Biology / Unit 1: The Science of Biology and Chemistry of Life
1.4 Carbohydrates and Lipids
Notes
Large biological molecules are called macromolecules. Most are polymers made of repeating units called monomers.
- Carbohydrates (sugars and starches) are made of C, H and O. Monomer: monosaccharide such as glucose ($\text{C}_6\text{H}_{12}\text{O}_6$).
- Carbohydrates supply quick energy; starch (plants) and glycogen (animals) store it; cellulose forms plant cell walls.
- Lipids (fats, oils, waxes, steroids) do not dissolve in water. They store long-term energy, insulate, and form cell membranes (phospholipids).
- A typical fat is built from glycerol and fatty acids. Saturated fats are solid at room temperature; unsaturated fats (oils) are liquid.
Practice
Which molecule is a monomer of carbohydrates?
Glucose is a monosaccharide, the building block of starch, glycogen and cellulose.
A seal has a thick layer of blubber under its skin. Which macromolecule is this mostly made of, and what does it do?
Blubber is fat, which stores energy and keeps heat in.
Cellulose and starch are both made of glucose. What is cellulose's main job?
Cellulose is a structural carbohydrate in plant cell walls.
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