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Anatomy & Physiology: Cells and Membrane Transport

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Terms in this set (27)

  • What are the three basic parts of a typical human cell?

    Plasma membrane: flexible outer boundary, cytoplasm: intracellular fluid with organelles, and nucleus: DNA-containing control center.

  • What is the plasma membrane composed of and its main function?

    A phospholipid bilayer with cholesterol and embedded proteins; it acts as an active barrier controlling entry and exit of substances.

  • Describe the polarity of phospholipids in the plasma membrane.

    Phosphate heads are polar and hydrophilic (water-loving), while fatty acid tails are nonpolar and hydrophobic (water-hating).

  • What are the two main types of membrane proteins and their functions?

    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.

  • Name and describe the three types of cell junctions.

    Tight junctions: impermeable seals, desmosomes: anchoring junctions preventing tearing, gap junctions: channels allowing molecule and ion passage.

  • What is the glycocalyx and its role?

    A sugar coating of glycoproteins and glycolipids on the cell surface that acts as a biological marker for cell recognition and immune response.

  • Define passive transport and list its three types.

    Movement of substances across the membrane without energy, including simple diffusion, facilitated diffusion, and osmosis.

  • What factors influence the speed of diffusion?

    Concentration gradient, molecular size, and temperature.

  • Explain simple diffusion across the plasma membrane.

    Movement of lipid-soluble molecules directly through the phospholipid bilayer, e.g., oxygen and carbon dioxide.

  • What is facilitated diffusion and its two types?

    Transport with protein assistance: carrier-mediated (specific molecules bind carriers) and channel-mediated (ions pass through protein channels).

  • Describe osmosis and how water crosses the plasma membrane.

    Movement of water through a selectively permeable membrane via lipid bilayer or aquaporin channels, from low to high solute concentration.

  • What is osmolarity and how does it affect water movement?

    Total solute concentration; water moves by osmosis from areas of low solute (high water) to high solute (low water) concentration.

  • Compare isotonic, hypertonic, and hypotonic solutions in relation to cells.

    Isotonic: no volume change, hypertonic: cell shrinks (crenation), hypotonic: cell swells and may burst (lysis).

  • What is active transport and why is energy required?

    Movement of solutes against their concentration gradient using energy (ATP) via carrier proteins or vesicles.

  • Differentiate primary and secondary active transport.

    Primary: ATP hydrolysis powers pumps directly. Secondary: uses energy stored in ion gradients created by primary transport.

  • Describe the sodium-potassium pump function.

    Pumps 3 Na+ out and 2 K+ into the cell per ATP, maintaining electrochemical gradients essential for nerve and muscle function.

  • What are antiporters and symporters in active transport?

    Antiporters move two substances in opposite directions; symporters move two substances in the same direction, both requiring ATP.

  • What is vesicular transport and its three types?

    Energy-dependent transport of large substances via vesicles: transcytosis, vesicular trafficking, and endocytosis (phagocytosis, pinocytosis, receptor-mediated).

  • Explain exocytosis and its purpose.

    Process where vesicles fuse with plasma membrane to eject substances like hormones, neurotransmitters, or wastes from the cell.

  • What is the cytoplasm composed of?

    Includes cytosol (gel-like fluid), inclusions (insoluble molecules), and organelles (specialized structures).

  • Name major membranous organelles and their functions.

    Mitochondria (ATP production), rough and smooth ER (protein and lipid synthesis), Golgi apparatus (packaging), lysosomes (digestion), peroxisomes (detoxification).

  • What are non-membranous organelles and their roles?

    Ribosomes (protein synthesis), cytoskeleton (structure and movement), centrioles (cell division and cilia/flagella formation).

  • What are cilia and flagella functions?

    Cilia move substances across cell surfaces; flagella propel the entire cell.

  • What are microvilli and their function?

    Fingerlike plasma membrane projections that increase surface area for absorption, supported by actin filaments.

  • What are the main components and functions of the nucleus?

    Contains nuclear envelope, nucleoli, and chromatin; stores genetic material and controls protein synthesis.

  • Describe the cell cycle phases relevant to cell division.

    Interphase: cell growth and normal activity; mitotic phase: mitosis (nuclear division) and cytokinesis (cytoplasm division).

  • What is the role of RNA in protein synthesis?

    RNA copies DNA code (transcription) and carries it to ribosomes for protein assembly (translation); types include mRNA, rRNA, and tRNA.