1. Higher Human Biology Unit 1 – Cell Function and Inheritance Proteins The Role of Enzymes

2. Success criteria By the end of this lesson we will be able to: 1. State what elements are found in proteins 2. Describe what is meant by primary, secondary and tertiary structure of proteins. 3. Give examples of different types of proteins and their uses. √ √ √

3. Protein structure Aim: The aim of this lesson is to understand the structure of proteins, their component parts and their functions.

4. Success criteria By the end of this lesson we will be able to: 1. State what elements are found in proteins 2. Describe what is meant by primary, secondary and tertiary structure of proteins. 3. Give examples of different types of proteins and their uses.

5. Protein elements Proteins are large organic molecules made up of the elements Carbon, Hydrogen, Oxygen and Nitrogen. Proteins will also often contain sulphur.

6. The whole picture Ball and stick model Grey = Carbon Red = Oxygen Blue = Nitrogen Yellow = Sulphur Hydrogen not shown

7. Primary structure The sub-units of proteins are known as amino acids which are linked together into long chains by peptide bonds ValineLeucineIsovalineAlanine Valine Leucine Isovaline Alanine Peptide bond

8. Primary structure There are 20 exciting amino acids to choose from when building a protein.

9. Build a protein Use the amino acid blocks to build a chain which is 20 amino acids long. You can use an amino acid more than once.

10. Primary structure The amino acids in the chain and the order in which they appear is the primary structure of a protein. In living things, this primary structure does not happen by chance but is coded for by DNA. ValineLeucineIsovalineAlanine

11. Secondary structure When the chain is complete it will be long.

12. Secondary structure Weak hydrogen bonds will form between some amino acids in the chain making it coil into a helix. Hydrogen bond

13. Secondary structure The way a protein coils up into a helix is the secondary structure. When a protein winds up into a coil. This is called an ∂ Helix. Proteins with secondary structure are fibrous e.g. Collagen found in cartilage,tendon, skin, and bone.

14. Secondary structure Helices can also be twisted around each other layers with ‘thicken’ the connective fibres e.g. Collagen – 3 alpha helices twisted together Keratin which makes up hair -7 alpha helices twisted together The diagram above shows the three collagen helices twisted together

15. Tertiary structure Proteins can also wind up into tangled shapes using a variety of additional bonds. This will form a globular protein. Enzymes, hormones and antibodies all have a globular structure Keratin in hair has disulphide bonds. If you light a single hair you will smell the sulphur

16. Tertiary structure A globular protein can sometimes contain non protein parts in the tertiary structure. This forms a conjugated protein. Non protein parts Haemoglobin is an important oxygen carrying pigment with a conjugated structure containing iron

17. Examples of proteins Protein nameType of proteinRole CollagenFibrousFound in skin ActinFibrousMuscle cell filaments MyosinFibrousMuscle cell filaments Amalase (Enzyme)GlobularBreakdown of starch into maltose Testosterone (Hormone) GlobularProduces male gender characteristics HaemoglobinConjugated globularFound in red blood cells. Carries oxygen.

18. Now try the following 1. Name the elements are found in all proteins 2. Describe what is meant by each of the primary structure of proteins. 3. Name the bond between amino acids. 4. What additional bond gives secondary structures their shape? 5. What is the main shape formed using secondary structure? 6. Give two examples of proteins made up exclusively from proteins with secondary structure

19. 7. Proteins can also take up a more complex tertiary structure. Describe this. 8. Give two examples of proteins with a tertiary structure and state what each protein is used for. 9. Haemoglobin is an example of a protein with a conjugated structure. Explain what is meant by this. 10. Give the level of structure and the function of each of the following proteins:- Actin Testosterone Keratin Haemoglobin