grade 12 AP biology exam notes

Biochemistry

Essential Elements of Life
Carbon, hydrogen, oxygen, nitrogen (96%)
Calcium, phosphorus, potassium, sulphur (4%)

Isotopes
Atoms of an element that differ in neutrons
Radioactive isotopes decay spontaneously, giving off energy

Cohesion
Hydrogen bonds hold water molecules together
Adhesion is an attraction between two substances
Surface tension measures how hard it is to break the surface tension of a liquid

Hydrocarbons
Organic molecules consisting of only carbon and hydrogen

Isomers
Structural
Have different covalent arrangements of the atoms
Geometrical
Same covalent arrangement but different spatial arrangements
Enantiomers
Mirror images of each other

Functional Groups
Hydroxyl
OH
Carbonyl
C=O
Carboxyl
OH-C=O
Amino
NH2
Sulfhydryl
SH
Phosphate
O3-P=O
Methyl
CH3

Macromolecules
Needed in large quantities
Polymers
Carbohydrates
Lipids
Proteins
Nucleic Acids
Three of the four molecules are polymers
Carbohydrates
Proteins
Nucleic Acids

Carbohydrates
Include sugars
Simplest carbs are monosaccharide’s
Usually multiples of CH2O
Glucose is the most common monosaccharide

Polysaccharides
The polymers of sugars having storage and structural roles
Starch is a polysaccharides of plants’ storage
Glycogen is the storage for animals
Cellulose is the cell wall of plants structure
Chitin is a structural polysaccharide in arthropods

Lipids
Do not for polymers
Hydrophobic because consist of mostly hydrocarbons
Most important lipids are fats, phospholipids and steroids

Fats
Made up of glycerol and fatty acids
Glycerol is a 3 carbon alcohol with a hydroxyl group
A fatty acid consists of carboxyl group attached to a long carbon skeleton
Saturated have as many hydrogen’s as possible with no double bonds
Unsaturated have one or more double bonds

Phospholipids
2 fatty acids and a phosphate group attached to a glycerol
The 2 tails are hydrophobic but have a