Chemical Reactions & Enzymes: Chapter 2.4

Chemical reaction

• changes one set of chemicals into another

• Occur when the bonds between atoms are changed

• Reversible

Reactants

Materials that enter a reaction

Products

Materials that are made in a reaction

Energy

• Needed for chemicals reactions of occur (release/absorb energy)

• Heat provides it to start a reaction

Activation energy

The energy needed to start a chemical reaction

Enzymes

Proteins that speed up chemical reactions by lowering the activation energy

Substrate

Molecule that an enzyme reacts with

Active site

The part of the enzyme where substrates bind and a chemical reaction takes place.

Enzyme Example

Lactose —> Galactose + Glucose

• lactose (diasaccharide) must be broken down (digested) into the monosaccharides galactose and glucose

• Your body needs the enzyme Lactase to do it

Enzyme activity is affected by

• changes in pH and temperature

• High/low pH and temp can denature the enzyme preventing it from binding to the substrates

Enzymes . . .

• Only reacts with specific substrates

• can be used again and again after reactions

Lactase

• An enzyme

• speeds up the process of breaking down lactose