bio 1201 midterm QUESTIONS AND ANSWERS

bio 1201 midterm QUESTIONS AND ANSWERS Selective Permeability What the plasma membrane exhibits, which allows some substances to cross the plasma membrane more easily than others. Amphipathic A molecule that has both a hydrophobic and hydrophilic region. Metabolism the totality of an organism's chemical reactions metabolic pathway Fermentation a partial degradation of sugars or other organic fuel that occurs without the use of oxygen Aerobic respiration oxygen is consumed as a reactant along with the organic fuel Cellular respiration includes both aerobic and anaerobic processes. ( Organic compounds + Oxygen - carbon dioxide + Water + Energy Redox reactions a transfer of one or more electrons from one reactant to another (oxidation-reduction reactions) Oxidation the loss of electrons from one substance Reduction the addition of electrons to another substance Reducing agent the electron donor Oxidizing agent the electron acceptor Electron transport chain used to break the fall of electrons to oxygen into several energy releasing steps, consists of a number of molecules, mostly proteins built into the inner membrane of the mitochondria of eukaryotic cells Glycolysis catabolic pathway that breaks down glucose and other organic fuels, begins degradation process by breaking glucose into two molecules of a compound called pyruvate in eukaryotes, pyruvate enters the mitochondrion and is oxidized to a compound called acetyl CoA, which enters the citric acid cycle Citric acid cycle the breakdown of glucose to carbon dioxide. Oxidative phosphorylation the energy released at each step of the chain is stored in a form the mitochondrion can use to make ATP from ADP. Substrate-level phosphorylation a smaller amount of ATP is formed directly in a few reactions of glycolysis and the citric acid cycle. Acetyl CoA upon entering the mitochondrion via active transport, pyruvate is the first converted to a compound called acetyl coenzyme. Cytochromes proteins that are remaining electron carriers between ubiquinone and oxygen are proteins ATP synthase enzyme that makes ATP from ADP and inorganic phosphate Chemiosmosis energy stored in the form of a hydrogen ion gradient across a membrane is used to drive cellular work such as the synthesis of ATP Proton-motive force H+ gradient that results Alcohol fermentation pyruvate is converted to ethanol in two steps Obligate anaerobes carry out only fermentation or anaerobic respiration Facultative anaerobes organisms m including yeasts and many bacteria, can make enough ATP to survive using either fermentation or respiration Beta oxidation a metabolic sequence that breaks the fatty acids down to two carbon fragments, which enter the citric acid cycle as acetyl CoA. Which of the following is likely to lead to an increase in the concentration of ATP in a cell? an increase in a cell's catabolic activity Which of the following is an example of potential rather than kinetic energy? Electrons in a protein When glucose monomers are joined together by glycosidic linkages to form a cellulose polymer, the changes in free energy, total energy, and entropy are as follows: +△G, +△H, -△S Which is least stable A) CO2 B) H2O. C) Glucose *D) Saturated fat When Glutamic acid is phosphorylated by ATP, what happens? Glutamic acid becomes more reactive What would happen if enzymes did not mediate catabolic, exergonic reactions of large molecules in organisms? All their energy would be lost as heat During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a △G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the △G for the new reaction? -20 kcal/mol Which of the following metabolic processes can occur without a net influx of energy from some other process? C6H12O6 + 6 O2 −− 6 CO2 + 6 H2O What does this figure show? Allosteric regulation of an enzyme The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as feedback inhibition.