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Bio Chapter 5
| Question | Answer |
|---|---|
| 1. What is the main function of the plasma membrane? | A selective barrier that controls what enters and leaves the cell. |
| What is the plasma membrane made of? | A phospholipid bilayer with proteins and other molecules. |
| What are the two parts of a phospholipid | A hydrophilic (water-loving) head and hydrophobic (water-fearing) tails |
| What does the fluid mosaic model describe? | A flexible, constantly changing bilayer with proteins embedded in it. |
| What are ICF, ECF, and interstitial fluid? | ICF: fluid inside cells. ECF: fluid outside cells. Interstitial fluid: ECF surrounding cells. |
| What is a transmembrane protein? | A protein that spans the entire plasma membrane. |
| What is an integral protein? | A protein embedded in the membrane; some span the entire bilayer. |
| What is a peripheral protein? | A protein attached to the membrane’s inner or outer surface. |
| What is a glycoprotein? | A protein with attached carbohydrate (sugar) chains. |
| What is a glycolipid? | A lipid with an attached carbohydrate (sugar) chain. |
| What does cholesterol do in the membrane? | Helps maintain membrane fluidity and stability. |
| What are the six major functions of membrane proteins? | Transport, signal reception, attachment, enzymatic activity, intercellular joining, and cell recognition. |
| How do membrane proteins transport substances? | They act as channels, carriers, or pumps. |
| How do membrane receptors work? | They bind specific chemical messengers and trigger cell responses. |
| How do membrane proteins help maintain cell shape? | They anchor the cytoskeleton and extracellular matrix. |
| What is the enzymatic function of membrane proteins? | They speed up chemical reactions. |
| What is cell-cell recognition? | Cells identify one another using specific surface markers. |
| What is the glycocalyx? | A sugar coating made from carbohydrates attached to membrane lipids and proteins. |
| How does the glycocalyx help the immune system? | It helps distinguish the body’s own cells from foreign cells. |
| What are the three main types of cell junctions? | Tight junctions, desmosomes, and gap junctions. |
| What do tight junctions do? | Seal neighboring cells to prevent substances from passing between them. |
| Where are tight junctions especially important? | In linings such as the gastrointestinal tract. |
| What do desmosomes do? | Anchor neighboring cells together like rivets and resist tearing. |
| What do gap junctions do? | Form channels that let ions and small molecules pass between cells. |
| What is selective permeability? | Allowing some substances to cross the membrane while restricting others. |
| What are the two main categories of membrane transport? | Passive transport and active transport. |
| What is passive transport? | Movement down a concentration gradient without cellular ATP. |
| What is a concentration gradient? | A difference in a substance’s concentration between two areas. |
| What is diffusion? | Net movement of particles from higher to lower concentration. |
| What factors affect diffusion speed? | Temperature, molecule size, and the concentration gradient. |
| What is simple diffusion? | Movement directly through the lipid bilayer without transport proteins or ATP. |
| Which substances cross by simple diffusion? | Small nonpolar or lipid-soluble molecules, such as oxygen and carbon dioxide. |
| What is facilitated diffusion? | Passive movement through membrane proteins without ATP. |
| What is carrier-mediated facilitated diffusion? | A specific substance binds to a carrier protein, which changes shape to move it across. |
| What limits carrier-mediated diffusion? | The number of available carriers; they can become saturated. |
| What is channel-mediated facilitated diffusion? | Substances pass through selective protein channels down their gradients. |
| What are aquaporins? | Membrane channel proteins that allow water to cross. |
| What is osmosis? | Net movement of water across a selectively permeable membrane. |
| In osmosis, which way does water move? | Toward the side with the higher concentration of nonpenetrating solutes. |
| Why is osmosis important to cells? | It changes cell volume and can cause cells to swell or shrink. |
| What is tonicity? | A solution’s ability to change a cell’s water volume. |
| What happens to a cell in an isotonic solution? | It stays about the same size because there is no net water movement. |
| What happens to a cell in a hypertonic solution? | Water leaves the cell, so it shrinks. |
| What happens to a cell in a hypotonic solution? | Water enters the cell, so it swells and may burst. |
| What is filtration? | Movement of water and small solutes driven by pressure, often across capillary walls. |
| What is active transport? | Movement against a concentration gradient using energy and transport proteins. |
| What are the two main types of active transport? | Active transport by pumps and vesicular transport. |
| What is the sodium-potassium pump called? | Na⁺/K⁺-ATPase. |
| What does the sodium-potassium pump move per cycle? | 3 Na⁺ out of the cell and 2 K⁺ into the cell, using ATP. |
| Why is the sodium-potassium pump important? | It maintains high intracellular K⁺ and high extracellular Na⁺. |
| What is vesicular transport? | Movement of large particles, macromolecules, or fluids using membrane-bound vesicles. |
| What is exocytosis? | Vesicles fuse with the plasma membrane to release substances outside the cell. |
| What are examples of exocytosis? | Hormone secretion, neurotransmitter release, mucus secretion, and waste removal. |
| What is endocytosis? | The cell brings substances inside by forming vesicles from its membrane. |
| What are the three types of endocytosis? | Phagocytosis, pinocytosis, and receptor-mediated endocytosis. |
| What is phagocytosis? | The cell engulfs large particles using extensions called pseudopods. |
| What is a phagosome? | A vesicle containing material engulfed during phagocytosis. |
| Which cells commonly perform phagocytosis? | Macrophages and certain other white blood cells. |
| What is pinocytosis? | The cell takes in extracellular fluid and dissolved substances in small vesicles. |
| What is receptor-mediated endocytosis? | Selective uptake of substances that bind to specific membrane receptors. |
| What are clathrin-coated pits? | Membrane regions that help form vesicles during receptor-mediated endocytosis. |
| What is transcytosis? | Transport into a cell, across it in vesicles, and out the other side. |
| What is the difference between diffusion and active transport? | Diffusion moves down a gradient without ATP; active transport moves against a gradient using energy. |
| What is the difference between endocytosis and exocytosis? | Endocytosis brings substances in; exocytosis releases substances out. |
| Practice Cell Diagram |
Created by:
bethanygumpel