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Bio Chapters 6,7,8
| Term | Definition |
|---|---|
| metabolism | totality of an organism's chemical reactions |
| metabolic pathway | a specific molecule is altered in a series of defined steps, resulting in a product |
| catabolic pathways | metabolic pathways that release energy by breaking down complex molecules to similar compounds (breakdown pathways) |
| anabolic pathways | consume energy to build complicated molecules from simpler molecules (biosynthetic pathways) |
| bioenergetics | study of how energy flows through living organisms |
| energy | capacity to cause change |
| kinetic energy | energy associated with relative motion of objects |
| thermal energy | kinetic energy associated with random movement of atoms and molecules |
| heat | thermal energy in transfer from one object to another |
| potential energy | energy matter possesses based on location and structure |
| chemical energy | potential energy available for release in a chemical reaction |
| thermodynamics | the study of the energy transformations that occur in a collection of matter |
| first law of thermodynamics | energy of the universe is constant (energy can be transferred and/or transformed, but it cannot be created or destroyed) |
| entropy | measure of disorder/randomness; more randomly arranged matter; greater entropy |
| second law of thermodynamics | every energy transfer or transformation increases the entropy of the universe |
| spontaneous process | process not requiring an input of energy if it leads to entropy's increase on its own (energetically favorable) |
| free energy | portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system |
| exergonic reaction | net release of free energy |
| endergonic reaction | absorbs free energy from its surroundings |
| energy coupling | use of an exergonic process to drive an endergonic one |
| ATP (adenosine triphosphate) | contains the sugar ribose, with nitrogenous base adenine and a chain of three phosphate groups |
| phosphorylated intermediate | recipient of phosphate group covalently bonded from ATP; more reactive than unphosphorylated molecule |
| enzyme | macromolecule that acts as a catalyst |
| catalyst | chemical agent that speeds up a reaction without being consumed by the reaction |
| activation energy (EA) | free energy of activation; initial investment of energy for starting a reaction which will contort reactant molecules to break their bonds |
| catalysis | when a catalyst selectively speeds up a reaction; lowers activation barrier without affecting triangleG |
| substrate | a reactant an enzyme acts on |
| enzyme substrate complex | when an enzyme binds to a substrate to convert the substrate to its products |
| active site | the restricted region of the enzyme molecule that binds to the substrate |
| induced fit | tightening a binding between enzyme and substrate after initial contact |
| cofactors | nonproteins that help enzymes in catalytic activity by binding tightly and permanently to the enzyme or loosely and reversibly with the substrate |
| coenzyme | cofactors that are organic molecules |
| competitive inhibitors | reduce enzyme productivity by blocking substrates from entering active sites; can be overcome by increasing the substrate concentration |
| noncompetitive inhibitors | bind to another part of the enzyme, forcing the enzyme to change its shape so even if the substrate binds, the enzyme will be less effective |
| allosteric regulation | when a protein's function at one site is affected by the binding of a regulatory molecule to a separate site |
| cooperativity | when one substrate binds to an active site and triggers shape change in all subunits, increasing catalytic activity at all other active sites |
| feedback inhibition | when a metabolic pathway is stopped by the inhibitory binding of its end product to an enzyme that acts early in the pathway |
| fermentation | a partial degradation of sugars or other organic fuel without using oxygen |
| aerobic respiration | oxygen is consumed as a reactant along with the organic fuel; most efficient process |
| cellular respiration | refers to anaerobic and aerobic respiration, but will more commonly mean aerobic respiration |
| redox reactions | oxidation-reduction reactions, where one or more electrons transfer from one reactant to another in chemical reactions |
| oxidation | loss of electrons from one substance in a redox reaction |
| reduction | addition of electrons to another substance in a redox reaction |
| reducing agent | the electron donor in a redox reaction |
| oxidizing agent | the electron acceptor in a redox reaction |
| NAD+ | nicotinamide adenine dinucleotide, a coenzyme that carries electrons (hydrogen atoms) to oxygen after having been removed |
| electron transport chain | mostly proteins built into the mitochondria's inner membrane where electrons are moved along the chain from NADH to O2 |
| glycolysis | starts in cytosol, breaks down glucose into two molecules of pyruvate |
| citric acid cycle | Krebs cycle, completes breakdown of glucose into carbon dioxide |
| oxidative phosphorylation | ATP synthesis powered by redox reactions of the electron transport chain |
| substrate-level phosphorylation | form of ATP synthesis where a phosphate group is transferred directly to ADP from an organic substrate by an enzyme |
