1. Ch. 3: Biochemistry Section 2

2. Molecules of Life
Four main classes of organic compounds are essential for life processes of living things:
Carbohydrates
Lipids
Proteins
Nucleic Acids

3. Carbohydrates
Carbohydrates- Organic compounds composed of carbon, hydrogen and oxygen
1:2:1 ratio
Serve as sources of energy or structural components
Monosaccharides, disaccharides, and polysaccharides

4. Carbohydrates Monosaccharides Disaccharides Polysaccharides
Simple sugar; 1:2:1 ratio of atoms
Disaccharides
Monosaccharides combine to form a double sugar
Polysaccharides
Complex molecule of 3 or more monosaccharides

5. Carbohydrates

6. Types of Polysaccharides
Glycogen
Animals store glucose in the form of glycogen
Used for energy storage
Starch
Plants store glucose in the form of starch
Cellulose
Plants use cellulose as a structural component
Gives strength and rigidity to plant cells

8. Proteins
Proteins: composed mainly of carbon, hydrogen, oxygen, and nitrogen
Formed by the linking of monomers called amino acids
Ex: hair, horns, skin, muscles, enzymes (catalysts)

9. Proteins Amino Acids 20 different amino acids
All share the same basic structure
Central carbon
Single hydrogen
Carboxyl group (--COOH)
Amino group (NH2)
R group (what distinguishes different amino acids)

10. Proteins R groups Can be simple or complex
Differences among the R groups of amino acids gives proteins their different shapes
Different shapes allow proteins to carry out many types of activities

11. Proteins Dipeptide Polypeptide
Two amino acids linked together through a peptide bond
Polypeptide
Long chains of amino acids
Polypeptide chains and resulting proteins can have different shapes depending upon types of bonds, temperature, solvents, etc.

12. Proteins
Enzymes
RNA or protein molecules that act as biological catalysts
Essential for any cell to function properly
Many enzymes are proteins

13. Proteins
Enzymes
Enzyme reactions depend on a physical fit between the enzyme and its specific substrate, the reactant being catalyzed
Enzymes have folds, called an active site, where the substrate fits.
Only specific substrates are acted upon
Only that substrate fits in that active site

14. Proteins Enzymes Continued
Enzymes bind to a substrate, the enzyme changes shape slightly  weakening bonds of substrate
One way enzymes reduce activation energy
Once reaction is completed, the enzyme releases the new product
IMPORTANT: the enzyme itself remains unchanged, and can be used many times

15. Enzyme Reaction

16. Lock and Key

17. Lipids Lipids: large, nonpolar organic molecules
Include triglycerides, phospholipids, steroids, waxes, and pigments
Do not dissolve in water
Large amounts of C-H bonding means they store more energy per gram than any other macromolecule per

18. Lipids Fatty Acids Unbranched carbon chains that make up most lipids
The two ends of a fatty acid have different properties
Head (carboxyl group C-O-O-H) is hydrophilic (water loving)
Tail (C-H chains) are hydrophobic (water hating)

19. Lipids
Saturated vs. Unsaturated

20. Lipids Triglycerides Three fatty acids attached to an alcohol glycerol
Can be saturated and unsaturated

21. Lipids Phospholipids Two fatty acids attached to a glycerol molecule
The cell membrane is made up of two layers of phospholipids, called the lipid bilayer
Hydrophobic tails and hydrophilic heads
Forms a barrier between outside and inside of cell

22. Lipids
Waxes: waterproof, and help provide a protective coating for plants’ outer surfaces.
Human ex: ear wax helps protect ear canal
Steroids: Fused carbon rings; many animal hormones are steroids. Most common animal hormone is cholesterol

23. Nucleic Acids
Nucleic Acids: very large and complex molecules that store and transfer information in the cell
DNA: contains info about characteristics or organisms and directs cell activities
RNA: stores and transfers info from DNA in order to manufacture proteins. Can also act as enzymes

24. Nucleotide: made of sugar, nitrogenous base, and phosphate group

25. Monomers and Polymers of Macromolecules