Unit 2: Biochemistry HIGHLIGHTS What you should know…

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

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

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.

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

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.

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)

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.

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.

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

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

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

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

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

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.