AP® biology unit 4 Flashcards
AP® biology unit 4
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What is the primary function of the cell membrane? To regulate the movement of substances in and out of the cell. Describe the fluid mosaic model. A model that describes the cell membrane as a flexible layer made of lipid molecules interspersed with proteins. What role do phospholipids play in the cell membrane? They form a bilayer that acts as a barrier to most water-soluble substances. How do proteins function in the cell membrane? They assist in transport, act as enzymes, or serve as receptors. What is passive transport? The movement of substances across the cell membrane without the use of energy. Define osmosis. The diffusion of water across a selectively permeable membrane. What is active transport? The movement of substances against their concentration gradient, requiring energy. Explain the role of ATP in active transport. ATP provides the energy needed to move substances against their concentration gradient. What is endocytosis? The process by which cells take in substances by engulfing them in a vesicle. Describe exocytosis. The process by which cells expel materials using vesicles that fuse with the plasma membrane. What is the function of cholesterol in the cell membrane? It helps to stabilize the membrane's fluidity. How do glycoproteins function in the cell membrane? They play a role in cell recognition and signaling. What is facilitated diffusion? The process of passive transport of molecules across a membrane via specific transmembrane proteins. What is the role of aquaporins? They facilitate the rapid transport of water across the cell membrane. Define isotonic solution. A solution where the concentration of solutes is equal inside and outside the cell. What happens to a cell in a hypertonic solution? The cell will lose water and shrink. What is a hypotonic solution? A solution with a lower concentration of solutes compared to the cell's interior. What is the sodium-potassium pump? A type of active transport that moves sodium out of the cell and potassium into the cell. How does temperature affect membrane fluidity? Higher temperatures increase fluidity, while lower temperatures decrease it. What is the role of carrier proteins? They transport specific substances across the cell membrane. What is the significance of membrane potential? It is the voltage difference across a membrane, important for nerve impulse transmission. How do ion channels function? They allow specific ions to pass through the membrane, facilitating electrical signaling. What is receptor-mediated endocytosis? A selective uptake of molecules into a cell by binding to a receptor. What is the role of the cytoskeleton in membrane function? It provides structural support and helps in cell movement and transport. How do lipid rafts function in the cell membrane? They organize the assembly of signaling molecules, influencing membrane fluidity and protein trafficking.