Lipids and Chemical Reactions

Lipids aka: fats, oils, and waxes

Lipids, including fats, oils, and waxes, are polymers composed of 3

atoms:

carbon, hydrogen, and oxygen

While made up of the same atoms, lipids are VERY different from

carbohydrates:

1. Lipid molecules are made of two monomer molecules

glycerol and fatty acids

2. Fats/lipids have more carbon-hydrogen bonds than carbohydrates

this is why lipids have the highest caloric value!!

Lipid Images

Lipids many functions

1. Provides long-term energy

2. Cushions vital organs

3. Insulates/warms the body

4. Major component of cell

membranes

5. Used in making some vitamins

and hormones

*Lipids are important to organisms for energy

when carbohydrates are scarce*

Compounds and Calories

The caloric value (calorie value) of each organic compound is

determined by its stored energy

Proteins, carbohydrates, and fats/lipids are the 3 organic

molecules with different structures and different caloric values based

on those structures

Proteins- 4 calories per gram

Carbohydrates- 4 calories per gram

Fats/lipids- 9 calories per gram

Look at the label to the left. 3 of

the 4 macromolecules can be

found in foods... These are the

ones we will focus on!

The 3 biochemical molecules

found on a nutrition label are:

1____________________

2____________________

3____________________

(0 grams in this product)

(13 grams in this product)

(9 grams in this product)

Think About it • When you hear the term “Chemical

Reaction,” what comes to mind?

Chemical Reactions

• Chemical reactions

change substances

into different

substances

HOW?

• breaking and

forming chemical

bonds.

Chemical Bonds • The oxygen you breathe (O2) is

involved in reactions that break down

the simple sugar glucose (C6H12O6). o The process uses oxygen and glucose and results

in carbon dioxide (CO2), water (H2O), and usable

energy.

o Oxygen and glucose are the reactants – the

substances that are changed during a chemical

reaction.

o Carbon dioxide and water are the products

• The substances made by a chemical reaction.

• The oxygen you breathe (O2) is

involved in reactions that break down

the simple sugar glucose (C6H12O6). o The process uses oxygen and glucose and results

in carbon dioxide (CO2), water (H2O), and usable

energy.

o Oxygen and glucose are the reactants – the

substances that are changed during a chemical

reaction.

o Carbon dioxide and water are the products

• The substances made by a chemical reaction.

• In the equation below for cellular respiration, bonds

must be broken in the reactants, and bonds must

form in the products.

C6H12O6 + 6O2 -> 6CO2 + 6H2O

REACTANT PRODUCT

Chemical reactions release or absorb energy.

• Some energy must be absorbed by the reactant in

any chemical reaction.

• Activation energy is the amount of energy needs to

be absorbed for a chemical reaction to start.

• An exothermic reaction releases more energy than

it absorbs.

o These reactions are usually “breaking down” something,

like cellular respiration does.

o These reactions give off excess energy, usually in the form

of heat or light.

• An endothermic reaction absorbs more energy

than it releases.

o These reactions are usually “making” something, like

photosynthesis does.

o Sometimes these reactions will feel cold.

• Question: Do you think the glow that a firefly gives

off is an example of an exothermic or an

endothermic reaction?