exam; marks are estimates.

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