Introduction

Lipids and proteins are both formed by condensation reactions similar to carbohydrates, but while ester and glycosidic bonds both form by combining two adjacent OH groups, peptide bonds in proteins form by combining the H from the amine end of one amino acid, and the OH from the acid end of another.

While questions about carbohydrates often focus on the condensation reactions, though, questions about lipids are often concentrated on the differences between saturated and unsaturated fatty acids, and questions about proteins usually focus on the tertiary structure and the bonds that make their shapes so specific.

Reading

Edexcel AS/A Level Biology Student Book 1 pages 14 to 21, page 25

Read and Make Notes

Read pages 14 to 15, making appropriate notes and completing the ‘in-text’ questions.

Consolidate

Now consolidate your understanding by working through these additional resources:

READ – Lipids Factsheet 1

READ – Lipids Factsheet 2

REVIEW – Lipids Concept Map

EXPLORE – Lipids Topic (Khan Academy)

WATCH – Triglyceride Formation (Nutrition)

Read and Make Notes

Read pages 16 to 21, making appropriate notes and completing the ‘in-text’ questions.

Consolidate

Now consolidate your understanding by working through these additional resources:

EXPLORE – Proteins Topics (Khan Academy)

COMPLETE – Protein Structure Worksheet

CHECK – Protein Structure Worksheet – Answers

REVIEW – The Structure of Proteins (PowerPoint)

READ – Proteins Poster

REVIEW – Proteins Factsheet

REVIEW – Biuret Test (Online Biology Notes)

Make Notes Icon.png Tasks

Complete the following:

Complete questions 5 and 6 on page 25.

Top Tips

Make sure that you understand the following key points:

The difference between saturated and unsaturated fatty acids and what that means for their properties.
Be able to draw the formation of a triglyceride from glycerol and 3 fatty acids.
Know the importance of the primary structure of proteins in determining their tertiary structure.
Know all of the tertiary structure bond types.

Key Terms

Check that you know all of the terms in the Subject Vocabulary boxes on pages 15 and 21 and add any you don’t know to your glossary.