AP Bio Vocabulary Unit 2 (Chapters 8-10)

Chapters 8-10

activation energy

free energy of activation - initial investment of energy for starting a reaction (the energy required to contort the reactant molecules so the bonds can break

active site

restricted region of enzyme molecule where substrate binds (a pocket or groove on the surface of the enzyme where catalysis occurs)

allosteric regulation

a protein’s function at one site is affected by the binding of a regulatory molecule to a separate site

anabolic pathways

biosynthetic pathways - consume energy to build complicated molecules from simpler ones

catabolic pathway

breakdown pathways - degradative processes that release energy by breaking down complex molecules to simpler compounds

coenzyme

organic cofactors

cofactor

non protein helpers for catalytic activity that may be bound tightly to the enzyme as a permanent resident or may bind loosely and reversibly along with the substrate

competitive inhibitor

reduce productivity of enzymes by blocking substrates from entering active sites by resembling the normal substrate molecule and competing for admissions into the active site

cooperativity

“allosteric reaction” where a substrate molecule binding to one active site in a multisubunit enzyme triggers a shape change in all the subunits, thereby increasing catalytic activity at other active sites - amplifies the response of enzymes to substrates: one substrate molecule primes an enzyme to act on additional substrate molecules more readily

endergonic reaction

absorbs free energy from surroundings - stores free energy, G is positive, and nonspontaneous

entropy

measure of disorder, or randomness: the more randomly arranged a collection of matter is, the greater the ________

enzyme

a macromolecule that acts as a catalyst

a chemical agent that speeds up a reaction without being consumed by the reaction)

exergonic reaction

net release of free energy - loss of free energy and spontaneous

feedback inhibition

a metabolic pathway is halted by the inhibitory binding of its end product to an enzyme that acts early in the pathway - metabolic control

free energy

portion of a system’s energy that can perform work when temperature and pressure are uniform throughout a system (represented by delta G - negative when it is a spontaneous process)

*G = *H - T*S

*represents delta

induced fit

when chemical groups on the active site move into positions that enhance their ability to catalyze the chemical reaction

metabolism

the chemical processes that occur within a living organism in order to maintain life

noncompetitive inhibitor

impede enzymatic reactions by binding to another part of the enzyme by causing the molecule to change its shape that the active site becomes less effective at catalyzing the conversion of substrate to product

substrate

reactant an enzyme acts on

thermodynamics

the study of energy transformations that occur in a collection of matter (has two laws that govern energy transformation)

the first law of __________ : Energy can be transferred and transformed, but it cannot be created or destroyed.

the second law of ___________: Every energy transfer or transformation increases the entropy of the universe.

acetyl CoA

(Acetyl coenzyme A) entry compound for citric acid cycle in cellular respiration, two-carbon fragment of pyruvate attached to a coenzyme

alcoholic fermentation

step one: glycolysis

step two: reduction of pyruvate to ethyl alcohol (ethanol), regenerating NAD+ and releasing CO2

ATP synthase

in the inner mitochondrial membrane of eukaryotic cells, it is a complex of membrane proteins that functions in chemiosmosis with the electron transport chains, using the H+ gradient to generate ATP

has a rod, knob, rotor, stator

cellular respiration

catabolic pathways of aerobic and anaerobic respiration, which breaks down organic molecules and uses an electron transport chain for the production of ATP

chemiosmosis

an energy-coupling mechanism that uses energy stored in the H+ gradient across a membrane to drive cellular work, such as the synthesis of ATP

citric acid cycle

a chemical cycle involving eight steps that completes the metabolic breakdown of glucose molecules begun in glycolysis by oxidizing acetyl CoA to carbon dioxide within the mitochondrion of eukaryotic cells (with pyruvate oxidation, the second major stage in cellular respiration)

cytochrome

an iron-containing protein that is a component of electron transport chains in the mitochondria and chloroplasts of eukaryotic cells

electron transport chain

a sequence of electron carrier molecules that shuttle electrons down a series of redox reactions hat release energy used to make ATP

facultative anaerobe

an organism that makes ATP by aerobic respiration, anaerobic respiration, or fermentation based on the presence of oxygen

glycolysis

a series of reactions that ultimately splits glucose into pyruvate (occurs in almost all living cells, serving as a starting point for fermentation or cellular respiration)

lactic acid fermentation

step one: glycolysis

step two: reduction of pyruvate to lactate, regenerating NAD+ with no release of CO2

obligate anaerobe

an organism that carries out only fermentation or anaerobic respiration (cannot use oxygen)

oxidative phosphorylation

the production of ATP using energy derived from the redox reactions of an electron transport chain (third major stage of cellular respiration)

proton-motive force

the potential energy stored in the form of a proton electrochemical gradient, generated by the pumping of hydrogen ions across a biological membrane during chemiosmosis

redox reaction

a chemical reaction involving the complete or partial transfer of one or more electrons from one reactant to another (reduction-oxidation reaction)

substrate-level phosphorylation

the enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism

absorption spectrum

the range of a pigment’s ability to absorb various wavelengths of light; also a graph of such a range

autotroph

an organism that obtains organic food molecules without eating other organisms or substances derived from other organisms; use energy form the sun or from oxidation of inorganic substances to make organic molecules form inorganic ones

