Cell Membrane Flashcards
Explain the functions of the cell membrane
A phospholipid bilayer that is selectively permeable, regulating with goes in and out of the cell though different aqueous compositions inside and outside the cell
Define osmosis
The diffusion of water molecules across a selectively permeable membrane from a low solute concentration to a high solute concentration.
The plasma membrane is highly permeable to which substances?
- Oxygen
- CO2
- Fatty acids
- Alcohol
- Steroids
List two types of passive transport
- Diffusion
- Filtration
Why is diffusion vital in biological systems?
Because CO2 builds up in cells, diffuses across the membrane, into interstitial fluid and then blood
How does movement occur within the concentration gradient?
Movement occurs down the concentration gradient, from high concentration to low concentration
Define simple diffusion
Materials move through the membrane without the help of transport proteins
Define facilitated diffusion
Materials use protein channels or carriers to diffuse across the plasma membrane
Define tonicity
The term used to describe the effects of osmotic pressure on cells
Explain isotonic solution
There is no net flow of water into or out of the cell
Explain hypertonic solution
Water flows out of cell as cell has lower concentration of solutes
Explain hypotonic solution
Water flows into cell as cell has higher
concentration of solutes
Define active transport
Transportation of materials across the plasma membrane that does not require a concentration gradient, rather uses ion pumps that require energy (ATP)
Define endocytosis
Entry into the cell
Define exocytosis
Exiting from the cell
