Life 102 (003): Attributes of Living SystemsStudy Guide Exam 2DEFINITIONSPhospholipids bilayer: A lipid made up of glycerol joined by two fatty acids and a phosphate group. The hydrocarbon chains of the fatty acids as nonpolar, hydrophobic tails,while the rest of the molecule acts as a polar, hydrophilic head. Phospholipids form bilayers that function as biological membranes.Peripheral membrane protein: A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer.Passive transport: The diffusion of a substance across a biological membrane with no expenditure of energy.Exocytosis: The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane.Feedback inhibition: A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.Oxidation: The loss of electrons from a substance involved in a redox reaction.Exergonic reaction: A spontaneous chemical reaction, in which there is a net release of free energy.Redox reaction: A chemical reaction involving the complete or partial transfer of one or more electrons form one reactant to another; short of oxidation-reduction reaction.Citric acid cycle: A chemical cycle involving eight steps that completes the metabolic breakdown of glucose molecules begun in glycolysis by oxidizing pyruvate to carbon dioxide; occurs within the mitochondrion in eukaryotic cells and in the cytosol of prokaryotes; the second major stage in cellular respiration.Acetyl-CoA: Acetyl coenzyme A; the entry compound for the citric acid cycle in cellular respiration, formed from a fragment of pyruvate attached to a coenzyme.Light reactions: The first of two major stages in photosynthesis (preceding the Calvin cycle). These reactions, which occur on the thylakoid membranes of the chloroplast or on membranes of certain prokaryotes, convert solar energy to the chemical energy of ATP and NADPH, releasing oxygen in the process.Stoma: A microscopic pore surrounded by guard cells in the epidermis of leaves and stemsthat allows gas exchange between the environment and the interior of the plant.Photon: A quantum, or discrete quantity, of light energy that behaves as if it were a particle.Enzyme: A macromolecule serving as a catalyst, a chemical agent that changes the rate of areaction without being consumed by the reaction.Non-competitive inhibitor: A substance that reduces the activity of an enzyme by bindingto a location remote from the active site, changing the enzyme’s shape so that the active site no longer functions effectively.Anaerobic metabolism: (Anaerobic respiration) The use of inorganic molecules other than oxygen to accept electrons at the “downhill” end of electron transport chains.Reduction: The addition of electrons to a substance involved in a redox reaction.Diffusion: The spontaneous movement of a substance down its concentration gradient, from a region where it is more concentrated to a region where it is less concentrated.Osmosis: The diffusion of water across a selectively permeable membrane.Active transport: The movement of a substance across a cell membrane, with an expenditure of energy, against its concentration or electrochemical gradient; mediated by specific transport proteins.Catabolic metabolism: (Catabolic pathway) A metabolic pathway that releases energy by breaking down complex molecules to simpler compounds.Anabolism: (Anabolic pathway) A metabolic pathway that consumes energy to synthesize a complex molecule from simpler compounds.Endergonic: (Endergonic reaction) A nonspontaneous chemical reaction, in which fee energy is absorbed from the surroundings.Respiration: (Cellular respiration) The catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules for the production of ATPReduction: The addition of electrons to a substance involved in a redox reaction.Electron transport chain: A sequence of electron carrier molecules (membrane proteins) that shuttle electrons during the redox reactions that release energy used to make ATP.Pyruvate: Photosynthesis: The conversion of light energy to chemical energy that is stored in sugarsor other organic compounds; occurs in plants, algae, and certain prokaryotes.Calvin cycle: The second of two major stages in photosynthesis (following light reactions),involving fixation of atmospheric CO2 and reduction of the fixed carbon into carbohydrate.Chlorophyll: A green pigment located within the chloroplasts of plants and algae and in the membranes of certain prokaryotes. Chlorophyll a participates directly in the light reactions, which convert solar energy to chemical energy.Activation energy: The amount of energy that reactants must absorb before a chemical reaction will start; also called free energy of activation.Enzyme co-factor: Electronegative: The attraction of a given atom for the electrons of a covalent bond.Integral membrane protein: Typically a transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane w=and with hydrophilic regions in contact with the aqueous solution on wither side of the membrane (or lining the channel in the case of a channel protein).Endocytosis: Cellular uptake of biological molecules and particulate matter via formation of new vesicles from the plasma membrane.Gibbs free energy: The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system. (The change in free energy of a system is calculated by the equation Delta G = Delta H – T Delta S, where H is enthalpy [in biological terms, equivalent to total energy], T is absolute temperature, and S is entropy).Active site: The specific portion of an enzyme that binds the substrate by means of multiple weak interactions and that forms the pocket in which catalysis occurs.Glycolysis: The splitting of glucose into pyruvate. Glycolysis occurs in almost all living cells, serving as the starting point for fermentation or cellular respiration.Chapter 7: Membranes1. What are the functions of membranes? What are the major structural components of membranes? Semi-permeable (allow some materials to pass through while keeping others out). Proteins, phospholipid bilayer. 2. The plasma membrane is a selectively-permeable membrane. What does that