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Cell Membrane Structure and Transport Mechanisms

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Termini in questo insieme (20)

  • Effect of saturated fatty acid tails on membrane permeability

    Saturated fatty acid tails are straight and pack tightly, making the membrane less permeable and more rigid.

  • Effect of unsaturated fatty acid tails on membrane permeability

    Unsaturated fatty acid tails have kinks due to double bonds, preventing tight packing and increasing membrane permeability and fluidity.

  • Functions of the cytoskeleton

    The cytoskeleton provides structural support, facilitates cell movement, anchors organelles, and assists in intracellular transport.

  • Types of membrane specializations

    Common membrane specializations include cilia for movement, microvilli for absorption, and folds to increase surface area.

  • Function of cilia on the cell membrane

    Cilia are hair-like projections that move fluid, mucus, or cells across the membrane surface.

  • Three types of cell junctions

    The three types are tight junctions (seal cells), desmosomes (anchor cells), and gap junctions (allow communication).

  • Definition of passive transport

    Passive transport moves substances across membranes without energy, down their concentration gradient.

  • Definition of active transport

    Active transport requires energy (ATP) to move substances against their concentration gradient.

  • General principle of diffusion

    Diffusion is the movement of molecules from an area of higher concentration to lower concentration until equilibrium is reached.

  • Simple diffusion

    Movement of small or lipid-soluble molecules directly through the phospholipid bilayer without assistance.

  • Facilitated diffusion

    Passive transport of molecules via protein channels or carriers without energy use.

  • Osmosis

    Diffusion of water molecules across a selectively permeable membrane from low to high solute concentration.

  • Primary active transport

    Direct use of ATP to pump molecules against their gradient via transport proteins.

  • Secondary active transport

    Uses energy from the electrochemical gradient created by primary active transport to move other substances.

  • Endocytosis

    Process where the cell membrane engulfs material to bring it into the cell inside vesicles.

  • Exocytosis

    Process where vesicles fuse with the membrane to release contents outside the cell.

  • Role of tight junctions

    Tight junctions create a seal preventing passage of molecules between cells.

  • Role of desmosomes

    Desmosomes provide mechanical strength by anchoring cells together.

  • Role of gap junctions

    Gap junctions allow direct communication and ion exchange between adjacent cells.

  • Difference between passive and active transport

    Passive transport requires no energy and moves substances down gradients; active transport requires energy to move substances against gradients.