Cell Membrane Transport Flashcards
Define passive transport
When no energy is required from the cell to pass through the cell membrane. Substances are moving from an area of higher concentration to an area of lower concentration.
Define active transport
When substances require energy to pass through the cell membrane, often because they’re moving from an area of low concentration to an area of high concentration (up the gradient)
Define concentration
The number of particles of a substance per unit of volume. More particles means a higher concentration.
Describe diffusion
The movement of a substance due to a difference in concentration. Happens w/out help from other molecules.
What are the three types of passive transport?
diffusion, osmosis, and facilitated diffusion
What kind of substances pass through using diffusion? Why?
Small, hydrophobic molecules (like oxygen and CO2) can squeeze between lipid molecules by simple diffusion.
Describe osmosis
The diffusion of water molecules. Moves from area of high concentration to low concentration. Water moves in or out of the cell until its concentration is the same on both sides of the membrane. Has to occur across a semipermeable membrane (like the plasma membrane).
Describe facilitated diffusion
Transport proteins help diffusion.
What kind of substances use facilitated diffusion?
hydrophilic molecules, charged ions, relatively large molecules
What are the different types of transport proteins?
Channel proteins and carrier proteins
What do channel proteins do?
Form tiny holes/pores in the membrane which allows water molecules and small ions to pass through the membrane without touching the hydrophobic tails of the lipid molecules.
What do carrier proteins do?
Bind with specific ions or molecules. Binding makes protein change shape as it carries ions/molecules across the membrane.
Define solution
A mixture of a solvent (usually H2O) and a solute (the thing that is dissolved, like sugar or salt)
Define isotonic
solutions of equal concentrations of solutes.
Which of the following can pass through the cell membrane: Na+, Cl-, O2, a protein, H2O, glucose.
O2 and H2O
