2.4 Chemical Reactions and

Enzymes

What is a chemical reaction? A process that changes one set of chemicals

into another Some bonds are broken and new bonds are

formed http://www.youtube.com/watch?v=4N0m95PEx

HY&feature=related

Chemical Reactions

Some release energy

Gets hot Ex: the foam experiment

Some use energy Gets cold Ex: instant ice pack

Some reactions are fast Some reactions are slow

Chemical reactions and energy

Our bodies need them to happen inside of us

to survive. (so do all living things)

Why should we care about chemical reactions??

Chemical reaction in the lungs

A chemical reaction allows you to get rid of carbon dioxide from your blood so you can breathe it out.

Chemicals in your saliva help you to start breaking down starch in your food.

Chemical reaction in your mouth!

Chemical

reactions in your stomach help you to break down food to get energy

Chemical reactions in your stomach

In order to stay alive, organisms need energy

to carry out reactions inside of them. The amount of energy needed to get a

chemical reaction started is called “activation energy” Ex: lighting paper on fire.

Many chemical reactions need ENERGY, and they

won’t just happen on their own!!!

If you had to

use a ton of activation energy for every single reaction in your body, your body would never get anything done.

Many reactions need a lot of activation

energy

We need a helper…

Enzymes. Enzymes are proteins that speed up chemical

reactions so that you don’t need a ton of activation energy. Aka “catalysts”

What can we use INSTEAD of a ton of activation energy?

Normally, reactants would have to find each

other and hit each other with a bunch of energy in order to react.

Enzymes have a specific spot on them where they can bring reactants together to react, so that doesn’t have to happen

Enzymes weaken the bonds of reactants, too. http://www.youtube.com/watch?v=V4OPO6JQL

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How an enzyme works

The reactants in a reaction sped up by

catalysts are called substrates. Catalysts and substrates bind together like a

lock and key

Enzymes are particular

They require specific temperature, pH, and other molecules to work properly.

http://www.youtube.com/watch?v=3UsCRN6D

M3Y

http://www.youtube.com/watch?v=XTUm-75-PL4&feature=related pilot video

http://www.youtube.com/watch?v=feik6wOXFA0

Enzymes video