AP® biology unit 2 Flashcards
AP® biology unit 2
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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 assist in cell membrane function? They help transport substances, act as enzymes, or serve as receptors. What is the difference between passive and active transport? Passive transport does not require energy, while active transport does. What is osmosis? The diffusion of water across a selectively permeable membrane. Define facilitated diffusion. The process of spontaneous passive transport of molecules across a biological membrane via specific transmembrane proteins. What is the role of cholesterol in the cell membrane? It helps maintain fluidity and stability of the membrane. Explain the term 'selectively permeable'. A property of cell membranes that allows some substances to pass through while others cannot. What is the function of glycoproteins in the cell membrane? They play a role in cell recognition and signaling. How does temperature affect membrane fluidity? Higher temperatures increase fluidity, while lower temperatures decrease it. What is endocytosis? The process by which cells take in substances by engulfing them in a vesicle. Describe the process of exocytosis. The release of substances from a cell when a vesicle fuses with the cell membrane. What is the role of aquaporins? They facilitate the transport of water across cell membranes. What is the significance of the sodium-potassium pump? It helps maintain the electrochemical gradient across the cell membrane. How do ion channels function? They allow specific ions to pass through the membrane in response to a signal. What is the difference between hypertonic and hypotonic solutions? Hypertonic solutions have a higher solute concentration, while hypotonic solutions have a lower solute concentration. What is the role of the cytoskeleton in cell membrane function? It provides structural support and helps maintain the shape of the cell. What is the function of carrier proteins? They transport specific substances across the cell membrane. What is the role of ATP in active transport? ATP provides the energy needed to move substances against their concentration gradient.