Chapter 2: The Chemical Basis of Life Matter is anything that has mass & takes up space. Solid Liquid Gas Elements make up all matter (living and nonliving). EX. Carbon, oxygen, hydrogen

Basic Chemistry (carbon, hydrogen, nitrogen, oxygen) There are only 25 elements that are basic to life. CHON= Make up 96% human weight (carbon, hydrogen, nitrogen, oxygen) The atom is the smallest part of an element. Made up of: 1) protons (+ charge) 2) neutrons (neutral) 3) electrons (- charge)

Basic Chemistry cont. Atomic Number: the number of protons in the nucleus of atom that makes it unique. Atomic Mass = # of protons + # of neutrons

Basic Chemistry cont. Isotopes = same # protons, different # of neutrons Radioactive isotopes release energy in the forms of rays & subatomic particles. Can harm cells Damage DNA Cause cancer May have beneficial uses: Sterilize medical equipment Kill cancer cells

Chemistry of Life Bonds: Ionic: oppositely charged ions are attracted to each other after gaining or losing electrons Water soluble (ionic bonds break) Ex. NaCl table salt Covalent: atoms share valence electrons Bonds do not break in water; often not water soluble Ex. C6H12O6 glucose Polar covalent: atoms share valence electrons unequally A prerequisite for hydrogen bonds Hydrogen: partially positive H (part of a polar covalent bond) is weakly attracted to partially negative O, N, or F (part of polar covalent bond) Ex. H20 water 5

Water’s Life Supporting Properties Water is cohesive & adhesive Cohesion: water molecules stick together Hydrogen has partial positive charge Oxygen has partial negative charge Oxygen of one H2O molecule attracted to Hydrogen of another molecule Adhesion: water is attracted to other partially charged substances Surface Tension: a measure of how difficult it is to stretch or break the surface of a liquid

Water’s Life Supporting Properties Heat: the amount of energy associated with the movement of atoms and molecules Temperature: measures average speed of molecules Ice is less dense than liquid water due to the 3-D crystalline bonding pattern Hydrogen bonds are stable Atoms are equally spaced apart Hydrogen bonds in liquid water constantly break & re-form

Water’s Life Supporting Properties Solution: liquid consisting of a uniform mixture of 2 or more substances Solvent: dissolving agent Solute: Substance that is dissolved Aqueous solution: water is the solvent Water can dissolve ionic compounds & other polar molecules (Ex. NaCl, sugar)

Chemistry of Life pH (Power of Hydrogen ions) Scale from 1 (highest # of H+) to 14 (lowest # of H+) Low numbers are acids (1-6) High numbers are bases (8-14) 7 is neutral

Chemistry of Life All living things contain carbon. Organic compounds are substances that contain carbon and make up all living things. There are four kinds of organic compounds: 1) carbohydrates 2) lipids 3) proteins 4) nucleic acids

Organic Compounds Carbohydrates Sugars & starches Contain elements C, H, O in a 1:2:1 ratio C6H12O6 glucose Energy source for living things The building blocks of carbohydrates are monosaccharides or single sugars. Dissacharides are two single sugars bonded together. Ex. Sucrose (table sugar)= glucose + fructose Polysaccharides are 3 or more single sugars bonded together. Ex. Starch, cellulose, glycogen

Organic Compounds The building blocks of lipids are fatty acids. Fats, waxes, and oils Do not dissolve in water Made up of C, H, and O but not in a ratio Store and release energy Ex. Steroids, phospholipids, chlorophyll The building blocks of lipids are fatty acids.

Organic Compounds Proteins Made up of the elements C, H, O, N, S Make up hair, skin, nails The building blocks of proteins are amino acids. Enzymes are special proteins that speed up chemical reactions. Ex. Salivary amylase

Organic Compounds The building blocks of nucleic acids are Ex. DNA & RNA DNA is found in the nucleus of all living cells. DNA makes up genes which store hereditary information. The building blocks of nucleic acids are nucleotides. Nucleotides are made up of 3 parts: 1) a base 2) a sugar 3) a phosphate

ATP Adenosine triphosphate (ATP) is an energy found in living cells. Fuel for cells Used to make proteins & carbohydrates in cell Energy needed for muscle cells to contract Energy needed for nerve cells to conduct impulses ATP stores its energy in the chemical bonds between the phosphate atoms. Energy is released when bonds are broken. ATP is made up of a sugar, the base adenine, and 3 phosphate molecules.