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Questions and Answers
Which type of channel is always open and allows ions to pass through their concentration gradient?
Which type of channel is always open and allows ions to pass through their concentration gradient?
In which type of transport does the substance move from a region of lower concentration to a region of higher concentration?
In which type of transport does the substance move from a region of lower concentration to a region of higher concentration?
What is a key characteristic of selectively permeable membranes?
What is a key characteristic of selectively permeable membranes?
Which type of gated channel opens in response to a change in electrical charge?
Which type of gated channel opens in response to a change in electrical charge?
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What is the primary distinction between passive and active transport mechanisms?
What is the primary distinction between passive and active transport mechanisms?
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Study Notes
Channels
- Leakage channels (passive channels) always allow ions to pass through their concentration gradient.
- Gated channels open under certain conditions:
- Ligand-gated: Receptor and channel are in one, hormones or neurotransmitters open them.
- Mechanically-gated: Open due to mechanical deformation of the membrane (e.g., blood pressure).
- Voltage-gated: Open due to a change in charge (e.g., neurons and muscle tissue).
Selectively Permeable Membranes
- Allow some substances to pass through while preventing others.
Transport Mechanisms
- Passive transport: Requires no ATP (e.g., filtration, diffusion, osmosis).
- Active transport: Uses ATP.
- Carrier-mediated transport: Uses membrane proteins to transport substances.
Concentration Gradients
- Difference in concentration of a substance across a membrane.
- Molecules naturally tend to move from high to low concentration.
Factors Affecting Membrane Permeability
- Size of molecule
- Properties of molecule (polar vs. nonpolar, charged vs uncharged, hydrophobic vs. hydrophilic)
Passive vs. Active Transport
- Passive transport: No energy used; moves substances down their concentration gradient.
- Active transport: Uses energy; moves substances up/against their concentration gradient; requires transport proteins.
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Description
This quiz covers essential concepts related to membrane transport mechanisms, including types of channels, permeability, and transport methods. Explore the differences between passive and active transport and understand how concentration gradients influence the movement of substances across membranes.
