LIFE 102 1st EditionExam # 1 Study Guide Lectures: 1 – 9 (Ch. 1-6)Chapter One: Life’s uniformity is most evident at the chemical level, and it’s diversity most evident at the organism level.Chapter two: Atoms fill their valence shells (outer shell) with two strategies. Ionic bonds: where atoms eitherdonate or accept electrons to create a full shell. The cell that loses the electron becomes a cation (positively charged ion) and the one that gains the electron becomes an anion (negatively charged). Or, covalent bonds: atoms share an electron, and there are no polarized regions. There are also polar covalent bonds (see *1)Hydrogen, oxygen, nitrogen, and carbon (HONC) compose 96% of living matter. There are more essential elements though, such as Phosphorous (P) and Potassium (K). The number of atoms in an element has determines what element it is. For example, carbon has six protons; it will always have six protons. If it does not, it is no longer carbon. Isotopes are atoms of the same element that vary in atomic mass (protons + neutrons) becausethey have a different number of neutrons (neutrons weigh 1). For example carbon isotopes all have 6 protons (or else they wouldn’t be carbon) but vary in their number of neutrons, which can make their atomic mass 12, 13, or 14. Radioactive isotopes are very unstable. [*1] Electronegative elements have a stronger pull on electrons. Because of this, in covalent bonds the shared electrons spend more time near the more electronegative element, creating apolarized (charged) region of the molecule.When an atoms valence shell is not filled, they want to make bonds to become stable. Hydrogen makes 1 bond, oxygen makes 2, nitrogen makes 3 and carbon makes 4. (HONC1234)Hydrogen bonds are important because they can bond polar molecules. The positive region of the Hydrogen is attracted to the negative region of the more electronegative atom, for example the oxygen in a water molecule. The mass conservation law states that all atoms present in the reactants are still present in the products. In other words, matter can neither be created nor destroyed.When it is said that a reaction is reversible (which all reactions technically are) it means that it can go both ways. For example, photosynthesis is the reverse reaction of aerobic respiration. Chemical equilibrium is when the rate of the forward reaction is equal to the rate of the reversereaction. There is no change in the concentrations of the reactants, however remember that reactions are still taking place. Chapter three: There are for important properties of water:1) It is cohesive: the molecules “stick” to each other. This is why it has a high surface tension (measure of how hard it is to stretch/break the surface of a liquid). Think of certain animal or insects that can walk on water2) It moderates temperature: this is because of its high specific heat (the amount of energy required to raise 1 g of water 1 degree Celsius). In other words, water changes its temperature less than other liquids when it absorbs the same amount of energy. 3) It expands upon freezing: unlike other liquids, water is most dense at 4 degrees Celsius (not 0). When it freezes the hydrogen bond keep the molecules “at arms length” causing it to expand, making it LESS dense than liquid water. Therefore it floats! Water also has a high heat of vaporization, meaning it takes a LOT of energy to vaporize water. 4) It is an excellent solvent: Why? It forms hydrogen bonds easily, which can go in and bond with and break apart hydrophilic (water loving, which are ions or polar) molecules like NaCl. Hydrophobic (water fearing) like non-ionic or non-polar compounds, on the other hand, do not bond well will water.Concentration is how much solute is present per volume of solvent in moles. The solute is the substance being dissolved; the solvent is the dissolving agent of the solution. Acidity is the measure of how many H+ ions are in the solution. If the pH is less than 7, it’s acidic. pH= 7 it is neutral. pH is greater than 7, it is basic. The higher concentration of H+, the more acidic the solution is. Pure water has a pH of 7, meaning the concentration of H+ ions is 7.The formula is pH= -log [H+]A buffer is a substance that minimizes changes in the H+ and OH- in a solution. Usually it is an acid-base pair that reversibly combines with H+.Bases “mop” up the H+ ions by bonding with them, causing the acidity to go down. For example: NH3 + H+ NH4+ Another example: KOH + H+ K+ +H2OChapter four:An organic molecule is a molecule that includes Carbon. Carbon is a great building block for organic molecules because it is tetravalent (it needs to make 4 bonds) which leads to large, diverse and complex molecules.There can be variations in the carbon skeleton: Length, Branching, Double bond position, and Presence of rings. For example, butane and isobutene have the same atomic composition, but isobutane has a branched skeleton. Side groups have different functional properties:Hydroxyl: polar Carbonyl: PolarCarboxyl: acid Amino: baseSulfhydryl: binds to other sulfydryl groupsPhosphate: polar, reactive Methyl: non-polarCarboxyl groups can function as an acid: it can donate H+ because the covalent bond between oxygen and hydrogen is so polar. Amino groups can function as a base because it can pick up anH+ from the surrounding solution (which is water in living organisms).An Isomer is a molecule with the same atomic composition but different structures (and therefore different properties) Structural Isomer: variation in carbon skeleton. For example butane and isobutane. Cis-trans isomer: variation in arrangement of side groups around a double bond. Enantiomers: mirror like images of the same atomic composition. Like left and right hands. Chapter five: Triose, pentose and hexose sugars are considered Aldoses. Glucose is a monosaccharide.A disaccharide is two sugar monomers linked together. Polysaccharides (many sugars) serve as fuel and building material. For example: starch is storedplant energy, cellulose serves as structure for plants and chitin serves as structure of animals.Lipids are included in chapter five, however, they are not polymers. They are not as big, and they are Hydrophobic. They can either be fats, phospholipids or steroids.Fats (triglycerides) are composed of glycerol + 3 fatty acids, which are attached by dehydration synthesis. They are