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IB Biology | Year 1 (Junior) · Proteins · part 5/7

How Insulin Is Made (Polypeptide Modification)

How Insulin Is Made (Polypeptide Modification)

IB Biology B1.2, proteins: how insulin is made, the modification of polypeptides and proteasomes (part 5 of 7, higher level). How a new polypeptide is modified before it can work, how pre-proinsulin becomes insulin in two stages, and how proteasomes recycle amino acids. Ends with the two guiding questions of the topic.

In this lesson

  1. 0:00 Intro
  2. 0:24 Exam question
  3. 0:49 Warm-up
  4. 1:20 Modification of polypeptides
  5. 2:00 Insulin in two stages
  6. 3:15 Proteasomes
  7. 4:19 Explain: I do it
  8. 4:43 Explain: we do it
  9. 5:03 Explain: you do it
  10. 5:29 What earns the mark
  11. 6:02 Exam question solved
  12. 6:42 The two guiding questions
  13. 7:46 Exit questions
Answers to the practice questions at the end of the video
  1. Proinsulin.
  2. All the proteins that a cell (or tissue, or organism) produces at a given time.
  3. The sequence fixes which R-groups are present and in what order, and so how the chain folds [1]; folding and disulfide bonds give insulin a precise three-dimensional shape [1]; that shape fits its receptor, which lets it act as a hormone [1].

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

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