AP Bio Unit 3 Flashcards

Enzymes

Biological catalysts used to speed up biological processes.

Ribozymes

Biological catalysts made of RNA.

Active site

Part of an enzyme that interacts with the substrate.

Substrate

The reactant that binds to the active site of an enzyme.

Denaturation

Changes to an enzyme's structure that can limit its ability to catalyze chemical reactions.

Competitive inhibitors

Molecules that compete with substrates for the active site of an enzyme.

Non-competitive (allosteric) inhibitors

Molecules that bind to a different site on the enzyme, changing its shape and reducing enzyme-substrate bonding.

Cofactors

Inorganic molecules and coenzymes that increase the efficiency of enzyme-catalyzed reactions.

Activation energy (Ea)

The energy difference between the reactants and the transition state of a chemical reaction.

Endergonic reaction

A reaction with products at higher free energy levels than the reactants.

Exergonic reaction

A reaction with products at lower free energy levels than the reactants.

Coupled reactions

Pairing exergonic reactions with endergonic reactions to transfer energy between molecules.

Heterotrophs

Organisms that obtain energy by consuming other organisms.

Autotrophs

Organisms that produce their own organic molecules from inorganic molecules.

Photo-autotrophs

Autotrophs that use light energy to power the process of photosynthesis.

Light-dependent reactions

Use energy from sunlight to split water and produce oxygen, protons, and high-energy electrons.

Light-independent reactions (Calvin Cycle)

Use ATP, NADPH, and carbon dioxide to produce sugars.

Photophosphorylation

Conversion of ADP to ATP using the energy of sunlight.

Chlorophyll

Light-absorbing pigment that captures the energy of photons from the sun.

Photosystems

Composed of proteins, chlorophyll, and accessory pigments that absorb light energy.

Electron transport chain (ETC)

Series of protein carriers that transfer electrons between photosystems.

Photolysis

Splitting of water molecules using light energy, producing oxygen gas, protons, and electrons.

Chemiosmosis

Process of using a proton gradient and ATP synthase to produce ATP.

Light-independent reactions (Calvin Cycle)

Occur in the stroma of the chloroplast and involve the fixation, reduction, and regeneration of carbon.

Glycolysis

Process that occurs in the cytosol of all organisms, breaking down glucose into pyruvate and producing ATP and NADH.

Oxidation of pyruvate

Process that occurs in the mitochondria, converting pyruvate into acetyl CoA and producing NADH.

Krebs cycle (citric acid cycle)

Series of reactions in the mitochondria that produces ATP, NADH, and FADH2.

Oxidative phosphorylation

Process that occurs in the mitochondria, using the electron transport chain to generate ATP.

Fermentation

Process that occurs in the absence of oxygen, allowing for the production of ATP through glycolysis.

Coenzyme A

Molecule that attaches to the acetyl group and delivers it to the Krebs cycle.

Glycolysis

The process in which each molecule of glucose generates 2 pyruvate molecules and occurs in the cytosol.

Oxidation of Pyruvate

The process in which pyruvate is converted to acetyl group and occurs twice for each molecule of glucose.

Location

The specific site where a process occurs, such as the mitochondria or the matrix of the mitochondria.

Inputs

The substances or molecules that are used as starting materials for a process, such as pyruvate or acetyl group.

Outputs

The substances or molecules that are produced as a result of a process, such as acetyl group or carbon dioxide.

Mitochondria

The organelle where cellular respiration takes place, including the Krebs Cycle and oxidative phosphorylation.

Pyruvate

A 3-carbon molecule produced during glycolysis that can be further oxidized to acetyl group.

Acetyl Group

A 2-carbon molecule that is derived from pyruvate and enters the Krebs Cycle.

NAD+

A coenzyme that accepts electrons during cellular respiration and is reduced to NADH.

Carbon Dioxide

A 1-carbon molecule that is produced during the Krebs Cycle and released as a waste product.

NADH

A reduced form of NAD+ that carries high-energy electrons to the electron transport chain for oxidative phosphorylation.

Krebs Cycle (Citric Acid Cycle)

A series of enzyme-catalyzed reactions in the matrix of the mitochondria that generates ATP, NADH, FADH2, and carbon dioxide.

Matrix of Mitochondria

The liquid center of the mitochondria where the Krebs Cycle takes place.

FAD+

A coenzyme that accepts electrons during cellular respiration and is reduced to FADH2.

FADH2

A reduced form of FAD+ that carries high-energy electrons to the electron transport chain for oxidative phosphorylation.

ADP + Pi

Adenosine diphosphate and inorganic phosphate, which combine to form ATP through substrate-level phosphorylation.

ATP

Adenosine triphosphate, a molecule that stores and provides energy for cellular processes.

Total Products of Glycolysis, Oxidation of Pyruvate, and Krebs Cycle

The cumulative outputs of ATP, NADH, FADH2, and carbon dioxide for each molecule of glucose.

