Cells Flashcards
(339 cards)
Osmotic pressure
Minimum amount of pressure required to stop the diffusion of pure water across the membrane. If a vessel is divided into two Chambers and pure water is placed into one chamber while a solution such as sugar water is placed in the other chamber the water level will rise on the side of the greater solute concentration therefore the diffusion of water will continue in this direction until the pressure becomes too great The water will have moved from high to low water concentrations.
Passive transport
The movement of substances across the cell membrane without the input of energy.
Entropy
Unavailable energy disorder
Nonpolar molecules
Hydrophobic electrons are shared equally and there is no resulting charge
Polar molecules
Have either a positive or negative charge
Examples of nonpolar molecules
Oxygen gas carbon dioxide an uncharged lipids are not repelled by the hydrophobic interior of the membrane
What are forms of passive transport
Simple diffusion osmosis and facilated diffusion
Osmosis
The passive transport of water across the membrane most polar molecule cannot use simple diffusion but water molecules are small enough to slowly squeezed between the phospholipids
What can water use to channel proteins to increase the rate of osmosis
Aguaporins
When proteins are used to transport substances down their concentration gradients
Facilitated diffusion
Gradient
Increase or decrease
Facilitated diffusion
Molecules diffuse across the plasma membrane with assistance from membrane proteins such as channels and carriers a concentration gradient exists for these molecules so they have the potential to diffuse into or out of the cell by moving down it.
Large polar and or charged substances require shielding from the interior of the membrane and they may use
Channel or Carrier proteins to assist in their transport
Osmosis does not require what to be driven by the difference in solute
ATP
Active transport
Energy is used to move solutes into or out of the cell
During what transport are substances pumped against their concentration gradients from areas of low to high concentration
Active transport
Active transport is required for processes such as
The maintenance of a membrane potential and the uptake of glucose by intestinal cells even between meals
The pumping of solutes by a carrier protein is directly coupled to the hydrolysis of ATP
Primary me active transport
Relies on ATP to generate an electrochemical gradient and it is this grattent that directly drives the active transport of a different solute
Secondary active transport
As one solute moves down as graduate another is
Pumped up its gradient
When both solutes move in the same direction it is called
Symport
When solutes move in opposite direction it is called
Antiport
Endocytosis and exocytosis are types of
Active transport that employ vesicles to import or export substances. they do not necessarily move solutes up their concentration gradient
Endocytosis
Is cellular process in which substances are brought into the cell