cell transpot Flashcards
(29 cards)
What is passive transport?
A way of moving molecules across the cell membrane that does not require energy.
List the forms of passive transport.
- Simple diffusion
- Facilitated diffusion
- Osmosis
What is active transport?
The energy-consuming transport of molecules or ions across a membrane against a concentration gradient.
List the forms of active transport.
- Protein-mediated active transport
- Exocytosis
- Endocytosis
What can pass through a phospholipid bilayer?
Only molecules that are ‘accepted’ in the inner hydrophobic region, such as small, uncharged molecules and hydrophobic or lipid-soluble molecules.
What is diffusion?
The movement of particles from an area of higher concentration to lower concentration.
What factors affect the rate of diffusion?
- Temperature
- Particle Size
- Concentration
- Distance
- Surface area
What is simple diffusion?
The unaided movement of molecules or ions across a semi-permeable membrane from an area of high solute concentration to low solute concentration.
What is dynamic equilibrium?
A state of balance when the amount of a substance entering a cell equals the amount leaving.
What is facilitated diffusion?
The passive movement of molecules loosely bound to proteins through the cell membrane from an area of high solute concentration to low solute concentration.
What types of proteins are involved in facilitated diffusion?
- Carrier proteins
- Channel proteins
What is osmosis?
The passive movement of water molecules across a selectively permeable membrane from low solute concentration to high solute concentration.
What is osmotic/water potential?
The potential capacity of a solution to lose water molecules through a selectively permeable membrane, depending on solute concentration.
What happens if the osmotic potential is low?
There will be a net flow of water into the cell by osmosis.
What happens if the osmotic potential is high?
There will be a net flow of water out of the cell by osmosis.
What is a hypertonic solution?
A surrounding extracellular solution where solute concentration is higher than that in the cytoplasm.
What is a hypotonic solution?
A surrounding extracellular solution where solute concentration is lower than that in the cytoplasm.
What is an isotonic solution?
When the solute concentration in the extracellular fluid is the same as that inside the cell.
What are the characteristics of active transport?
- Substances are transported against their concentration gradient
- It is a fast process
- Requires cellular energy
- Needs transmembrane protein structures called ‘pumps’
What energy source is used in active transport?
ATP (Adenosine triphosphate) is broken down by the protein.
What is the sodium-potassium pump?
A protein that helps move potassium into the cell and carry sodium out.
What is endocytosis?
The movement of materials into the cell.
What is phagocytosis?
The engulfing of solid material by a cell through extension of the cell membrane.
What is pinocytosis?
The formation of channels by the cell membrane to take in fluid.
