Transport Across Membrane Flashcards
What happens if tertiary structure of carrier protein changes?
- Facilitated diffusion/active transport can’t occur
- Because binding site has changed shape so no longer complimentary
What happenes if aerobic respration is inhibited?
Active transport cant occur as there’s less ATP but other transport continues until equilibrium is reached
What is endocytosis?
Cell surface membrane is ‘pulled’ inwards to create vesicle + requires breakdown of ATP
What is active transport? (3)
- Transportation of molecules across membrane against the concentration gradient
- By ATP (which is produced through respiration + provides energy through ATPhydrolase)
- ONLY uses carrier proteins that has specific shape with complimentary binding site
What is exocytosis? (2)
Uses Golgi vesicles to move large quantities of molecules from indside to outside of cell + enzymes/glycoproteins to secrete proteins with use of ATP
If water potential decreases the pressure…?
Decreases as pure water has 0kPa
What pressure/water potential does pure water have?
0 kPa/highest water potential
What is osmosis?
Net movement of water molecules from a higher water potential to lower water potential through a partially permeable membrane
Factors affecting rate of diffusion? (4)
- Temperature
- Surface area
- Concentration gradient
- Diffusion distance
What is facilitated diffusion?
How would this look on a graph? Why?
Proteins that help molecules pass through phospholipid bilayer down concentration gradient
- Plateaus at lower rate than simple because there are fewer specific carrier proteins which is the limiting factor
What’s Ficks law?
Surface area X conc. gradient
—————————————- = RoD
Diffusion distance
What is simple diffusion?
Net movement of molecules from an area of higher conc. to a lower conc.
Name and describe five ways substances can move across the
cell-surface membrane into a cell? (5)
- (Simple) diffusion of small/non-polar molecules down a concentration gradient
- Facilitated diffusion down a concentration gradient via protein carrier/channel
- Osmosis of water down a water potential gradient
- Active transport against a concentration gradient via protein carrier using ATP
- Co-transport of 2 different substances using a carrier protein/cotransport protein
Function of aquaporins?
Type of channel protein specific to water
Function of glycoproteins?
Important for cell recognition