C3 plant

a plant that uses the Calvin cycle for the initial steps that incorporate carbon dioxide into organic material, forming a three-carbon compound as the first stable intermediate

C4 plant

a plant in which the Calvin cycle is preceded by reactions that incorporate carbon dioxide into a four-carbon compound, the end product of which supplies carbon dioxide for the Calvin cycle

Calvin cycle

the second major stage in photosynthesis, involving fixation of atmospheric carbon dioxide and reduction of the fixed carbon into carbohydrate

CAM plant

a plant that uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions; in the process, carbon dioxide entering open stomata during the night is converted to organic acids, which release carbon dioxide for the Calvin cycle during the day when stomata are closed

CAM: an adaptation for photosynthesis in arid conditions, first discovered in the family Crassulaceae; in this process, a plant takes up carbon dioxide and incorporates it into a variety of organic acids at night; during the day, carbon dioxide is released form organic acids for use in the Calvin cycle

carbon fixation

the initial incorporation of carbon from carbon dioxide into an organic compound by an autotrophic organism (a plant, another photosynthetic organism, or a chemoautotrophic prokaryote)

chlorophyll

a green pigment located within the membranes of 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 (chlorophyll b is an accessory photosynthetic pigment that transfers energy to chlorophyll a) (chlorophyll b is a photosynthetic pigment that participates directly in the light reactions, which convert solar energy to chemical energy)

cyclic electron flow

a route of electron flow during the light reactions of photosynthesis that involves only one photosystem and that produces ATP and not NADPH or oxygen

electromagnetic spectrum

the entire spectrum of electromagnetic radiation, ranging in wavelength from less than a nanometer to more than a kilometer

G3P

(glyceraldehyde 3-phosphate): a three-carbon carbohydrate that is the direct product of the Calvin cycle; it is also an intermediate in glycolysis

heterotroph

an organism that obtains organic food molecules by eating other organisms or substances derived from them

light reactions

the first of two major stages of photosynthesis; occurring on the thylakoid membranes of the chloroplast or on membranes of certain prokaryotes, it converts solar energy to the chemical energy of ATP and NADPH, releasing oxygen in the process

linear electron flow

a route of electron flow during the light reactions of photosynthesis that involves both photosystems (I and II) and produces ATP, NADPH, and oxygen; the net electron flow is from water to NADP+

PEP carboxylase

an enzyme that adds carbon dioxide to phosphoenolpyruvate (PEP) to form oxaloacetate in mesophyll cells of C4 plants, acting prior to photosynthesis

photophosphorylation

the process of generating ATP from ADP and phosphate by means of chemiosmosis, using a proton-motive force generated across the thylakoid membrane of chloroplast or the membrane of certain prokaryotes during the light reactions of photosynthesis

photorespiration

a metabolic pathway that consumes oxygen and ATP, releases carbon dioxide, and decreases photosynthetic output (generally occurs on hot, dry, bright days when the stomata close and the oxygen to carbon dioxide ratio in the leaf increases, favoring the binding of oxygen rather than carbon dioxide by rubisco)

photosynthesis

the conversion of light energy to chemical energy that is stored in sugars or other organic compounds; occurs in plants, algae, and certain prokaryotes

photosystems

light-capturing units in a chloroplast’s thylakoid membrane or in the membrane of some prokaryotes, having two (different for II and I) molecules of P(680/700) chlorophyll a at its reaction center

primary electron acceptor

in the thylakoid membrane of a chloroplast or in the membrane of some prokaryotes, a specialized molecule that shares the reaction-center complex with a pair of chlorophyll a molecules and that accepts electrons from them

rubisco

(ribulose bisphosphate (RuBP) carboxylase-oxygenase) the enzyme that normally catalyzes the first step of the Calvin cycle (the addition of carbon dioxide to RuBP), binding to oxygen when excess oxygen is present or carbon dioxide levels are low, resulting in photorespiration

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