Lesson Starter What is the name of the muscular tube which connects the mouth and stomach? Describe the process of peristalsis Describe the role of churning in the stomach

Learning Intention To be able to explain where pepsin is produced To be able to describe the role of pepsin To investigate the effect of pH on pepsin

Optimum conditions for enzymes The more ACTIVE an enzyme is, the faster the REACTION RATE Enzyme at its most active- OPTIMUM CONDITIONS Temperature pH Out with optimum- not enough/ dentaure

Optimum temperature Enzymes are everywhere (not just inside us) Body enzymes- 37°C Before 37°C- not enough energy, few collisions, UNDAMAGED 35-40ish°C- WORKING RANGE- enzyme works, OPTIMUM=37°C >40°C- DENATURED, lost shape, lock and key

What is pH?

Optimum pH Different enzymes have a different working range Acid Neutral Alkaline

Pepsin Digestive enzyme Produced in the stomach Speeds up breakdown of protein Peptides

Pepsin experiment- overview Observe the change in disks of egg white (protein) when pepsin is added at 3 different pHs.

Pepsin experiment (copy and complete) AIM To find out the OPTIMUM pH for the enzyme PEPSIN Hypothesis What do you expect to happen in this experiment? I think that pepsin will work best in _______ conditions

Experiment Instructions *WEAR YOUR GOGGLES* Apparatus 3 x test tubes Test tube rack Bottle of pepsin Bottle of acid Bottle of alkali Bottle of neutral 3 x egg white disks labels Instructions *WEAR YOUR GOGGLES* Collect apparatus Label your 3 test tubes- (acid, alkali, neutral) Place a disk of egg white in each test tube Cover each disk with PEPSIN Add 5mls of acid to the test tube labelled acid (alkali to alkali, neutral to neutral) Place in water bath at 40°C Leave for 15-20 mins (clear up chemicals) Examine the appearance of egg white

Method Apparatus list- write down a list of all the chemicals and equipment that you used Step by step instructions- write down instructions that someone else could follow to do this exact experiment Diagram- Draw a LABELLED diagram using a RULER to show how the set up is arranged

Results Describe the appearance of your egg white in each of the test tubes (stating which pH they have been in at) Conclusion What is the optimum pH for pepsin? How do you know? Did your hypothesis agree with the results? Explain why it is important that pepsin works best at this pH, considering where it is found in the body.