Cell Transport Flashcards
What is the fluid-mosaic model?
The currently accepted model of plasma membrane structure, depicting a fluid phospholipid bilayer with embedded proteins.
What are the structural components of the plasma membrane?
Phospholipid bilayer, cholesterol, glycoproteins, glycolipids, and membrane proteins.
What is the primary function of the plasma membrane?
To regulate what can enter and exit the cell, which helps the cell to maintain homeostasis.
What do phospholipids form?
A bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward.
What role does cholesterol play in the plasma membrane?
It adds strength and stability to the membrane’s fluidity.
What are integral proteins?
Proteins that span the entire membrane.
What are peripheral proteins?
Proteins attached to either the intracellular or extracellular side of the membrane.
What is the function of glycoproteins?
They are involved in cell-to-cell recognition.
What is diffusion?
The movement of molecules from an area of higher concentration to an area of lower concentration.
What is osmosis?
The facilitated diffusion of water across a differentially permeable membrane.
What happens to cells in an isotonic solution?
They neither gain nor lose water.
What happens to cells in a hypotonic solution?
They gain water.
What happens to cells in a hypertonic solution?
They lose water.
What is facilitated diffusion?
A passive transport process involving channel proteins moving substances from higher to lower concentrations.
What is active transport?
The movement of substances against their concentration gradient using energy and a carrier protein.
What is exocytosis?
The process by which larger substances are exported from the cell.
What is endocytosis?
The process by which larger substances are taken into the cell.
How do animal cells react in isotonic solutions?
Water moves equally into and out of the cell; there is no net movement of water.
How do plant cells react in hypotonic solutions?
The central vacuole fills up, and the cell membrane presses against the cell wall, creating turgor pressure.
What is lysis?
The bursting of an animal cell due to excessive water intake.
What is crenation?
The shrinking of an animal cell in a hypertonic solution.
What is plasmolysis?
The process where the plant cell membrane shrinks away from the cell wall in a hypertonic solution.
What is the sodium-potassium pump?
An example of active transport that moves sodium out of and potassium into the cell.
What is the role of channel proteins?
They assist with the movement of charged or polar molecules across the plasma membrane.
What is the difference between facilitated diffusion and active transport?
Facilitated diffusion does not require energy and moves substances down their concentration gradient, while active transport requires energy and moves substances against their gradient.
What happens to the level of solution on each side of the membrane when water moves from side B to side A?
The level will rise in side A and lower in side B.
How does a plant cell respond to a hypotonic environment?
It fills with water, creating turgor pressure, which is the preferred state.
What is the permeability of the plasma membrane to small, nonpolar molecules?
They tend to pass freely across the plasma membrane.
What is the role of carrier proteins?
They assist with the active movement of molecules against their concentration gradient.
What is the result of a 2% salt solution compared to a 4% salt solution?
The 2% salt solution is hypotonic relative to the 4% salt solution.
What is the result of a 4% salt solution compared to a 2% salt solution?
The 4% salt solution is hypertonic relative to the 2% salt solution.
What is isotonic relative to a 2% salt solution?
A solution with 2% solute.
What is the primary energy source for the sodium-potassium pump?
ATP.
Which process does NOT require energy?
Diffusion, osmosis, and facilitated diffusion.
What is the term for the bursting of an animal cell?
Lysis.
In which solution does an animal cell always take in water?
Hypotonic.
Which ion is often actively transported across plasma membranes?
Sodium ions.
