1. 3-2: MOLECULES OF LIFE
There are 4 classes of organic compounds essential to life:
Carbohydrates
Proteins
Lipids
Nucleic Acids
Each of these compounds are made up of C, H, + O atoms; but occur in different ratios

2. Carbohydrates Organic compounds composed of C, H, + O
Found in ratios of 2H:1O; the # of C varies

3. Carbohydrates (cont.) Monosaccharides
Monomer – a simple sugar (1C:2H:1O ratio)
Formula = (CH2O)n ; where n = 3-8
Common types:
Glucose - - used in cells
Fructose - - found in fruits
Galactose - - found in milk
All have same formula = C6H12O6
Isomers = same formula, different structures

4. Examples

5. Carbohydrates (cont.)
Disaccharide – “double sugar” – combination of 2 monosaccharides from a condensation rxn
Ex. Sucrose

6. Carbohydrates (cont.)
Polysaccharide – complex molecules composed of 3 or more monosaccharides
In animals, glucose is stored as glycogen
Found in branched chains
Stored in liver + muscles

7. Carbohydrates (cont.)
In plants, glucose is stored as starch or cellulose
Starch – found as branched or unbranched chains
Cellulose – gives strength + rigidity to plant cell walls

8. Proteins Organic compounds composed mainly of C, H, O, + N
Formed from monomers
Found in skin, hair, nails + muscles

9. Proteins (cont.) Amino Acids (AA)
Building blocks of proteins – monomer
20 different AA in living things
Difference = functional groups attached to C
R. Groups can be simple or complex
Can take on a variety of shapes, thus carrying out different activities in living things

11. Proteins (cont.)
Dipeptide – the bonding of 2 AAs
Forms a peptide bond

12. Proteins (cont.) Polypeptide – a long chain of AA’s
Chain folds or bends based on certain conditions ( i.e. Temperature increase/decrease) – ex. egg
When polypeptide folds, takes on a globular shape

13. Proteins (cont.) Enzymes
RNA or protein molecules that act as biological catalysts
Work by a “lock-and-key” method with its substrate – the reactant being catalyzed
Substrate will only “fit” if shape of active site is a match
Once enzyme is done, it releases the product(s) and can be used over + over again
Mail fail to work if environment changes (temp or pH)

14. How an enzyme works…

15. Lipids Large, nonpolar organic molecules that do not dissolve in water
Higher ratio of C + H atoms to O atoms
C-H bonding (stores more nrg)

16. Lipids (cont.) Fatty acids – monomer of a lipid – unbranched chains
Contain a carboxyl group, -COOH, at one end
Hydrophilic end – attracted to water (polar)
Hydrocarbon at other end
Hydrophobic end – “afraid” of water (nonpolar)

17. Saturated vs. Unsaturated
Saturated – all C atoms are “full”
Unsaturated – has double bond(s) between C atoms

18. Lipids (cont.) Triglyceride – 3 fatty acid molecules + glycerol
Functions:
NRG, insulation + protection, nutrition (vitamins ares stored in fats in body)
Types:
Saturated
High melting point, room temp.
Examples: shortening (Crisco), animal fats
Unsaturated
Low melting point, room temp.
Examples: plant seed oils, fruits

19. Lipids (cont.) Phospholipids – 2 fatty acid molecules + glycerol
Forms lipid bilayer for cell membranes

20. Lipids (cont.) Wax – long fatty acid chain + long chain of alcohol
Highly waterproof
Used as a protective coating

21. Lipids (cont.)
Steroids – molecules of 4 fused C-rings with different functional groups
Common types:
Hormones – testosterone
Cholesterol – needed by nerves + cells

22. Nucleic Acids
Very large, complex organic molecules that store important information in cells
Two types:
DNA – deoxyribonucleic acid – determines characteristics of organism and directs cells activities
RNA – ribonucleic acid
Stores + transfers info. essential to make proteins
Can also act as an enzyme
Nucleotides – monomers of Nucleic Acid
5-C sugar
Phosphate group
Nitrogen-base

23. What a nucleotide looks like…

24. DNA vs. RNA