Enzyme FunctionEnzyme Function

D. Crowley, 2007D. Crowley, 2007

Enzyme FunctionEnzyme Function

To know what can affect how well an enzyme worksTo know what can affect how well an enzyme works

AbsorptionAbsorption Digested food molecules are absorbed through the small Digested food molecules are absorbed through the small

intestine (into our blood)intestine (into our blood)

Once in the blood, the digested food molecules are carried Once in the blood, the digested food molecules are carried around the body, to where they are neededaround the body, to where they are needed

Only small, soluble molecules can pass through the wall of Only small, soluble molecules can pass through the wall of the small intestinethe small intestine

VilliVilli

The inside wall of the small intestine needs to be thin, with a The inside wall of the small intestine needs to be thin, with a really big surface areareally big surface area

This allows absorption to happen quickly and efficiently (so we This allows absorption to happen quickly and efficiently (so we absorb as much food as possible)absorb as much food as possible)

To get a big surface area, the inside wall of the small intestine To get a big surface area, the inside wall of the small intestine is lined with tiny is lined with tiny villivilli (one of them is called a (one of them is called a villusvillus))

These stick out and give a These stick out and give a big surface area. They also big surface area. They also contain blood capillaries to contain blood capillaries to carry away the absorbed carry away the absorbed food molecules.food molecules.

Enzyme FunctionEnzyme Function

Enzymes only break down one type of food – e.g. Enzymes only break down one type of food – e.g. lipase only breaks down fat (lipids); amylase only lipase only breaks down fat (lipids); amylase only breaks down carboydrates; protease only breaks down breaks down carboydrates; protease only breaks down proteinprotein

The rate at which enzymes break food down can be The rate at which enzymes break food down can be affected by two main factors: -affected by two main factors: -– pHpH– TemperatureTemperature

What do you think the optimum temperature if for What do you think the optimum temperature if for enzymes in the body?enzymes in the body?

What about pH?What about pH?

ExperimentExperiment

Trypsin is an enzyme which breaks down proteinTrypsin is an enzyme which breaks down protein

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

You need to carry out an experiment to find out how You need to carry out an experiment to find out how the temperature of the Tryspin affects how quickly the the temperature of the Tryspin affects how quickly the milk is broken downmilk is broken down– You will have 3 boiling tubes of milkYou will have 3 boiling tubes of milk– To each you will add some Tryspin which is at To each you will add some Tryspin which is at

different temperaturesdifferent temperatures– You need to time how long the solution went from You need to time how long the solution went from

being cloudy to translucentbeing cloudy to translucent

ProcedureProcedure

Take 3 boiling tubes, and fill them each with 10ml of Take 3 boiling tubes, and fill them each with 10ml of milk – place them in a rackmilk – place them in a rack

Add Add 10ml10ml of of cold Trypsincold Trypsin to to oneone boiling tube with milk boiling tube with milk in, and begin the timer – time how long it takes for the in, and begin the timer – time how long it takes for the solution to become transparentsolution to become transparent

Repeat this with the second boiling tube, but this time Repeat this with the second boiling tube, but this time add add 10ml warm Trypsin10ml warm Trypsin

Repeat this with the third boiling tube, but this time Repeat this with the third boiling tube, but this time add add 10ml boiling Trypsin10ml boiling Trypsin

Record all your resultsRecord all your results

ExplanationExplanation

Explain why when the Trypsin was cold the solution Explain why when the Trypsin was cold the solution turned clear slowlyturned clear slowly

Explain why when the Trypsin was warm the solution Explain why when the Trypsin was warm the solution turned clear quicklyturned clear quickly

Explain why boiling the Trypsin caused the solution to Explain why boiling the Trypsin caused the solution to remain cloudyremain cloudy

TemperatureTemperature

This experiment shows that enzymes work best at a This experiment shows that enzymes work best at a given differentgiven different

If it is too cold the enzyme takes a long time to break If it is too cold the enzyme takes a long time to break the food molecules downthe food molecules down

But if it is too hot the enzyme may not function at all – But if it is too hot the enzyme may not function at all – it has been it has been denatureddenatured

Enzymes in the human body usually denature above Enzymes in the human body usually denature above 4545ooCC