AP Bio Unit 2
1. Phospholipid
Definition: A molecule made up of a glycerol backbone, two fatty acid tails, and a phosphate group.
Function: Forms the structural foundation of cell membranes, creating a semi-permeable barrier.
2. Bilayer
Definition: Two layers of phospholipids arranged tail-to-tail.
Function: Forms the basis of the cell membrane, allowing selective permeability.
3. Cell Membrane
Definition: A semi-permeable membrane made of a phospholipid bilayer and proteins.
Function: Regulates what enters and exits the cell.
4. Ribosome
Definition: A complex of RNA and protein.
Function: Synthesizes proteins from mRNA in both prokaryotes and eukaryotes.
5. Chloroplast
Definition: Organelles found in plant cells and some protists.
Function: Conducts photosynthesis to convert light energy into chemical energy.
6. Mitochondria
Definition: Double-membraned organelles found in eukaryotic cells.
Function: Produces ATP through cellular respiration.
7. Cytoskeleton
Definition: A network of fibers made of proteins like actin, tubulin, and intermediate filaments.
Function: Provides structural support and helps with cell movement.
8. Endoplasmic Reticulum (Smooth & Rough)
Definition: A network of membranes within the cell.
Function:
- Rough ER: Synthesizes proteins (ribosome-studded).
- Smooth ER: Synthesizes lipids, detoxifies, and stores calcium ions.
9. Golgi Complex
Definition: A series of flattened membrane sacs.
Function: Modifies, sorts, and packages proteins and lipids for transport.
10. Nucleus
Definition: The membrane-bound organelle containing DNA in eukaryotic cells.
Function: Controls cell activities and contains genetic material.
11. Vacuole
Definition: A large membrane-bound organelle.
Function: Stores nutrients, waste products, and maintains turgor pressure in plant cells.
12. Lysosome
Definition: Membrane-bound organelles containing digestive enzymes.
Function: Breaks down waste materials and cellular debris.
13. Cell Wall
Definition: A rigid outer layer found in plant cells, fungi, and bacteria.
Function: Provides structural support and protection.
14. Prokaryote
Definition: A single-celled organism without a nucleus or membrane-bound organelles.
Example: Bacteria and archaea.
15. Eukaryote
Definition: Organisms whose cells contain a nucleus and membrane-bound organelles.
Example: Animals, plants, fungi, and protists.
16. Cellulose
Definition: A polysaccharide composed of glucose units.
Function: Forms the structural component of plant cell walls.
17. Cellular Respiration
Definition: A process that converts glucose into ATP with the help of oxygen.
Equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP
18. Photosynthesis
Definition: A process in plants and some protists that converts light energy into chemical energy stored in glucose.
Equation: 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂
19. Thylakoid
Definition: Membrane-bound sacs inside chloroplasts.
Function: Contain chlorophyll and are the site of the light-dependent reactions of photosynthesis.
20. Granum
Definition: Stacks of thylakoids.
Function: Increase surface area for light-dependent reactions in photosynthesis.
21. Stroma
Definition: The fluid-filled space surrounding the thylakoids in a chloroplast.
Function: Site of the light-independent reactions (Calvin Cycle) in photosynthesis.
22. Inner Membrane (Mito)
Definition: The inner layer of the mitochondrion.
Function: Contains the enzymes for the electron transport chain and ATP synthesis.
23. Outer Membrane (Mito)
Definition: The outer layer of the mitochondrion.
Function: Encloses the mitochondrion and provides structure.
24. Matrix (Mito)
Definition: The inner liquid-filled space inside the mitochondrion.
Function: Contains enzymes for the Krebs cycle.
25. Intermembrane Space (Mito & Chloro)
Definition: The region between the inner and outer membranes of mitochondria and chloroplasts.
Function: Houses protons (H⁺) during the electron transport chain.
26. Surface Area
Definition: The total area of the cell's outer surface.
Function: Affects the rate of diffusion and other cellular processes.
27. Volume
Definition: The three-dimensional space inside a cell or structure.
Function: Affects the metabolic rate of a cell and the demand for resources.
28. Solute
Definition: The substance dissolved in a solution.
Example: Salt in saltwater.
29. Solvent
Definition: The substance that dissolves the solute.
Example: Water in saltwater.
30. Solution
Definition: A homogeneous mixture of solute and solvent.
31. Diffusion
Definition: The movement of molecules from an area of high concentration to an area of low concentration.
Example: Oxygen moving into cells.
32. Osmosis
Definition: The diffusion of water across a selectively permeable membrane.
Example: Water entering a plant cell.
33. Polar
Definition: Molecules with an unequal distribution of charge.
Example: Water.
34. Nonpolar
Definition: Molecules with an equal distribution of charge.
Example: Lipids.
