1. Unit 2: Biochemistry HIGHLIGHTS
What you should know…

2. Water
H2O
Polar molecule – unequal, partial charges make it slightly unbalanced
Like dissolves like – polar molecules will only mix with other polar molecules, but not nonpolar ones.
Nonpolar = oil-based substances

3. Water is Important to Life
Surface tension: adhesion (water molecules stick to surfaces) and cohesion (water molecules stick to each other)
High heat capacity: water can absorb and release a lot of energy before changing temperature
Density properties: ice floats on water
Solvent of life: most things dissolve in water

4. Mixtures with Water Homogenous mixtures are solutions.
Solute: substance being dissolved, like sugar or salt
Solvent: substance dissolving, usually water
Heterogenous mixtures have particles in them that will settle, like Italian dressing, blood, and a sand/water mixture.

5. pH Acids: release H+ ions in water Bases: release OH- ions in water
pH 1 – 6, positive charge, taste sour, sticky feel
Bases: release OH- ions in water
pH 8 – 14, negative charge, taste bitter, slimy feel
Neutral
pH 7, no charge, salts
Buffers: chemicals that prevent pH from changing too drastically – stabilize pH
Buffers keep your blood at pH 7.35 – 7.45

6. Organic Macromolecules
Organic: contains lots of carbon – hydrogen bonds (glucose – C6H12O6)
Inorganic: usually do not have carbon – hydrogen bonds (CO2, CaCl, etc.)
Macromolecules: large molecules called polymers made up of smaller building blocks called monomers
Chemical bonds in these molecules store energy to do work.

7. Macromolecules Carbohydrates: carbon, hydrogen, oxygen
Monomer: glucose
Simple sugars, called monosaccharides, serve as the main source of energy for the cell. Example: glucose
Complex carbohydrates, called polysaccharides, serve as short-term energy storage (starch in plants, glycogen in animals), help build plant cell walls (cellulose), and help build exoskeletons of insects (chitin)

8. Macromolecules
Proteins: carbon, hydrogen, oxygen, nitrogen, sometimes sulfur
Monomer: amino acids
Fibrous proteins are used in the structure of cells and organisms, like building the cytoskeleton and your muscles.
Globular proteins help in transporting molecules within and between cells, and regulating chemical reactions of the body (enzymes).
Proteins are only used for energy if all carbohydrates and lipids are gone, but in excess, it can be dangerous.

9. Macromolecules Lipids: carbon, hydrogen, oxygen
Monomer: triglycerides (glycerol and fatty acids)
Contain more C – H bonds than carbohydrates.
True fats include saturated and unsaturated fats, and are used as long-term energy storage. They are also used to insulate our organs and help with shock absorption.
Phospholipids are a major component of cell membranes.
Steroids are used in making some vitamins and hormones.

10. Chemical Reactions
Chemical bonds break and reform, and atoms are rearranged.
Chemical bonds
Ionic bonds: electrons are traded between atoms
Covalent bonds: electrons are shared between atoms
Hydrogen bonds: polar covalent molecules (like water) are attracted to opposite partial charges
Adhesion and cohesion

11. Chemical Reactions Structure: reactant + reactant  product
Bond energy: amount of energy it takes to break a chemical bond; different between different atoms
Activation energy: amount of energy needing to be absorbed for a chemical reaction to start
Chemical reactions absorb or release energy.
Exothermic reaction: releases energy as heat or light; breaks down substances
Endothermic reaction: absorbs energy; builds substances

12. Chemical Equilibrium
A reversible reaction moves in both directions at equal rates.
Reactants and products are being made at the same rate.
Ex: H2O + O   H2O2

13. Enzymes
Biological catalysts that speed chemical reactions up in living things
Made of proteins
Lowers the activation energy of a reaction so that reaction will happen faster
Used over and over again without being altered

14. Enzymes
Very specific – one type of enzyme only fits with one type of substrate
Substrate = reactant that binds to enzyme; it is converted into a product in the chemical reaction
Substrate binds at the active site – these fit together like puzzle pieces
An enzyme’s structure can be altered by high temperature and extreme pH (low and high)
Denaturation: unfolding of a protein due to extreme conditions; will not function properly

15. Biochemical Reactions
Enzymes are involved in reactions necessary for organisms to live, reproduce, and grow.
A biochemical pathway consists of several enzymes in a row:
Enzyme 1  product A  enzyme 2  product B  enzyme 3  product C
Biochemical reactions are affected by chemical reactions, changes in temperature and pH, and enzymes.