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fermentation

catabolic process that is a partial degradation of sugars that occurs without the use of oxygen

cellular respiration

catabolic pathway in which oxygen is consumed as a reactant along with the organic fuel; most prevalent and efficient catabolic pathway

redox reaction

chemical reaction in which one or more electrons is transferred from one reactant to another; also called oxidation-reduction reaction

reduction

the addition of electrons to one substance in a redox reaction

oxidation

the loss of electrons from one substance in a redox reaction

reducing agent

the electron donor

oxidizing agent

the electron acceptor

NAD+

coenzyme hydrogen atoms are passed to before transferring to oxygen

electron transport chain

breaks the fall of electrons to oxygen into several energy-releasing steps instead of one explosive reaction

glycolysis

first stage of cellular respiration; occurs in the cytosol; begins degradation process by breaking glucose into two molecules of a compound called pyruvate

citric acid cycle

second stage of cellular respiration; occurs in the mitochondrial matrix; completes the breakdown of glucose by oxidizing a derivative of pyruvate to carbon dioxide

oxidative phosphorylation

mode of ATP synthesis; powered by the redox reactions of the electron transport chain

substrate-level phosphorylation

mode of ATP synthesis; smaller amount of ATP formed directly in a few reactions of glycolysis and the citric acid cycle

acetyl CoA

compound coenzyme pyruvate is first converted to after entering the mitochondrion via active transport

cytochromes

proteins that are most of the remaining electron carriers between ubiquinone and oxygen after flavoprotein returns to its oxidized form as it passes electrons to an iron-sulfur protein in the electron transport chain

ATP synthetase

the enzyme that makes ATP from ADP and inorganic phosphate; copies populate the inner membrane membrane of mitochondrion

chemiosmosis

the process in which 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

emphasizes the capacity of the H+ gradient that results from chemiosmosis to perform work

aerobic

oxygen present

anaerobic

oxygen not present

alcohol fermentation

pyruvate converted to ethanol; first, carbon dioxide released from pyruvate, which is converted to compound called acetaldehyde; next, acetaldehyde reduced to ethanol by NADH

lactic acid fermentation

pyruvate directly reduced by NADH to lactate; no release of carbon dioxide

facultative anaerobes

organisms that can make enough ATP to survive using either fermentation or respiration; examples include yeast and bacteria

beta oxidation

metabolic sequence that breaks fatty acids down to two-carbon fragments, which enter the citric acid cycle as acetyl CoA

photosynthesis

the process in which light energy from the sun is converted into chemical energy and stored in sugar and other organic molecules

autotrophs

organisms that sustain themselves without eating anything derived from other organisms

heterotrophs

organisms that obtain their organic material from the products of other organisms

chlorophyll

the green pigment located within chloroplasts

mesophyll

the tissue in the interior of the leaf; where chloroplasts are mainly found

stomata

microscopic pores through which carbon dioxide enters and oxygen exits the leaf

stroma

the dense fluid within the chloroplast

thylakoids

an elaborate system of interconnected membranous sacs; segregates the stroma from the thylakoid space

light reactions

first stage of photosynthesis; solar energy converted to chemical energy

Calvin cycle

second stage of photosynthesis; makes sugar

NADP+

an acceptor which temporarily stores energized electrons and hydrogen after being transferred from water

photophosphorylation

process by which light energy generates ATP; uses chemiosmosis to power the addition of a phosphate group to ADP

carbon fixation

the initial incorporation of carbon into organic compounds

wavelength

the distance between the crests of electromagnetic waves

electromagnetic spectrum

the entire range of radiation

visible light

radiation detected as various colors by the human eye; 380 nm to 750 nm in wavelength

photons

discrete particles of light energy

spectrophotometer

an instrument that measures the ability of a pigment to absorb various wavelengths of light

absorption spectrum

a graph plotting a pigment's light absorption versus wavelength

chlorophyll a

suggests violet-blue and red light work best for photosynthesis and green works the least

action spectrum

profiles the relative effectiveness of different wavelengths of radiation in driving photosynthesis

chlorophyll b

almost identical to chlorophyll a; slight structural difference gives two different absorption spectra

carotenoids

hydrocarbons that are various shades of yellow and orange because they absorb violet and blue-green light

photosystem

composed of a reaction center surrounded by light-harvesting complexes

light-harvesting complex

complex consisting of pigment molecules bound to particular proteins

reaction center

a protein complex that includes two special chlorophyll a molecules and a molecule called the primary electron acceptor

primary electron acceptor

molecule in reaction center that is not chlorophyll a

photosystem II

first photosystem to function; second photosystem discovered; reaction-center chlorophyll a known as P680 because this pigment is best at absorbing light having a wavelength of 680 nm (red)

photosystem I

second photosystem to function; first photosystem discovered; reaction-center chlorophyll a known as P700 because it most effectively absorbs light of wavelength 700 nm (far red)

noncyclic electron flow

predominant electron flow route; light reactions use solar power to generate ATP and NADH, which provide chemical energy and reducing power to the sugar-making reactions of the Calvin cycle

cyclic electron flow

less common electron flow route; uses photosystem I only; does not produce NADH

glyceraldehyde-3-phosphate

the carbohydrate that is a direct product of the Calvin cycle

rubisco

the enzyme that catalyzes carbon fixation

C3 plants

plants in which the first organic product of carbon fixation is a three-carbon compund; any plant in which initial fixation of carbon occurs via rubisco

photorespiration

process that occurs in the light, consumes oxygen, produces carbon dioxide, consumes ATP, and does not produce sugar

C4 plants

plants which preface the Calvi cycle with an alternate mode of carbon fixation that forms a four-carbon compound as its first product

bundle-sheath cells

cells arranged into tightly packed sheaths around the veins of the leaf

mesophyll cells

cells located between the bundle sheath and the leaf surface; loosely arranged

PEP carbohydrate

enzyme that catalyzes the addition of CO2 to phosphoenolpyruvate (PEP), forming the four-carbon product oxaloacetate

crassulacean acid metabolism (CAM)

mode of carbon fixation in which a plant opens its stomata during the night and closes them during the day

CAM plants

plants that practice CAM