35. Hydrophilic
Definition: Substances that are water-loving or dissolve easily in water.
Example: Salt.
36. Hydrophobic
Definition: Substances that repel water or do not dissolve in water.
Example: Oil.
37. Aquaporin
Definition: A transport protein in the cell membrane that facilitates water movement.
Function: Helps water move quickly into or out of a cell.
38. Vesicle
Definition: A small membrane-bound sac within a cell.
Function: Transports materials within the cell.
39. Transport Protein
Definition: Membrane proteins that help move substances across the cell membrane.
Function: Can facilitate active or passive transport.
40. Active Transport
Definition: The movement of molecules against their concentration gradient, requiring energy (ATP).
Example: Sodium-potassium pump.
41. Passive Transport
Definition: The movement of molecules down their concentration gradient, without the use of energy.
Example: Diffusion.
42. Facilitated Diffusion
Definition: The passive transport of molecules via a transport protein.
Example: Glucose transport through a membrane.
43. Integral Proteins
Definition: Membrane proteins that span the entire lipid bilayer.
Function: Involved in transport and communication.
44. Peripheral Proteins
Definition: Membrane proteins that are attached to the surface of the lipid bilayer.
Function: Involved in cell signaling and maintaining the cell's shape.
45. Surface Area to Volume Ratio
Definition: The ratio of the surface area of a cell to its volume.
Function: A higher ratio improves the cell's efficiency in exchanging materials with its environment.
46. Ion
Definition: An atom or molecule with a net electrical charge due to the loss or gain of electrons.
Example: Na⁺ or Cl⁻.
47. Concentration Gradient
Definition: The difference in concentration of a substance across a space.
Function: Determines the direction of diffusion.
48. Equilibrium
Definition: The state in which the concentrations of a substance are equal throughout a system.
Function: No net movement of molecules occurs at equilibrium.
49. Water Potential
Definition: A measure of the potential energy of water in a system.
Function: Determines the direction of water movement.
50. Solute Potential
Definition: The potential of a solution to take up water due to the presence of solutes.
Function: More solutes = lower solute potential.
51. Pressure Potential
Definition: The physical pressure exerted on water in a plant cell.
Function: Can be positive (turgor pressure) or negative (tension in xylem).
52. Positive Pressure
Definition: Pressure exerted on water inside a plant cell that pushes against the cell wall.
Function: Helps maintain cell shape and rigidity.
53. Negative Pressure
Definition: Pressure exerted in the xylem during transpiration.
Function: Pulls water upward in plants.
54. Stomata
Definition: Small pores on plant leaves that regulate gas exchange.
Function: Allow CO₂ in and O₂ out, while controlling water loss.
55. Molarity
Definition: A measure of the concentration of a solution, expressed in moles of solute per liter of solution.
Example: 1 M NaCl solution.
56. Cholesterol
Definition: A lipid molecule found in the cell membrane.
Function: Helps maintain membrane fluidity and stability.
57. Exocytosis
Definition: The process by which cells expel materials using vesicles.
Example: Release of neurotransmitters.
58. Endocytosis
Definition: The process by which cells take in materials via vesicle formation.
Example: Phagocytosis in immune cells.
59. Turgid / Turgor Pressure
Definition: The pressure within a plant cell due to water intake.
Function: Helps maintain cell shape and prevents wilting.
60. Flaccid
Definition: A state of plant cells when they are not turgid.
Function: Occurs when water is lost, causing the cell to shrink.
61. Cell Compartmentalization
Definition: The process by which cells use membranes to divide the cell into distinct functional regions.
Function: Increases efficiency by isolating different biochemical processes.
62. Endosymbiosis
Definition: The theory that mitochondria and chloroplasts originated as free-living prokaryotes that were engulfed by a host cell.
Function: Explains the similarities between these organelles and prokaryotes.
63. DNA
Definition: Deoxyribonucleic acid, the molecule that carries genetic information.
Function: Directs cell activities and inheritance.
64. ATP
Definition: Adenosine triphosphate, the main energy carrier in cells.
Function: Provides energy for cellular processes.
65. Cytosol
Definition: The fluid portion of the cytoplasm, excluding organelles.
Function: Site for many cellular processes, like glycolysis.
66. Permeable / Semi-permeable
Definition:
- Permeable: Allows all substances to pass.
- Semi-permeable: Allows only certain substances to pass through.
67. Hydrolysis
Definition: The breakdown of a molecule using water.
Example: Breaking down polymers into monomers.
68. Enzymes
Definition: Proteins that catalyze biochemical reactions.
Function: Speed up reactions by lowering activation energy.
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### 69. pH
Definition: A measure of how acidic or basic a solution is. High is basic, low is acidic
Function: Influences the shape and function of enzymes and cellular activities.
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