Chemistry of Life Unit When water, H2O, is created, hydrogen and oxygen share the electrons The oxygen has a slightly negative charge The hydrogen’s have a slightly positive charge This uneven pattern of charge creates a polar molecule = has a positive side and negative side

Water Molecule

Hydrogen Bonding Hydrogen Bond = an attraction between a slightly positive hydrogen atom and a slightly negative atom, often oxygen or nitrogen

Hydrogen Bonding

Properties Related to Hydrogen Bonding Life depends on hydrogen bonds in water High Specific Heat = water resists changes in temp. - helps regulate cells

Properties Related to Hydrogen Bonding (cont) Cohesion = attractive forces between particles of the same kind - example: surface tension of water

Surface Tension

Surface Tension – Floating Paper Clips

Catching Fleas with Soapy Water

Properties Related to Hydrogen Bonding (cont) Adhesion = the attractive forces between unlike substances - example: meniscus curve in a graduated cylinder

Meniscus Curve

Properties Related to Hydrogen Bonding (cont) Capillarity = the ability of water to move up through narrow tubes against gravity - due to cohesion and adhesion - example: carnations turning a different color in colored water

Carnations in Colored Water

Solutions The polarity of water makes it very effective at dissolving many substances Solvent + Solute = Solution Concentration [ ] = amount of solute in a given amount of solvent Saturated = no more solute will dissolve in the solvent

Solvent + Solute = Solution

Mosquito injects a solution into your body that prevents clotting

Solutions (cont) Water is the universal solvent. All processes necessary for life take place in water.

Acids and Bases Acid = compound that releases a hydrogen ion (H+) when dissolved in water - increases the H+ [ ] Base = compound that remove H+ ions from a solution - lowers the H+ [ ]

Acids and Bases (cont) pH scale = amount of H+ ions in a solution 0 to 6 = acidic 7 = neutral 8 to 14 = basic buffer = compound that regulates H+ [ ] - maintains homeostasis

pH Scale

Car Analogy for Organic Compounds Toyota Camry Toyota Supra

Organic Compounds Carbon is the building block of life - can form multiple bonds (up to 4), including other carbon atoms More than 90 % of the mass of all living things are composed of combinations of just 4 elements 1) Carbon ( C) 2) Hydrogen (H) 3) Oxygen (O) 4) Nitrogen (N)

1) Carbohydrates Examples sugars starches cellulose glycogen Specifics - contain C, H, and O - main source of usable chemical energy for cells - major part of plant cell wall (made of cellulose) - most basic are simple sugars = monosaccharides (glucose) - bond to form polysaccharides

1) Carbohydrates

Field of Cotton

2) Lipids Examples Fats Oils Cholesterol Specifics - contain C, H, and O - store large amounts of energy - cell membrane made up of phospholipids - regulate body responses and control sexual development - are nonpolar molecules (don’t dissolve in water)

Saturated Fats (solid at room temp)

Unsaturated Fats (liquid at room temp)

3) Proteins Examples Specifics - contain C, H, O, and N - made of monomers called amino acids - 20 different amino acids build proteins - specific sequence determines structure and function

Red Blood Cells and Sickle Cell Anemia (SEM 3500x)

4) Nucleic Acids - work together to make proteins Functions: – stores info to build proteins – helps build proteins Types: 1) DNA 2) RNA

Chemical Reactions = change substances into different substances by breaking and forming chemical bonds

6O 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O 1. Reactants = substances changed during a chemical reaction (left side) 2. Direction 3. Products = substances made during a chemical reaction (right side)

* Chemical reactions release or absorb energy

Types of Chemical Reactions Activation Energy = the amount of energy needed to start a reaction - is very high in most chemical reactions (especially in the body)

Activation Energy

Types of Chemical Reactions (cont) Exothermic = chemical reaction that releases more energy than it absorbs - gives off heat (hot) - ex: cellular respiration

Exothermic Reaction

Glowsticks

Bioluminescence

Types of Chemical Reactions (cont) Endothermic = chemical reaction that absorbs more energy than it releases - absorbs heat (cold) - ex: photosynthesis

Endothermic Reaction

Cold packs

Exothermic ReactionEndothermic Reaction

Enzymes Catalyst = substance that reduces the amount of activation energy that is needed to start a chemical reaction Catalysts are not changed during a chemical reaction Enzymes = a type of catalyst in living things

Enzymes (cont) - almost all are proteins - work best in normal body conditions (temp. and pH) - specific shape allows only certain reactants to bind - fit like a lock and key

Lock and Key Model - Enzymes

Enzymes (cont) - functions: 1) help bring substrates together and chemical reactions occur 2) decrease the activation energy of the reaction 3) increase the rate of the reaction

Enzymes reduce Activation Energy

Enzymes (cont) - Reaction 1 requires more activation energy than Reaction 2 - Reaction 3 has less activation energy due to a catalyst being used

Enzymes in Your Life