What is the primary structural component of the cell membrane?
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| 1 | What is the primary structural component of the cell membrane? |
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Details on the structure of the cell membrane, membrane proteins, and processes like diffusion, osmosis, active transport, and endocytosis.
The primary structural component of the cell membrane is a phospholipid bilayer, which consists of two layers of phospholipids with hydrophobic tails facing inward and hydrophilic heads facing outward. |
| Think of the membrane as a 'phospholipid sandwich'. |
| 2 | Name two types of membrane proteins and their functions. | Integral proteins (span the membrane, involved in transport and signaling) and peripheral proteins (attached to the membrane surface, involved in support and signaling). | Think 'inside the membrane' vs. 'on the surface'. |
| 3 | What is simple diffusion? | Simple diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration, without energy input. | Think 'down the concentration gradient'. |
| 4 | How does facilitated diffusion differ from simple diffusion? | Facilitated diffusion requires transport proteins to help move molecules across the membrane, typically for substances that cannot diffuse easily due to size or polarity. | Think 'assisted diffusion'. |
| 5 | What is osmosis? | Osmosis is the passive movement of water molecules across a selectively permeable membrane from an area of lower solute concentration to higher solute concentration. | Water moves to where the 'solute' is more concentrated. |
| 6 | Define active transport in cellular processes. | Active transport is the movement of molecules against their concentration gradient, requiring energy usually in the form of ATP, often mediated by specific transport proteins. | Think 'uphill' movement requiring energy. |
| 7 | What is the function of the sodium-potassium pump? | The sodium-potassium pump actively transports 3 sodium ions out and 2 potassium ions into the cell, helping maintain cell potential and volume. | Vital for nerve function and cellular homeostasis. |
| 8 | Explain endocytosis. | Endocytosis is a process where the cell engulfs external substances by wrapping the membrane around them, forming a vesicle to bring materials inside. | Cell 'drink' or 'eat' substances. |
| 9 | Differentiate between phagocytosis and pinocytosis. | Phagocytosis is the engulfing of large particles or cells ('cell eating'), while pinocytosis involves the ingestion of liquids and dissolved substances ('cell drinking'). | Remember 'phago' = eat, 'pino' = drink. |
| 10 | What role do membrane proteins play in cell signaling? | Membrane proteins such as receptors detect signals (e.g., hormones) outside the cell and initiate internal responses, facilitating communication. | Think of them as 'antennae' for the cell. |
| 11 | What is the fluid mosaic model? | The fluid mosaic model describes the cell membrane as a dynamic, flexible structure with a phospholipid bilayer embedded with various proteins, giving it a mosaic appearance. | Visualize a 'mosaic' of proteins in a fluid lipid sea. |
| 12 | Why are cholesterol molecules important in the cell membrane? | Cholesterol modulates membrane fluidity and stability, preventing the membrane from becoming too fluid or too rigid. | Cholesterol acts as a 'fluidity buffer'. |
| 13 | What factors influence the rate of diffusion across the membrane? | Concentration gradient, temperature, molecule size, and membrane permeability influence diffusion rate. | Think 'big, hot, and gradient' for faster diffusion. |
| 14 | How does temperature affect membrane fluidity? | Higher temperatures increase membrane fluidity, making the membrane more flexible; lower temperatures make it more rigid. | Think 'hot and flexible' versus 'cold and stiff'. |
| 15 | What is the significance of selective permeability in the cell membrane? | Selective permeability allows the cell to control its internal environment by regulating which substances enter or exit, maintaining homeostasis. | Membrane as a 'security gate'. |
| 16 | Describe the process of water movement during osmosis when a cell is placed in a hypertonic solution. | Water moves out of the cell into the hypertonic solution, causing the cell to shrink (crenation in animal cells, plasmolysis in plant cells). | Cell loses water to a 'more concentrated' environment. |
| 17 | What is the difference between endocytosis and exocytosis? | Endocytosis brings substances into the cell via vesicles, whereas exocytosis expels substances out of the cell. | 'In' vs. 'out' processes. |
| 18 | Give an example of active transport in human physiology. | The sodium-potassium pump in nerve cells is an example, maintaining the resting potential essential for nerve impulses. | Fundamental for nerve signaling. |
| 19 | What is pinocytosis often called, and what does it involve? | Pinocytosis is often called 'cell drinking' and involves the nonspecific ingestion of liquids and dissolved solutes into small vesicles. | Think 'cell sipping'. |
| 20 | How does the structure of membrane proteins facilitate their function? | Membrane proteins have specific shapes and regions that enable them to bind ligands, transport molecules, or transmit signals across the membrane. | Shape determines function. |
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