What is a Protein? – a superb 7m video, the first 3m 25s covers protein structure:
Here Stephanie Castle covers amino-acids are linked together by condensation reactions and Dan Rott covers IB 2.4 – Proteins in 13m from Dan Rott:
Here’s a fantastic animated tutorial from McGraw Hill Education on Protein Structure.
Some past paper questions answered by IB Blueprint: Carbohydrates, lipids & proteins – Past Exam Paper 1 Questions; Carbohydrates, lipids & proteins – Paper 2 Questions.