| Term | Definition |
|---|---|
Plasma membrane
| Selective boundary controlling movement into and out of a cell
|
Phospholipid | Molecule with a water-loving head and water-fearing tails
|
Membrane protein
| Protein involved in transport, signaling, or attachment
|
Fluid mosaic model
| Flexible phospholipid bilayer with embedded molecules
|
Selectively permeable | Allows some substances through more readily than others
|
Diffusion | Net movement from higher to lower concentration
|
Osmosis | Net movement of water across a selectively permeable membrane
|
Hypertonic | Solution that causes an animal cell to lose water
|
Hypotonic | Solution that causes an animal cell to gain water
|
Isotonic | Solution with no net water movement
|
Concentration gradient
| Difference in concentration across space or a membrane
|
Active transport
| Energy-requiring transport, often against a gradient
|
ATP | Energy-transfer molecule
|
ADP | Molecule formed when ATP loses a phosphate group
|
Phosphorylation
| Addition of a phosphate group
|
Potential energy
| Stored energy
|
Endergonic | Requires a net energy input |
Exergonic | Releases energy overall |
Enzyme | Catalyst that speeds a reaction by lowering activation energy |
Activation energy | Energy barrier a reaction must overcome |
Pigment | Molecule that absorbs selected wavelengths of light |
Chlorophyll | Photosynthetic pigment that absorbs light |
Photosystem | Pigment-protein complex that captures light energy |
Electron transport chain | Series of electron carriers that transfer electrons |
H⁺ gradient | Difference in proton concentration and charge across a membrane |
ATP synthase | Enzyme that uses an H⁺ gradient to produce ATP |
NADPH | Electron carrier used in biosynthesis and the Calvin cycle |
NADH | Electron carrier used in cellular respiration |
FADH₂ | Electron carrier used in cellular respiration |
Chloroplast | Organelle where photosynthesis occurs |
Thylakoid | Membrane compartment where light reactions occur |
Stroma | Fluid-filled space surrounding thylakoids |
Calvin cycle | Reactions that incorporate CO₂ into organic molecules |
Carbon fixation | Incorporating inorganic CO₂ into organic compounds |
Rubisco | Enzyme that catalyzes CO₂ fixation and can also react with O₂ |
Photorespiration | Process initiated when rubisco reacts with O₂ |
Stomata | Leaf openings that regulate gas exchange and water loss |
Cellular respiration | Process of extracting energy from organic molecules |
Glycolysis | Breakdown of glucose into pyruvate in the cytoplasm |
Pyruvate | Three-carbon product of glycolysis |
Mitochondrion | Organelle where most aerobic respiration occurs in eukaryotes |
Krebs cycle | Cycle that produces CO₂ and electron carriers |
Fermentation | Process that regenerates NAD⁺ so glycolysis can continue |
Lactate | Product of lactic acid fermentation in humans |
Oxygen debt | Oxygen and recovery demands following strenuous activity |