Membrane Transport Flashcards
(17 cards)
True or False: small molecules are always easier to cross the lipid bilayer of a liposome
than larger molecules.
True
Which major ion has higher concentration inside the cell than outside?
Potassium (K)
True or False: Transport mediated by transporters involves
conformational changes in the transport protein to move
molecules across the membrane.
True
A liposome is a synthetic membrane that does not contain
any protein components. Some uncharged, polar molecules
are found to diffuse across these membranes, to varying
degrees. Which of the following has the lowest rate of
diffusion across the artificial membrane?
A. water
B. glucose
C. glycerol
D. ethanol
Glucose
Q: True or False: active transport is only mediated by transporters.
False, requires an input of energy also
True or False: in passive transport, ions always move down their concentration gradient.
False
can small ions pass through aquaporins?
No they have high specificity for water molecules.
what happens if an animal cell is placed in a hypertonic solution?
It will shrivel as water would move out of the cell
How do plant cells resist osmotic swelling?
they have a cell wall to prevent the cell from expanding excessively
How do transporters and channels select which solutes they help move across the membrane?
Channels discriminate between solutes mainly on the basis of size and electric charge;
transporters bind their solutes with great specificity in the same way an enzyme binds its
substrate
What are the differences between
passive and active transporters?
passive transport moves solute along its elctrochem gradient, while active moves solutes against their electrochem gradient.
active is always coupled to a source of energy
What is the function of Na+ pump?
it generates a steep concentration gradient of Na+ across the plasma membrane.
What is the transport direction of Ca2+ pumps?
out side of the cell away from the cytosol
How do uniports differ from
symports and antiports?
they facilitate the passive diffusion of a solute down its concentration gradient, thus making them not pumps.
True or False: Glucose-Na+
symport uses energy from ATP to drive the transport.
False, the electrochemical Na+ gradient drives the transport.
How does glucose uptake and release by gut epithelial cells occur?
Glucose-Na+ symport actively
uptakes glucose at the apical
plasma membrane.
Most sports drinks contain both carbohydrates and salts. The carbohydrates replace glucose
burned during exercise and the salts replace salts lost in sweat. The salt also helps the small intestine absorb glucose. Pick the answer that accurately describes which salt is most
beneficial for glucose absorption.
NaCl, because Na+ is needed for glucose entry.
