A Level Biology Lesson 12:

Proteins: The 4 Levels of Protein Structure.

Task 1. Check Where this Lesson fits into your Exam Specification!

Task 2. Watch the Revision Notes Lesson in Full.

00:00 Learning Outcomes

00:28 Introduction.

01:30 The primary Structure (polypeptide chain).

02:22 The Secondary Structure (alpha-Helices and Beta-Pleated Sheets).

04:05 The Tertiary Structure (bonds - Hydrogen bonds, Ionic bonds and Disulfide bridges).

05:05 The Quaternary Level of Protein Structure (Haemoglobin, Insulin and Collagen).

Task 3. 

Download, Print out & complete the accompanying Interactive Worksheet.


Check Your Spec!


★ AQA Specification Reference: - General properties of proteins. A functional protein may contain one or more polypeptides. The role of hydrogen bonds, ionic bonds and disulfide bridges in the structure of proteins. Proteins have a variety of functions within all living organisms. The relationship between primary, secondary, tertiary and quaternary structure, and protein function.


★ CIE Specification Reference: - 2 Biological molecules (2.3 Proteins) b) explain the meaning of the terms primary structure, secondary structure, tertiary structure and quaternary structure of proteins and describe the types of bonding (hydrogen, ionic, disulphide).


★ Edexcel (Biology A – Salters-Nuffield) Specification Reference: - Topic 2: Genes and Health - 2.9 iii) Understand the significance of a protein’s primary structure in determining its three-dimensional structure and properties (globular and fibrous proteins and the types of bonds involved in its three-dimensional structure).


★ Edexcel (Biology B) Specification Reference: - Topic 1: Biological Molecules - 1.3 Proteins Understand the significance of the primary, secondary, tertiary and quaternary structure of a protein in determining the properties of fibrous and globular proteins, including collagen and haemoglobin. Understand the role of ionic, hydrogen and disulfide bonding in the structure of proteins.


★ OCR (Biology A) Specification Reference: - 2.1.2 Biological molecules (m) the levels of protein structure. To include primary, secondary, tertiary and quaternary structure AND hydrogen bonding, disulfide bonds and ionic bonds.


★ OCR (Biology B) Specification Reference: - 2.1.3 Proteins and enzymes (b) the molecular structure of globular proteins as illustrated by the structure of enzymes and haemoglobin. To include primary, secondary and tertiary structure in relation to enzymes, and quaternary structure and prosthetic groups in relation to haemoglobin.


★ WJEC Specification Reference: - 1. Basic Biochemistry and Cell Organisation (i) the primary, secondary, tertiary and quaternary structure of proteins.

Remember Specifications are often very vague - No matter which exam board you are studying you need to know this.



Darwin T




1Fractured DNA



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