뒤로Anatomy & Physiology: Cells and Membrane Transport
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Plasma membrane: flexible outer boundary, cytoplasm: intracellular fluid with organelles, and nucleus: DNA-containing control center.
A phospholipid bilayer with cholesterol and embedded proteins; it acts as an active barrier controlling entry and exit of substances.
Phosphate heads are polar and hydrophilic (water-loving), while fatty acid tails are nonpolar and hydrophobic (water-hating).
Integral proteins span the membrane and function as transporters, enzymes, or receptors. Peripheral proteins attach loosely and function in enzymes, motor proteins, and cell connections.
Tight junctions: impermeable seals, desmosomes: anchoring junctions preventing tearing, gap junctions: channels allowing molecule and ion passage.
A sugar coating of glycoproteins and glycolipids on the cell surface that acts as a biological marker for cell recognition and immune response.
Movement of substances across the membrane without energy, including simple diffusion, facilitated diffusion, and osmosis.
Concentration gradient, molecular size, and temperature.
Movement of lipid-soluble molecules directly through the phospholipid bilayer, e.g., oxygen and carbon dioxide.
Transport with protein assistance: carrier-mediated (specific molecules bind carriers) and channel-mediated (ions pass through protein channels).
Movement of water through a selectively permeable membrane via lipid bilayer or aquaporin channels, from low to high solute concentration.
Total solute concentration; water moves by osmosis from areas of low solute (high water) to high solute (low water) concentration.
Isotonic: no volume change, hypertonic: cell shrinks (crenation), hypotonic: cell swells and may burst (lysis).
Movement of solutes against their concentration gradient using energy (ATP) via carrier proteins or vesicles.
Primary: ATP hydrolysis powers pumps directly. Secondary: uses energy stored in ion gradients created by primary transport.
Pumps 3 Na+ out and 2 K+ into the cell per ATP, maintaining electrochemical gradients essential for nerve and muscle function.
Antiporters move two substances in opposite directions; symporters move two substances in the same direction, both requiring ATP.
Energy-dependent transport of large substances via vesicles: transcytosis, vesicular trafficking, and endocytosis (phagocytosis, pinocytosis, receptor-mediated).
Process where vesicles fuse with plasma membrane to eject substances like hormones, neurotransmitters, or wastes from the cell.
Includes cytosol (gel-like fluid), inclusions (insoluble molecules), and organelles (specialized structures).
Mitochondria (ATP production), rough and smooth ER (protein and lipid synthesis), Golgi apparatus (packaging), lysosomes (digestion), peroxisomes (detoxification).
Ribosomes (protein synthesis), cytoskeleton (structure and movement), centrioles (cell division and cilia/flagella formation).
Cilia move substances across cell surfaces; flagella propel the entire cell.
Fingerlike plasma membrane projections that increase surface area for absorption, supported by actin filaments.
Contains nuclear envelope, nucleoli, and chromatin; stores genetic material and controls protein synthesis.
Interphase: cell growth and normal activity; mitotic phase: mitosis (nuclear division) and cytokinesis (cytoplasm division).
RNA copies DNA code (transcription) and carries it to ribosomes for protein assembly (translation); types include mRNA, rRNA, and tRNA.