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• Why do we spend time in biology studying chemicals?

• Why do we have to eat?• What happens to the food we eat?• What organic molecules did you eat

today?• Name a protein, a carb, and a lipid.

Biochemical Processes

♦ All organisms need both energy and chemicals for survival.

Once chemicals are inside an organism they are changed in different ways to maintain homeostasis.

♦Because we can’t always use chemicals the way they exist, we use the following processes:

1. Digestion2. Synthesis3. Respiration4. Photosynthesis

1. Digestion

• when we eat food the molecules are too large to enter our cells; as a result our digestive system changes the larger molecules into smaller molecules

Large Digested to Small Carbohydrates simple sugars (glucose)

Proteins amino acids

Lipids fatty acids and glycerol

2. Synthesis

• after digestion you have small molecules in your cells; some of these molecules will be put together to form larger molecules to make structures such as hair and nails, hormones, and enzymes

Synthesis is the opposite of digestion.

3. Respiration

• as mentioned previously, after digestion you have small molecules such as glucose in your cells. Some of this glucose combines with oxygen in the mitochondria of cells to release energy needed to run the cell. This energy is stored in ATP.

4. Photosynthesis

• plants and algae use light energy to convert simple inorganic compounds into food which is organic

• What do plants need?

water + light + CO2

• What do plants make?

food (glucose) + O2

Chunk!

• What do living things need to survive?• Why do the chemicals need to be changed?• Name the 4 processes that change chemicals.• Define digestion. Why is it necessary?• Name the 3 large molecule types, and what they

are digested into.• Define synthesis. Why is it necessary?

• What happens during respiration?• Where does respiration occur?• What is the energy molecule?• Define photosynthesis.

Enzymes

• None of the reactions described above could occur without the action of enzymes known as catalysts.

These important proteins speed up reaction rates in our bodies without a high temperature.

Enzymes are used repeatedly to catalyze reactions.

• Enzymes are catalysts, substances that speed up the rate of a chemical reaction without themselves being changed or used up during the reaction.

• Enzymes are capable of carrying out the same function over and over bc they are not changed.

• You can use this characteristic of enzymes – that they themselves are not changed – to recognize the enzyme in a diagram.

• Enzymes like other molecules (hormones, antibodies, receptors on cell membranes) have specific shapes that determine how they function.

• Enzymes are chain-like protein molecules that are folded into precise shapes.

• Some molecules called substrates match precisely with the shape of certain enzymes, others don’t fit.

For example, the enzyme pepsin in your stomach acts on protein you eat to digest it.

Pepsin is not effective in digesting fat.

Chunk

• What is another name for enzymes?• What do enzymes do?• What happens to enzymes during reactions?• Can enzymes be used again?• How can you recognize an enzyme in a diagram?• Enzymes, hormones, neurotransmitters, and

antibodies all function by ___________.

Chunk some more…

• The molecule an enzyme works on is called…• Why will pepsin just digest protein, nothing

else?• What kind of molecule is an enzyme?• Describe the enzyme-substrate complex.• What are the molecules that are the result

called?

A

A

B

C

D D

E

F F

Computer simulation of an enzyme that works on oxygen

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