Biology
Class Notes
3-2
Topic: Biochemistry
Aim: Why are organic compounds important for living things?
**organic chemistry: study of all compounds that contain carbon
(A) Carbon
 Carbon atoms have 4 valence electrons
 Can bond with many elements and can bond with other
carbon atoms to form very long chains
 Can form millions of different structures
(B) Macromolecules
 Made up of thousands of smaller molecules
 Monomers=one molecule
 Polymers=many molecules
 Monomers become polymers through polymerization
 Four groups of organic compounds found in living things
1. Carbohydrates
 Made up of C, H, O in a 1:2:1 ratio
 **Living things use carbs as their main source
of energy
 plants and some animals use carbs for
structural purposes
glucose
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2. Lipids
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monosaccharide: single sugar molecule—
glucose, fructose, galactose
polysaccharide: large macromolecules
made up of monosaccharides—starch—
stored as glycogen
plants use a different polysaccharide—
cellulose
Not soluble in water
Made mostly from C and H
Fats oils and waxes
Serve as long term energy storage
Make up biological membranes
Made up of glycerol and fatty acids
3. Nucleic Acids
 H, O, N, C, P
 Polymers made up of monomers called
nucleotides
 Store and transmit cellular information
 DNA and RNA
4. Proteins
 C, H, O, N
 Made up of amino acids
 Each protein has a specific role in our body
 Control the rate of reactions, regulate cell
processes, form bone and muscles, transport
substances