| acetyl CoA | a highly reactive compound formed from pyruvate once CO2 has been removed |
| cytochromes | proteins between ubiquinone (Q) and O2 |
| ATP synthase | an enzyme in mitochondrion cristae that makes ATP from ADP and inorganic phosphate |
| chemiosmosis | where energy stored in the form of a hydrogen ion gradient across a membrane is used to drive cellular work, including the synthesis of ATP |
| proton-motive force | H+ gradient, emphasizing gradient's capacity to perform work |
| alcohol fermentation | pyruvate is converted to ethanol by releasing CO2 from pyruvate and converted to acetaldehyde (2-carbon compound) then acetaldehyde is reduced by NADH to ethanol |
| lactic acid fermentation | pyruvate reduced directly by NADH to form lactate, no release of CO2 |
| obligate anaerobes | organisms that only carry out fermentation or anaerobic respiration; can't survive in presence of oxygen |
| facultative anaerobes | organisms that make enough ATP to survive either with fermentation or respiration |
| beta oxidation | a metabolic sequence that breaks the fatty acids down to 2-carbon fragments which enter the citric acid cycle as acetyl CoA |
| photosynthesis | the process in which chloroplasts capture light energy from the sun and convert it into chemical energy stored in organic molecules |
| autotrophs | sustain themselves without eating anything derived from other living beings; "self-feeders" or producers |
| heterotrophs | can't make their own food so live on compounds produced by other organisms; consumers or "other feeders" |
| mesophyll | where most chloroplasts are found; tissue in the leaf's interior |
| stomata | microscopic pores where carbon dioxide enters and oxygen exits |
| stroma | dense fluid surrounded by two membranes of chloroplasts |
| thylakoids | third membrane system composed of sacs that keep the stroma from touching the thylakoid space within the sacs |
| chlorophyll | green pigment that gives leaves their color, within thylakoid membranes |
| light reactions | photo part of photosynthesis |
| Calvin cycle | synthesis part of photosynthesis |
| NADP+ | nicotinamide adenine dinucleotide phosphate; temporarily stores electrons and H+ after light energy splits them from water |
| NADPH | when a pair of electrons and an H+ are added to NADP+ by light energy |
| photophosphorylation | when chemiosmosis powers the addition of a phosphate group to ADP to make ATP |
| carbon fixation | incorporation of CO2 into organic molecules in the chloroplast; beginning of the Calvin cycle |
| wavelength | distance between crests of electromagnetic waves |
| electromagnetic spectrum | range of radiation |
| photons | discrete particles making up light; each one has a fixed quantity of energy |
| spectrophotometer | instrument that measures a pigment's ability to absorb wavelengths |
| absorption spectrum | a graph plotting a pigment's light absorption versus wavelength |
| chlorophyll a | key light-capturing pigment that participates directly in light reactions |
| chlorophyll b | accessory pigment |
| action spectrum | profiles the relative effectiveness of different wavelengths of radiation in driving the process |
| carotenoids | accessory pigments that are hydrocarbons absorbing violet and blue-green light |
| photosystem | composed of a reaction-center complex surrounded by several light-harvesting complexes |
| reaction-center complex | organized association of proteins holding a special pair of chlorophyll a molecules |
| light-harvesting complex | composed of various pigment molecules (including chlorophyll a, chlorophyll b, and carotenoids) bound to proteins |
| primary electron acceptor | molecule in the reaction-center complex capable of accepting electrons and being reduced |
| photosystem 2 (PS 2) | 680nm; in the thylakoid membrane; cooperates in light reactions of photosynthesis |
| photosystem 1 (PS 1) | 700nm; in the thylakoid membrane; cooperates in light reactions of photosynthesis |
| linear electron flow | energy is transferred through the photosystem, beginning ATP and NADPH synthesis, by passing electrons along the photosystems |
| glyceraldehyde 3-phosphate (G3P) | a 3-carbon sugar produced by the Calvin cycle; the Calvin cycle does not directly produce glucose |
| carbon fixation | attaches each CO2 molecule to a 5-carbon sugar, RuBP |
| Rubisco | enzyme which catalyzes carbon fixation; most abundant protein in chloroplasts, possibly on Earth |
| reduction | each 3-phosphoglycerate gains a new phosphate group from ATP, becoming 3-biphosphoglycerate; pair of electrons from NADPH reduce it, making it G3P |
| regeneration of CO2 acceptor (RuBP) | using more ATP, carbon skeletons of 5 molecules of G3P are rearranged to 3 molecules of RuBP, in order to receive more CO2 |
| C3 plants | plants that start Calvin cycle with the carbon fixation of a 3-carbon compound, 3-phosphoglycerate |
| photorespiration | when it is too hot and dry so a plant's stomata close up but then they can't get CO2 in, so instead they start the Calvin cycle with oxygen; this spends ATP and makes no sugar |
| C4 plants | first fixes CO2 into a modified 4-carbon compound |
| crassulacean acid metabolism (CAM) | when stomata is closed during the day and opened at night (CAM plants) |
Created by:
cramdel37
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