Chapter 4 Part 2: Osmosis Flashcards
Define diffusion.
The spontaneous movement of a substance from a region where it is more concentrated to a region where it is less concentrated .
Define concentration gradient.
A solute is more concentrated in one region than in a neighboring region.
What factors affect the rate of simple diffusion?
Temperature, size of molecule, type of medium.
How do cells maintain concentration gradients?
By consuming the substance as they diffuse or by producing more of the substance as they diffuse out.
Define osmosis.
Simple diffusion of water across a selectively permeable membrane.
What factors affect the rate of osmosis?
Temperature, because a faster temperature a faster reaction.
the distance the molecules have to move across, so the more distance between the two sides the slow the rate of osmosis.
Concentration of water potential and lower water potential sides
Define turgor pressure?
It is the resulting force of water against the cell wall.
Compare diffusion and osmosis.
Diffusion is the spontaneous movement of a substance from a region where it is more concentrated to a region where it is less concentrated. Osmosis is the simple diffusion of water across a selectively permeable membrane . Both move across water.
Define facilitated diffusion.
It is a form of passive transport in which a membrane protein assists the movement of a polar solute along its concentration gradient.
Define active transport.
Transport protein moves substances against its concentration gradient; requires energy input, often from ATP.
Compare active transport and facilitated diffusion.
Facilitated diffusion is substances to which the membrane is not permeable across the membrane with assistance of transport proteins.
Active transport is transport protein moves substances against its concentration gradient requires energy input, often from ATP.
They both use proteins to transport substances.
Define endocytosis.
Allows cells to engulf fluids and large molecules and bring them into the cell.
Define phagocytosis?
The cell captures and engulfs large particles, such as debris or even another cell.
Define Exocytosis.
The opposite of endocytosis, uses vesicles to transport fluids and large particles out of cells.
Explain how the sodium-potassium pump is important to the normal functioning of the cell.
This pump is a protein embedded in the cell membrane. It uses energy released in ATP hydrolysis to move potassium ions into the cell. In each case, the ions move from where they are less concentrated to where they are more concentrated.
