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Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biologi cal catalys ts Increase the rate of chemical reactions Remain unchanged by chemical reaction

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Page 1: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

Cells & Enzymes

Enzymes

Made of protein Present inall living cells

Converts substratesinto products

Biological catalysts

Increase the rate of chemical reactions

Remain unchanged by chemical reaction

Page 2: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

• This term really means two things:

ANABOLISM and CATABOLISM

METABOLISM

Page 3: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

ANABOLISM

“ TO BUILD” molecules as in the biosynthesis of polymers..

We ingest food digest to monomers and THEN via ANABOLISM we make larger molecules

Page 4: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

• “TO BREAK APART “

• Example: Glycogen, (starch) stored in the liver when needed for energy, is converted to glucose ( monomers).

So during catabolism large molecules are broken into smaller molecules.

Catabolism …then is to..

Page 5: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

ProductSubstrate

Chemical Reactions

A chemical reaction takes place when one or substances is chemically changed into one or more different substances.

Chemical reactions take place in cells all the time.

Enzyme

Catalase

Hydrogen peroxide

Water + oxygen

Manganesedioxide

Catalyst

Page 6: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

Enzymes and Chemical ReactionsEnzymes can speed reactions by lowering the amount of energy needed for a chemical reaction

Page 7: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

Catalysts

A catalyst is a substance which speeds up a chemical reaction, without itself being changed by the reaction.

1. When a catalyst is present, less energy is needed to get the chemical reaction started.

2. When a catalyst is present, the speed of the chemical reaction is faster.

3. Although a catalyst helps a chemical reaction to happen, it is unchanged at the end of the reaction.

Page 8: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

Biological Catalysts

The biological catalyst present in the cytoplasm of plant and animal cells that speeds up the breakdown of hydrogen peroxide is called CATALASE.

Hydrogen peroxide

Oxygen + watercatalase

REACTANTS PRODUCTS

enzyme

Page 9: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

2.2 Nature of Enzymes

The biological catalyst present in the cytoplasm of plant and animal cells that speeds up the breakdown of hydrogen peroxide is called CATALASE.

Catalase cannot speed up any other reaction. It is SPECIFIC to this reaction.

CatalaseHydrogen peroxide

Water + oxygen

Page 10: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

One Enzyme – One Reaction

There are thousands of different enzymes in your body.

Why are there so many different enzymes?

Each enzyme has its own unique protein structure and shape, which is designed to match or COMPLEMENT its substrate.

Page 11: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical
Page 12: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical
Page 13: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

Lock & Key Hypothesis

An enzyme only acts on one type of substance, or substrate.

Therefore, the enzyme is said to be SPECIFIC to its one substrate.

The shape of the active site (binding site) of the enzyme, matches the shape of the substrate. Allowing the two molecules to bind during the chemical reaction.

This theory of enzyme action is called the ‘lock-and-key’ hypothesis.

Page 15: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

Different enzymes for different jobs

Enzymes involved in breakdown reactions

Enzyme and substrate separate

Enzyme-substrate complex

Enzyme and products separate

Enzymes involved in synthesis reactions

Enzyme and substrates separate

Enzyme-substrates complex

Enzyme and product separate

Page 16: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

2.3 Using a Control

Why is it necessary to include a control experiment in an investigation?

A control is an experiment that allows a comparison within an investigation in order to ensure that the conclusions drawn from the results are valid.

Page 17: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

Enzymes involved in breakdown reactions

CatalaseHydrogen peroxide Water + Oxygen

AmylaseStarch Maltose

LipaseFat Fatty acids + Glycerol

PepsinProtein Amino acids

Page 18: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

2.5 Effect of High Temperature

Notes on Denaturation Notes on Optimum temp

• Optimum conditions are the conditions at which an enzymes works best

• Rate of reactions may be affected by temperature and pH

Page 19: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

2.5 Effect of High Temperature

Notes on DenaturationNotes on

Optimum temp

What happens to the activity of an enzyme at high temperatures?

Page 20: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

Movie

Effect of pH on enzymes

When the pH changes outwith optimal conditions, the shape of the active site of the enzyme alters and the enzyme is denatured.

Page 21: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

Effect of pH on enzyme activity

Most enzymes work best at a pH close to neutral (pH7), but there are some exceptions. Pepsin, an enzyme found in the stomach, has an optimum pH of 2.

Page 22: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical
Page 23: Cells & Enzymes Enzymes Made of protein Present in all living cells Converts substrates into products Biological catalysts Increase the rate of chemical

Enzyme Substrate Product(s) Degradation or synthesis?

Amylase Starch Maltose

Catalase Hydrogen peroxide

Oxygen and water

Pepsin Protein Amino acids

Phosphorylase Glucose-1-phosphate

Starch s

Lipase Fat Fatty acids

Enzyme Summary