1. The Molecules of Cells
Chapter Three

2. Classes of Compounds Inorganic compounds Organic compounds
Water, salts, and many acids and bases
Do not contain carbon
Organic compounds
Carbohydrates, fats, proteins, nucleic acids
Contain carbon, usually large, covalently bonded
Life’s molecular diversity is based on the properties of carbon

3. Macromolecules
There are four important macromolecules (organic compounds) in the body: Carbohydrates, Lipids, Proteins, Nucleic acids
Three of these macromolecules are Polymers
Polymers = chain-like molecules consisting of many similar/identical building blocks (monomers)
Linked by covalent bonds
Organic compounds that are Polymers = Carbohydrates, Proteins, Nucleic acids

4. Cells Make and Break Polymers Using Two Main Types of Chemical Reactions
Dehydration (synthesis) reactions: Monomers are linked together to form polymers and a molecule of water is lost
Each monomer contributes part of the H2O molecule that is lost

5. Cells Make and Break Polymers Using Two Main Types of Chemical Reactions
Hydrolysis reactions: Polymers are broken down into monomers by the addition of water molecules
reverse of the dehydration synthesis reactions

6. Carbohydrates Functions Contain C, H, and O
Polymers of monosaccharides
Three classes
Monosaccharides -Simple sugars containing three to seven C atoms
Ex. Glucose
Disaccharides -Double sugars
fructose, sucrose, maltose
Polysaccharides –many monosaccharides linked together ex., starch, glycogen, cellulose
Functions
Cellular fuel
Provide structure in RNA and DNA

7. Carbohydrates: Polysaccharides

8. Lipids Contain C, H, O and sometimes P Mainly insoluble in water
Several Classes of Lipids
Triglycerides
Phospholipids
Steroids

9. Triglycerides Triglycerides—solid fats and liquid oils
Three fatty acids bound to glycerol (3:1)
Functions
Energy storage
Insulation
Protection

10. Phospholipids Similar to triglycerides
Two fatty acids bound to glycerol (2:1), bound to a phosphate group
“Head” and “tail” regions have different properties
Main component of cellular membranes

11. Steroids Composed of four fused carbon rings
Ex’s. Cholesterol, vitamin D, steroid hormones, and bile salts

12. Proteins Contain C, H, O, N, and sometimes S Polymers of amino acids
All 20 amino acids have same basic structure
Amino acids are held together by peptide bonds (polypeptides)

13. Denaturing Natural Folding
(protein folding animation 2m 19 s) start around 1:11

14. Nucleic Acids Two examples: DNA and RNA Contain C, O, H, N, and P
Polymers of nucleotides: nucleotides have 3 parts: a N-containing base, a pentose sugar, and a phosphate group

15. Deoxyribonucleic Acid (DNA)
Four bases:
adenine (A), guanine (G), cytosine (C), and thymine (T)
Double-stranded, helical
Replicates before cell division, ensuring genetic continuity
Provides instructions for protein synthesis

16. Ribonucleic Acid (RNA)
Four bases:
adenine (A), guanine (G), cytosine (C), and uracil (U)
Uracil replaces thymine in RNA
Single-stranded
Mainly active outside of nucleus