Unit 4: Ch's 8-10 Flashcards
Anabolic pathway
A metabolic pathway that synthesizes a complex molecule from simpler compounds
ATP
An adenine-containing nucleoside triphosphate that releases free energy when it’s phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells
ADP
A nucleotide composed of adenosine and two phosphate groups; ;formed in living cells and is an intermediate between ATP and AMP; can be turned back into ATP
Activation energy
The amount of energy that reactants must absorb before a chemical reaction will start
Active site
The specific portion of an enzyme that attaches to the substrate by means of weak chemical bonds
Acetyl CoA
Acetyl Coenzyme A; the entry compound for the citric acid cycle and cellular respiration, formed from a fragment of pyruvate attached to a coenzyme
ATP Synthase
A cluster of several membrane proteins found in the mitochondrial crista (and bacterial plasma membrane) that function in chemiosmosis with adjacent electron transport chains, using the energy of a hydrogen ion concentration gradient to make ATP. ATP synthase provide a port through which hydrogen ions diffuse into the matrix of a mitochondrion
Allosteric regulation
The binding of a molecule to a protein that affects the function of the protein at a different site
Aerobic
Containing oxygen; referring to an organism, environment, or cellular process that requires oxygen
Anaerobic
Lacking oxygen; referring to an organism, environment, or cellular process that lacks oxygen and may be poisoned by it
Alcohol fermentation
The conversion of pyruvate to carbon dioxide and ethyl alcohol
Absorption spectrum
The range of a pigment’s ability to absorb the various wavelengths of light
Beta oxidation
A metabolic sequence that breaks fatty acids down to two-carbon fragments that enter the citric acid cycle as acetyl CoA
Catabolic pathway
A metabolic pathway that releases energy by breaking down complex molecules to simpler compounds
Chemical energy
Energy stored in the chemical bonds of molecules; a form of potential energy
Catalyst
A chemical agent that changes the rate of a reaction without being consumed by the reaction
Cofactors
Any non-protein molecule or ion that is required for the proper functioning of an enzyme. Cofactors can be permanently bound to the active site or made by loosely with the substrate during catalysis
Coenzyme
An organic molecule serving as a cofactor. Most vitamins function as coenzymes and important metabolic reactions
Competitive inhibitors
A substance that reduces the activity of an enzyme by entering the active site in place of the substrate who structure it mimics
Cellular respiration
The most prevailant in efficient catabolic pathway for the production of ATP, in which oxygen is consumed as a reactant along with organic fuel
Citric acid cycle
A chemical cycle involving eight steps that completes the metabolic breakdown of glucose molecules to carbon dioxide; occurs within the mitochondrion; the second major stage in cellular respiration
Cytochromes
And iron containing protein, a component of electron transport chains in mitochondria and chloroplasts
Chemiosmosis
An energy coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP. Most ATP synthesis in cells occurs by chemiosmosis
Chlorophyll
A green pigment located with in the chloroplasts of plants. Chlorophyll a can participate directly in the light reactions, which convert solar energy to chemical energy
Calvin cycle
The second of two major stages in photosynthesis (following the light reactions), involving atmospheric CO2 fixation and reduction of the fixed carbon into carbohydrate
Carbon fixation
The incorporation of carbon from CO2 into an organic compound by an autotrophic organism (a plant, another photosynthetic organism, or a chemoautotrophic prokaryote).
Chlorophyll a
A type of blue green photosynthetic pigment that participates directly in the light reactions
Chlorophyll b
A type of yellow green accessory photosynthetic pigment that transfers energy to chlorophyll a
Carotenoids
An accessory pigment, either yellow or orange, in the chloroplasts of plants. By absorbing wavelengths of light that chlorophyll cannot, carotenoids broaden the spectrum of colors that can drive photosynthesis
Cyclic electron flow
A route of electron flow during the light reactions of photosynthesis that involves only photosystem I and that produces ATP but not NADPH or oxygen
C3 plants
A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three carbon compound as the first stable intermediate
C4 plants
A plant that prefaces the Calvin cycle with reactions that incorporate CO2 into a four carbon compound, the end product of which supplies CO2 for the Calvin cycle
CAM plants
A plants that uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions, first discovered in the family Crassulacae. Carbon dioxide entering open stomata during the night is converted into organic acids, which release CO2 for the Calvin cycle during the day, when stomata are closed
Entropy
A quantitative measure of disorder or randomness, symbolized by S
Endergonic reaction
A nonspontaneous chemical reaction, and which free energy is absorbed from the surroundings
Exergonic reaction
A spontaneous chemical reaction, in which there is a net release of energy
Enzyme
A protein serving as a catalyst, a chemical agent that changes the rate of a reaction without being consumed by the 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
Electromagnetic spectrum
The entire spectrum of radiation ranging in wavelength from less than a nanometer to more than a kilometer
First law of thermodynamics
The principle of conservation of energy. Energy can be transferred and transformed, but it cannot be created or destroyed
Fermentation
A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid
Glycolysis
The splitting of glucose into pyruvate. Glycolysis is the one metabolic pathway that occurs in all living cells, serving as the starting point for fermentation or aerobic respiration
G3P
Glyceraldehyde-3-phosphate
The carbohydrate produced directly from the Calvin cycle
Induced fit
The change in the shape of the active site of an enzyme so that it binds more snugly to the substrate, induced by entry of the substrate
Kinetic energy
The energy of motion, which is directly related to the speed of that motion. Moving matter does work by imparting motion to other matter
Lactic acid fermentation
The conversion of pyruvate to lactate with no release of carbon dioxide
Light reactions
The steps of photosynthesis that occur on the thylakoid membranes of the chloroplast and that convert solar energy to the chemical energy of ATP and NADPH, evolving oxygen in the process
Light-harvesting complex
Complex of proteins associated with pigment molecules (including chlorophyll a, chlorophyll b, and carotenoids) that captures light energy and transfers it to reaction-center pigments in a photosystem
Metabolism
The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways
Metabolic pathway
A series of chemical reactions that either build a complex molecule (anabolic pathway) or breaks down a complex molecule into simpler compounds (catabolic pathway).
