Cellular Energetics Knowt

Enzyme

Protein that acts as a catalyst to speed up chemical reactions.

Ribozyme

RNA molecule functioning as an enzyme.

Active Site

Region on an enzyme where the substrate binds.

Substrate

Reactant in an enzymatic reaction.

Induced Fit

The active site changes shape slightly to fit the substrate.

Cofactor

Non-protein ion or molecule required for enzyme function.

Coenzyme

Organic cofactor that assists enzymes.

Vitamins

Small organic molecules used to synthesize coenzymes.

Substrate Concentration

Higher concentration increases reaction rate until saturation.

Optimal pH

Specific pH where enzyme activity is highest; changes can disrupt enzyme function.

Temperature

Higher temperatures increase activity until denaturation.

Denature

Loss of enzyme shape and function due to temperature or pH changes.

Competitive Inhibition

Inhibitor competes with the substrate for the active site.

Noncompetitive Inhibition

Inhibitor binds elsewhere, altering enzyme shape.

Autotrophs

Organisms that make their own food (e.g., plants).

Heterotrophs

Organisms that consume others for energy.

Raw Materials for Photosynthesis

Carbon dioxide (CO₂) and water (H₂O).

Chloroplasts

Organelle where photosynthesis occurs; contains thylakoids and stroma.

Thylakoid

Flattened sac in the chloroplast where light reactions occur.

Grana

Stacks of thylakoids.

Stroma

Fluid-filled area in chloroplasts where the Calvin cycle occurs.

Chlorophyll

Pigment in thylakoid membranes that absorbs light.

Light Reactions

Occur in the thylakoid membrane; require light to produce ATP, NADPH, and oxygen.

Photosystem II

Splits water to release oxygen and electrons.

Electron Transport Chain

Transfers electrons between Photosystem II and Photosystem I, creating an H⁺ gradient.

Photosystem I

Produces NADPH by reducing NADP⁺.

ATP Synthase

Uses H⁺ gradient to synthesize ATP.

Chemiosmosis

Process of ATP production tied to an H⁺ gradient.

Calvin Cycle

Light-independent reactions in the stroma that use ATP and NADPH to convert CO₂ into sugars.

Aerobic Respiration

Requires oxygen; occurs in mitochondria.

Anaerobic Respiration

Does not require oxygen; occurs in the cytoplasm.

Glycolysis

Occurs in the cytoplasm; breaks down glucose into pyruvate, producing ATP and NADH.

Prep Reaction

Converts pyruvate into acetyl CoA, releasing CO₂ and forming NADH.

Citric Acid Cycle

Occurs in the mitochondrial matrix; produces CO₂, ATP, NADH, and FADH₂.

Electron Transport Chain (ETC)

Occurs in mitochondrial cristae; uses NADH and FADH₂ to produce ATP.

ATP

Main energy currency of the cell.

NADH/FADH₂

Electron carriers in cellular respiration.

Chemiosmosis

Uses H⁺ gradient in mitochondria to produce ATP.

Glycolysis Reactants

Glucose, 2 NAD⁺, 2 ATP, 4 ADP+P.

Glycolysis Products

2 Pyruvate, 2 NADH, 4 ATP (net gain of 2).

Citric Acid Cycle Reactants

2 Acetyl CoA, 6 NAD⁺, 2 FAD, 2 ADP+P.

Citric Acid Cycle Products

4 CO₂, 6 NADH, 2 FADH₂, 2 ATP.

ETC Reactants

10 NADH, 2 FADH₂, 6 O₂.

ETC Products

34-36 ATP, 6 H₂O.

Metabolic Pathway

Ordered sequence of linked reactions.

Activation Energy

Energy needed to start a reaction.

Coupled Reactions

Energy-releasing reactions drive energy-requiring reactions.