Chemistry of Life 

I. Some Basic Chemistry

A. Living organisms are chemical systems

Ecosystem - organism - organ system - organ - tissue - cell - organelles - molecules

B. All matter consists of atoms (elements)

C. Atoms can be found in various forms

1. Elemental
2. Compounds
3. Ions
4. Isotopes

D. Living cells consist of at least 25 essential elements

1. Structural elements: C H O P N S
2. Micronutrients: Ca K Na Cl Mg
3. Trace elements: Fe, Cu, F, I, .....

E. Atoms are joined together by chemical bonds to form molecules

1. Ionic bonds
2. Covalent bonds

F. Chemicals undergo changes (reactions) due to the breaking and reforming of bonds

1. Reactants
2. Products
3. Catalysts
4. Enzymes

G. Water has unique chemical properties that make it able to support life

1. Cohesion
2. Adhesion
3. Surface tension
4. Heat capacity
5. Solvent
6. Ice
7. pH

H. Chemical solutions consist of solvents and solutes 

II. Biologically important types of molecules

A. Carbohydrates

Basic chemical formula: (CH₂O)_n

1. Monosaccharides - glucose, fructose, galactose, ribose

2. Disaccharides - sucrose, lactose, maltose, cellobiose

3. Polysaccharides - starch, glycogen, cellulose, chitin

B. Proteins

Basic chemical formula: H₂N - HCR - COOH

1. Amino acids

2. Dipeptides - 2 amino acids joined by a peptide bond

3. Oligopeptides - short chains of amino acids

4. Proteins - chains of generally > 100 amino acids

C. Lipids

1. Steroids - cholesterol, testosterone, estrogen

2. Fatty acids - linoleic acid

• Basic chemical formula: CH₃ - (CH₂)_n - COOH

3. Triglycerides - glycerol + 3 fatty acids

4. Phospholipids - glycerol + 2 fatty acids + phosphate

D. Nucleic Acids

1. DNA - chains of nucleotides

• Nucleotides = deoxyribose + phosphate + nitrogen base

2. RNA - ribose + phosphate + nitrogen base