Enzyme Activities Kate Andrews Tricia Geraghty Simple activities

Enzyme Activities Kate Andrews Tricia Geraghty

Simple activities to support the teaching and learning of enzymes at various levels in the curriculum.

Effervescent Enzymes Background • Hydrogen peroxide - a damaging substance produced by living cells. • Cells produce catalase, an enzyme, to remove hydrogen peroxide.

Catalase speeds up the breakdown of hydrogen peroxide: hydrogen peroxide + catalase oxygen + water In solution, bubbles of oxygen gas are produced - effervescent enzymes!

Aims of activity 1 To: • Identify whether catalase is present in both living and non-living substances • Compare catalase activity in a variety of plant and animal tissues

The process. . . 1. Touch a filter paper disc against the freshly cut surface of a non-living substance, plant or animal tissue. 2. Drop disc into a solution of hydrogen peroxide – it should sink 3. If catalase present hydrogen peroxide broken down 4. Oxygen bubbles attach to the disc causing the disc to become buoyant.

Comparisons. . Time to float related to how quickly oxygen is produced - hence which tissue contains the most catalase.

Work in pairs. Wear eye protection. Carry out activity 1. Note your results.

Aims of activity 2 To investigate the effect of increasing enzyme concentration on enzyme activity using : - a series of dilutions of yeast cells, or unicellular algae

The process…. The same as activity 1 except one drop of each dilution of cells is placed on a filter paper disc.

Some uses of catalase

- Protocols adapted from Roger Delpech ‘Microscale Investigations with Catalase’ - Ideas for investigations suitable for Advanced Higher projects. - http: //www. saps. org. uk/attachments/article/293/SAPS%20 Student%20 Sheet%20 -%2024%20%20 Investigations%20 with%20 Catalase. pdf

An oldie, but a goodie! The Breakdown of Starch by Diastase • Simple activities • Strikingly visual results – easy to record in a variety of ways • Used to develop understanding of enzyme properties • Ideal for discussion of experimental design – variables, controls, conclusions

Based on the action of diastase on starch diastase starch maltose

The process. . . Starch agar well cut in agar with cork borer and filled with diastase Leave set up for 24 hours

What you might see. . Flood the plate with iodine solution and rinse iodine solution becomes blue-black clear area where starch has been broken down

Do barley seeds contain enzymes? diastase solution halved germinating barley seeds, halved and boiled

• barley grains mashed in water • water as a control

Set up diastase experiments

The problem with lactose. . . .

Protocol adapted from an NCBE protocol: Better Milk for Cats, (1995)

The Problem with Lactose. . . . Lactase, a digestive enzyme, speeds up the breakdown of lactose (sometimes called milk sugar) lactase Lactose glucose + galactose

Aims of the activity To: • To provide a context for developing understanding of enzymes and their uses in industry • To demonstrate a use of ‘immobilised enzymes’ • To provide a context for identifying ‘limitations and improvements. . . ’

The context. . • Cats are fond of milk? • Many cats cannot tolerate cow’s milk - it makes them sick • Pet food manufacturers have produced ‘cat-safe’ milk

A trivial problem? ? • Lactose intolerance also affects humans. . • Lactase is used in the production of lactose-reduced milk for cats and humans who have problems digesting lactose

The process Lactose-reduced milk can be produced in two ways: 1. Lactase can be injected into cartons as UHT milk is being packaged 2. Milk can be treated by enzymes which have been ‘immobilised’ on beads of gel

The process. . .

Our design

Further discussion In designing a treatment column for the production of lactose-reduced milk, what factors would a manufacturer have to take into consideration?

Further study / investigation

Curriculum Links I have taken part in practical activities which involve the use of enzymes and microorganisms to develop my understanding of their properties and their use in industries. SCN 4 -13 b

‘S’ Grade -. . carry out an investigation on the catalase reaction when plant and animal tissues are added to hydrogen peroxide solution. Int 2 -. . demonstrate the breakdown of hydrogen peroxide by heating compared to catalysis with manganese dioxide and catalase. Current ‘H’ Human Biology – Effects of various factors on enzyme activity to include inhibition, substrate and enzyme concentration. Carry out an investigation…. .

Revised Higher Biology and Higher Human Biology Unit 2, Human Biology Unit 1: • Activation energy experiments, comparing heat, manganese dioxide and catalase action on hydrogen peroxide. • Experiments on competitive inhibition. • Experiments on reaction rate with increasing substrate concentration.