Oxidative Phosphorylation

The process that involves the electron transport chain and chemiosmosis to produce ATP in cellular respiration.

Electron Transport Chain (ETC)

A series of protein complexes in the mitochondrial membrane that transfer electrons and release energy.

Chemiosmosis

The process in which a proton gradient is used to produce ATP through the flow of protons across the mitochondrial membrane.

Proton Gradient

The difference in concentration of protons (H+) across the mitochondrial membrane, created by the electron transport chain.

ATP Synthase

An enzyme that catalyzes the production of ATP using the energy from the flow of protons through its channel.

Fermentation

The process that occurs in the absence of oxygen to regenerate NAD+ and sustain glycolysis, producing either alcohol or lactic acid.

Alcohol Fermentation

A type of fermentation where pyruvate is converted to alcohol (usually ethanol) and CO2 is produced.

Lactic Acid Fermentation

A type of fermentation where pyruvate is converted to lactic acid and no CO2 is produced.

Photosynthesis

The process that converts solar energy into chemical energy within chloroplasts.

Chloroplasts

Organelles found in plants and other photosynthetic organisms that contain chlorophyll and are responsible for photosynthesis.

Carotenoids

Pigments that produce the red, orange, and yellow colors in plants and are involved in photosynthesis.

Autotrophs

Organisms that can sustain themselves without eating anything derived from other organisms, producing organic molecules from CO2 and other inorganic molecules.

Heterotrophs

Organisms that obtain organic material from other organisms.

Decomposers

Organisms that consume dead organic material or feces.

Fossil Fuels

Earth's supply of fossil fuels, formed from the remains of organisms that died hundreds of millions of years ago.

Stomata

Microscopic pores in leaves through which CO2 enters and O2 exits.

Stroma

Dense fluid within the chloroplast envelope.

Thylakoids

Connected sacs in the chloroplast that compose a third membrane system.

Chlorophyll

The pigment that gives leaves their green color and resides in the thylakoid membranes.

Light Reactions

The first stage of photosynthesis that occurs in the thylakoids and converts solar energy to ATP and NADPH.

Calvin Cycle

The second stage of photosynthesis that occurs in the stroma and uses ATP and NADPH to reduce CO2 and form sugar.

Electromagnetic Spectrum

The entire range of electromagnetic energy or radiation.

Action Spectrum

The relative effectiveness of different wavelengths of radiation in driving a process.

Photosystems

Consist of a reaction-center complex surrounded by light-harvesting complexes.

Linear Electron Flow

The primary pathway of electron flow during the light reactions that produces ATP and NADPH.

Cyclic Electron Flow

Electron flow that cycles back from Fd to the PSI reaction center, producing ATP but not NADPH.

Chemiosmosis

The process by which ATP is generated using a proton gradient.

Calvin Cycle

The process in which ATP and NADPH are used to reduce CO2 and build sugar molecules.

Calvin Cycle

The biochemical process in which carbon dioxide is fixed and converted into glucose.

Carbon Fixation

The process by which carbon dioxide is converted into organic molecules, such as G3P, through the action of enzymes like rubisco.

Rubisco

An enzyme that catalyzes the fixation of carbon dioxide onto a molecule called RuBP during the Calvin Cycle.

G3P

A three-carbon molecule that is an important intermediate in the Calvin Cycle and serves as a precursor for glucose synthesis.

RuBP

Ribulose-1,5-bisphosphate, a five-carbon molecule that serves as the acceptor of carbon dioxide during the Calvin Cycle.

ATP

Adenosine triphosphate, a molecule that provides energy for cellular processes.

NADPH

Nicotinamide adenine dinucleotide phosphate, a molecule that carries high-energy electrons used in the Calvin Cycle.

PGA

3-phosphoglycerate, a three-carbon compound formed during carbon fixation in the Calvin Cycle.

Photorespiration

A process that occurs when rubisco adds oxygen instead of carbon dioxide during the Calvin Cycle, leading to the release of carbon dioxide without the production of ATP or sugar.

C4 Plants

Plants that have adapted a specialized pathway to minimize photorespiration by incorporating carbon dioxide into four-carbon compounds before entering the Calvin Cycle.

Bundle Sheath Cells

Cells arranged in tightly packed sheaths around the veins of the leaf in C4 plants, where the Calvin Cycle occurs.

Mesophyll Cells

Loosely packed cells between the bundle sheath and the leaf surface in C4 plants, where carbon dioxide is initially fixed into four-carbon compounds.

PEP Carboxylase

An enzyme found in mesophyll cells of C4 plants that has a higher affinity for CO2 than rubisco, allowing it to fix carbon even at low concentrations.

CAM Plants

Plants that use crassulacean acid metabolism to fix carbon dioxide at night and release it during the day for the Calvin Cycle.

Stomata

Small openings on the surface of leaves that allow for gas exchange, including the uptake of carbon dioxide and release of oxygen.

Starch

A complex carbohydrate that plants store as an energy reserve, particularly in chloroplasts, roots, tubers, seeds, and fruits.