Questions and Answers
Why are cell membranes semi-permeable?
Cell membranes are semi-permeable, which means molecules can move through them. This is important for cells to survive. Osmosis is where solvent molecules (usually water) move from one side of a cell membrane to the other.
Why are cell membranes selectively permeable?
It only lets certain things in and out. The structure of the phospholipid bilayer prevents random things from drifting through, and proteins act like doors, letting the right substances in and out.
What types of particles do not diffuse through membranes well?
Many large molecules, such as glucose and other sugars, cannot cross the membrane.
What does hypotonic mean?
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What does isotonic mean?
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What does hypertonic mean?
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What is active transport?
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What is passive transport?
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What is facilitated transport?
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What are the processes of endocytosis?
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What is the process of exocytosis?
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Describe the structure of the plasma (cell) membrane.
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What is osmosis?
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What does hypertonic mean in relation to a solution?
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What does hypotonic mean in relation to a solution?
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Study Notes
Cell Membrane Characteristics
- Cell membranes are semipermeable, allowing selective movement of molecules essential for cell survival.
- Osmosis involves the movement of solvent molecules, primarily water, across a cell membrane.
Selective Permeability
- Cell membranes only permit specific substances to enter or exit.
- The phospholipid bilayer structure restricts indiscriminate passage, while membrane proteins function as selective channels.
Particle Diffusion
- Certain small molecules, like hydrocarbons and oxygen, can easily diffuse through the membrane.
- Larger molecules, including glucose and other sugars, are restricted from passing through directly.
Solution Concentration Terms
- Hypotonic: A solution with a lower concentration of solute compared to another solution.
- Isotonic: Two solutions with equal concentrations of solute.
- Hypertonic: A solution with a higher concentration of solute compared to another solution.
Transport Mechanisms
- Active Transport: Requires energy to move materials against a concentration gradient through the membrane.
- Passive Transport: Occurs spontaneously without energy input, allowing substances to move across the membrane.
- Facilitated Transport: Utilizes integral membrane proteins for the movement of materials down a concentration gradient from high to low concentration.
Endocytosis and Exocytosis
- Endocytosis: Engulfing substances or particles from outside the cell to bring them inside via the cell membrane.
- Exocytosis: A process for particles that are too large to pass through protein channels, where the cellular membrane surrounds and releases materials by fusing with the membrane.
Plasma Membrane Structure
- Composed of a phospholipid bilayer arranged back-to-back, providing a dynamic and flexible barrier.
Osmosis and Water Movement
- Osmosis: The diffusion process specifically referring to the movement of water through a selectively permeable membrane.
- Hypertonic: Describes a condition with high solute concentration and low water potential.
- Hypotonic: Refers to a situation with low solute concentration and high water potential.
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Description
This quiz covers key concepts related to cell membranes, focusing on their semi-permeable and selectively permeable nature. Understanding these properties is crucial for grasping how cells interact with their environment and maintain homeostasis. Review these flashcards to enhance your knowledge of cellular biology.
