AP Biology Unit 2

Plasma Membrane → A selectively permeable phospholipid bilayer that controls what enters and exits the cell.
Ribosome → Organelle responsible for protein synthesis; found in both prokaryotes and eukaryotes.
Nucleus → Membrane-bound organelle that contains DNA and controls cellular activities in eukaryotic cells.
Endoplasmic Reticulum (Rough) → Network of membranes studded with ribosomes; involved in protein synthesis and transport.
Endoplasmic Reticulum (Smooth) → Lacks ribosomes; synthesizes lipids and detoxifies toxins.
Golgi Apparatus → Modifies, sorts, and packages proteins and lipids for storage or transport out of the cell.
Mitochondrion → Powerhouse of the cell; site of cellular respiration and ATP production.
Chloroplast → Organelle found in plant cells that carries out photosynthesis using solar energy.
Lysosome → Contains digestive enzymes to break down waste, damaged organelles, and macromolecules.
Peroxisome → Breaks down fatty acids and detoxifies harmful substances.
Vacuole → Membrane-bound sac used for storage of materials; large central vacuole in plant cells helps maintain turgor pressure.
Cytoskeleton → A network of protein fibers that supports cell shape, aids in movement, and anchors organelles.
Cell Wall → Rigid outer layer in plant, fungal, and bacterial cells that provides structural support and protection.
Prokaryote → A cell lacking a nucleus and membrane-bound organelles; includes bacteria and archaea.
Eukaryote → A cell with a nucleus and membrane-bound organelles; includes plant, animal, fungal, and protist cells.
Selective Permeability → The property of membranes that allows some substances to cross more easily than others.
Phospholipid Bilayer → The fundamental structure of the plasma membrane composed of two layers of phospholipids.
Membrane Proteins → Proteins embedded in the cell membrane that assist in transport, signaling, and structural support.
Aquaporin → A channel protein that facilitates the passage of water through the membrane.
Diffusion → Passive movement of molecules from high to low concentration.
Osmosis → Diffusion of water across a selectively permeable membrane.
Facilitated Diffusion → Passive transport of substances across a membrane via transport proteins.
Active Transport → Movement of substances against their concentration gradient using energy (ATP).
Endocytosis → Process by which a cell engulfs materials from the external environment into vesicles.
Exocytosis → Process by which vesicles release their contents outside the cell.
Surface Area-to-Volume Ratio → A factor that limits cell size; a higher ratio allows more efficient exchange of materials.
Turgor Pressure → The pressure exerted by water inside the central vacuole against the cell wall of plant cells.
Plasmodesmata → Channels between plant cells that allow transport and communication.
Gap Junctions → Connections between animal cells that allow for direct communication.
Endomembrane System → A group of organelles (ER, Golgi, vesicles, etc.) that work together to modify, package, and transport proteins and lipids.