Noadswood Science, 2012

Enzymes & pHTo investigate the effect of pH on enzymes

Tuesday, April 11, 2023

Digestive System

EnzymesWhat are enzymes?

Enzymes are biological catalysts - catalysts are substances that increase the rate of chemical reactions without being used up

Enzymes are specifically proteins that are folded into complex shapes that allow smaller molecules to fit into them – the place where these substrate molecules fit is called the active site

Enzymes If the shape of the enzyme changes, its active site may no

longer work – the enzyme has been denatured

They can be denatured by high temperatures or extremes of pH

*It is wrong to say the enzyme has been killed – although enzymes are made by living things, they are proteins, and not alive

Life In Cold BloodHow does temperature affect feeding – consider cold and

warm blooded animals…

As the temperature increases, so does the rate of reaction

The enzyme activity gradually increases with temperature until around 37°C

Enzymes & pHChanges in pH alter an enzyme’s shape

Different enzymes work best at different pH values – the optimum pH for an enzyme depends on where it normally works

E.g. intestinal enzymes have an optimum pH of about 7.5 and enzymes in the stomach have an optimum pH of about 2

Trypsin & pHTrypsin is an enzyme which breaks down protein

If Trypsin is added to milk it will break down the milk, turning it from cloudy to translucent

You need to carry out an experiment to find out how the pH of the medium affects how quickly the Tryspin breaks down the milk

You will have 3 boiling tubes of milk (in different pH conditions)

To each you will add some Tryspin

You need to time how long the solution went from being cloudy to translucent

Trypsin & pHTake 3 boiling tubes, and fill them each with 10ml of milk –

place them in a rack

To each boiling tube add 20ml of a different pH solution (acidic, neutral and alkaline)

Add 10ml of Trypsin to each boiling and begin the timer – time how long it takes for the solution to become transparent for each test

Record all your results

Quiz