2-4 Chemical Reactions

& Enzymes

Chemical Reactions

• Changes or transforms one

set of chemicals to another

• The chemicals you start

with are called the

reactants

• The compounds or

elements made by the

reaction are the products

Energy in Reactions

• The amount of energy

needed to start a

reaction: activation

energy

Catalyst

• A catalyst is a

substance that

speeds a chemical

reaction.

• Catalyst work by

lowering reaction’s

activation energy.

Enzymes

• Enzymes are proteins that act as biological catalysts.

• Cells use enzymes to speed up chemical reactions that take place in cells.

• Enzyme speed up reactions by lowering the activation energies.

• An enzyme will only catalyze (speed up) one reaction, therefor there are thousands of different enzymes

Note:

Enzymes

end in

ase Catalase

Amalase

Enzymes

• A place where

substrates come

together to react

• Reduces the energy

needed for a reaction

to occur.

All enzymes have an active site,

where substrates are attracted to.

• Enzymes are used over and over again.

Substrate

• The substance

changed or acted

upon by an enzyme is

the substrate.

The Enzyme Substrate complex

• Enzyme and substrate fit together like a puzzle.

• The active site shape matches the substrates shape.

• The substrate and active site meet and change the shape of the active site causing a reaction and a product is made

Which one will fit ?

• Enzymes are specific

to one type of

reaction!!!

The factors that affect enzyme

activity are

• pH

• Temperature

• Amount of substrate

Affects of temperature on an

enzyme

• If temp too high or too

low the enzyme will

not fit. No reaction

will occur.

How pH affects an enzyme

• If the pH is too high or

low the enzyme will

not work, because its

shape will change.

pH

• Optimal pH.

• pH too low or too high, the enzyme changes shape

• No reaction

Analyze the graph at what ph does

Chymotrypsin function best?

Temperature

• Optimal Temperature

• Enzymes and substrates move quicker and connect more often.

• If the temp is too high the enzyme will be destroyed.

What is the optimal temp for this

enzyme

Amount Of Substrate Present

• Not enough: less reaction

• More substrate= more reaction.

• This continues until the enzymes are saturated.