Mesophyll
The ground tissue of a leaf, sandwiched between the upper and lower epidermis and specialized for photosynthesis
Noncompetitive inhibitors
A substance that reduces the activity of an enzyme by binding to a local remote from the active site, changing its conformation so that it no longer binds to the substrate
NAD+
Nicotinamide adenine dinucleotide, A coenzyme present in all cells that helps enzymes transfer electrons during the redox reactions of metabolism
NADP+
Nicotinamide adenine dinucleotide phosphate, an acceptor that temporarily stores energized electrons produced during the light reactions
Noncyclic electron flow
A route of electron flow during the light reactions of photosynthesis that involves both photosystems and produces ATP, and NADPH, and oxygen. The nets electron flow is from water to NADP+
Oxidation
The loss of electrons from a substance involved in a redox reaction.
Oxidative phosphorylation
The production of ATP using energy derived from the redox reactions of an electron transport chain
Potential energy
The energy stored by matter as a result of its location or spatial arrangement
Phosphorylated
Referring to a molecule that has been the recipient of a phosphate group
Proton-motive force
The potential energy stored in the form of an electrochemical gradient, generated by the pumping of hydrogen ions across the biological membranes during chemiosmosis
Photophosphorylation
The process of generating ATP from ADP and phosphate by means of a proton motive force generated by the thylakoid membrane of the chloroplast during the light reactions of photosynthesis
Photons
A quantum, or discrete amount, of light energy
Photosystem
Light capturing unit located in the thylakoid membrane of the chloroplast, consisting of a reaction center surrounded by numerous light harvesting complexes. There are two types of photosystems, one and two; they absorb light best at different wavelengths
Primary electron acceptor
A specialized molecule sharing the reaction center with the pair of reaction center chlorophyll a molecules; it accepts an electron from one of these two chlorophylls
Photorespiration
A metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output; generally occurs on hot, dry, bright days, when stomata close and the oxygen concentration in the leaf exceeds that of carbon dioxide
Reduction
The addition of electrons to a substance involved in a redox reaction
Reaction center
Complex of proteins associated with two special chlorophyll a molecules and a primary electron acceptor. Located centrally in a photosystem, this complex triggers the light reactions of photosynthesis. Excited by light energy, one of the chlorophylls donates an electron to the primary electronic acceptor, which passes an electron to an electron transport chain
Rubisco
Ribulose carboxylase, the enzyme that catalyzes the first step of the Calvin cycle (the addition of CO2 to RuBP, or ribulose biphosphate)
Second law of thermodynamics
The principal whereby every energy transfer or transformation increases the entropy of the universe. Ordered forms of energy are at least partly converted to heat, and in spontaneous reactions, the free energy of the system also decreases
Substrate
The reactant on which an enzyme works
Substrate-level phosphorylation
The formation of ATP by directly transferring a phosphate group to ADP it from an intermediate substrate in catabolism
Stomata
A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant
Stroma
The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water
Thermal energy
The total amount of kinetic energy due to molecular motion in a body of matter. Heat is energy in its most random form
Thermodynamics
1) The study of energy transformations that occur in a collection of matter
2) A phenomenon in which external DNA is taken up by a cell and functions there
Thylakoids
A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy
Visible light
That portion of the electromagnetic spectrum detected as a various colors by the human eye, ranging in wavelength from about 380 nm to about 750 nm
Wavelength
The distance between crests of waves, such as those of the electromagnetic spectrum
