Chemical Reactions &

Enzymes

Essential Questions

How do energy changes affect whether a chemical reaction will occur?

Why are enzymes important to living things?

Chemical Reactions When one set of chemicals change into

another set of chemicals

Reactants Products

Ex. CO2 + H2O H2CO3

carbon dioxide + water carbonic acid

Enzymes -proteins that act as catalyst by

speeding up chemical reactions

Enzymes can make or break bonds within molecules.

Is the enzyme in this picture making or breaking bonds?

Enzymes function as catalysts.

A catalyst is a substrate that speed up chemical reactions by lowering the activation energy needed.

Find the enzyme (catalyst) in the picture.How do you know it is the enzyme?

Enzymes function by lowering the activation energy of reactions.

Activation energy is the energy that is needed to get a chemical reaction started What is the activation energy in the picture below?

If you said the “push” you are right.

Think of an enzyme as something that helps “push” a reaction along. The bear would get the rock over faster if it had a helper.

If you had to push the rock over the hill in this graph, which hill would take less time?

The red line is the reaction occurring with an enzyme catalyst (helper). Less energy is needed.

Enzymes function based on their shape. (Lock & Key)

The orange material in this picture is going to be broken down by the enzyme (purple).

The molecule that the enzyme works on is known as the substrate.

The enzyme and the substrate must fit together in order for the enzyme to work.

Enzymes can act rapidly, one enzyme in your body is known to cause the chemical to react 107 times faster than without the enzyme present.

There are over 2000 known enzymes, each of which is involved with one specific chemical reaction. Therefore, they have 2000 different shapes. (Lock & Key)

Common Enzymes in your Body

Amylase – in your mouth breaks down sugar

Peptidase- in your stomach break down proteins

Lipase- in your small intestine break down lipids

–ase means enzyme What does –ose mean?

Look again at the picture below.

If the substrate below is a disaccharide (two sugars) than what is the product of this reaction?

The products (or what is produced) would be monosaccharides (single sugars).

If the substrate was a protein, what would the product be?

Amino Acids

Because we know that proteins are made of amino acids.

Temperature: temperature increase speeds of enzyme reactions,

but only to a point. When heated too much, enzymes become denatured (or destroyed).

Changes in pH will also denature the enzyme

Concentration of Substrate