Chapter 3.3 Flashcards
What is Diffusion?
the tendency of atoms, molecules, and ions in a liquid or air to move from areas of higher concentrations to areas of lower concentrations
Concentration Gradient
A difference of concentration between two different areas
Diffusional Equilibrium
Random movements continue, but there is no further net movement, and the concentration of a substance remains uniform through the solution
Diffusion can only occur if
the cell membrane is permeable to that substance and a concentration gradient exists such that the substances is at a higher concentration on one side of the membrane or the other
What smalled solutes are not lipid-soluble?
Ions of sodium, potassium, and chloride, may diffuse through specific protein channels in the membrane
Facilitated Diffusion
This type of movement follows the concentration gradient, and because it requires membrane proteins it is considered to be “helped”
Facilitated diffusion can move
molecules only down a concentration gradient
What is Osmosis?
The movement of water across a selectively permeable membrane into a compartment containing solute that cannot cross that membrane.
One can think of impermeant solute as
solute that is “trapped” on one side of the membrane.
Osmotic Pressure
This ability of osmosis to generate enough pressure to lift a volume of water
Isotonic
Any solution that has the same osmotic pressure as body fluids
Hypertonic
Solutions that have a higher osmotic pressure than body fluids.
What happens if cells are put in a Hypertonic solution?
Water moves by osmosis out of the cell into the surrounding solution, and the cell shrinks
What happens if cells are put in a Hypotonic solution?
Has lower osmotic pressure than body fluids, gain water by osmosis and swell.
Filtration
Another process that foces molecules through membranes by exerting pressure.
What is Active Transport?
Movement against a concentration gradient. It requires energy, which comes from ATP molecules that split during the process of cellular metabolism.
What are “pumps”
Because these carrier transport substances from regions of lower concentration to regions of higher concentration
Endocytosis
conveys molecules or other particles too large to enter a cell by other means to the inside in a vesicle that forms from budding inward of a section of the cell membrane
Pinocytosis
Cells take in tiny droplets of liquid from their surroundings, as a small portion of cell membrane indents.
Phagocyotsis
Similar to pinocytosis, but the cell takes in solids rather than liquids.
Phagocytes
They can take in solid particles such as bacteria and cellular debris. When a particles outside the cell touches the cell membrane, a portion of the membrane projects outward and draws it inside the cell
What is a Phagosome
The part of the cell’s membrane surrounding the particle then detaches the cell’s surface, forming this vesicle
What is a Phagolysosome?
When a lysosome joins a phagosome, it forms this
What is Receptor-Mediated Endocytosis
Moves very specific types of particles into the cell. It uses protein molecules that extend though the cell membrane and are exposed on its outer surface.
