Transport Specifics Flashcards
When does simple diffusion into the cell through the lipid bilayer occur?
when solute concentrations are greater on the inside of the cell than on the outside
What is facilitated diffusion through a specific transporter?
Passive diffusion with the use of a transporter protein that will only allow specific molecules/ions into the cell
What is facilitated diffusion through a nonspecific transporter?
passive diffusion with the use of a transported protein that will let any molecule/ion into the cell
What is osmosis?
the moevement of water into and out of the cell based on a concentration gradient
What are aquaporins used for?
they selectively conduct water into and out of the cell during osmosis while preventing other solutes or ions from entering or exiting the cell
What two ways can water move into and out of the cell during osmosis?
through the lipid bilayer and through an aquaporin
How is the osmotic relationship between cells and their environment determined?
by the relative concentrations of the solutions on either side
What does isotonic mean?
the water concentration is equal inside and outside of the cell
When a cell is isotonic with its environment, rates of diffusion are _________ in both directions
equal
what does hypotonic mean?
Higher solute concentration inside of the cell than outside
in a hypotonic scenario, net water diffusion is _______ the cell
into
WHat occurs during the diffusion of water into a hypotonic cell?
the protoplast swells, and pushes tightly against the wall, the wall prevents it from bursting
What does hypertonic mean?
solute concentrations are greater iutside of the cell than inside the cell
when a cell is hypertonic, net water diffusion is _____ the cell
out of
what is plasmolysis, when does it occur?
when water diffuses out of the cell and shrinks the protoplast away from the cell wall. This occurs when a cell is hypertonic with its environment.
Where do active transport mechanisms use energy from?
typically from ATP (primary) and from ion gradients (Secondary)
What is the saturation effect for active transport mechanisms?
can only increase transport until all binding sites are used, in which case transport will plateau
Why is active transport highly specific?
Bacteria like to use sugar as an energy source, but some sugars work better than others/ some cant be used.
why is it important for active transport to be regulated?
Bacteria want the ability to use a wide variety of sugars as food sources, but it is energetically costly to express all transporters all of the time
______________ and _____________ are coupled transport systems in which energy released by moving a driving ion from a region of high concentration to low concentration is harnessed and used to move a solute against its concentration gradient
antiport and symport
Antiport and Symport are ________ active transport mechanisms
secondary
What does ABC stand for in ABC transport
ATP binding cassette
What happens in ABC transporters
solutes are internalized due to ATP hydrolysis
What are the steps of ABC transport
- solute binding protein binds to whatever needs to be brought inside of the cell
- solute binding protein can associate with membrane-spanning domains
- ATP binding domains bind ATP and hydrolyze it into ADP
- Solute comes into the cell using energy from ATP hydrolysis
What do two membrane-spanning domains form?
a pore
How many ATP binding domains are there in a pore?
two ATP binding domains
