3: movement into and out of cells Flashcards
what is the role of membranes in the cell?
- allows chemical reactions on the surface
- enables cells to receive hormone messages
- forms and controls an ionic gradient
what is the phospholipid bilayer?
- hydrophobic and hydrophilic lipid molecule layers that float in a fluid
list the components of the membrane
- phospholipid bilayer
- proteins
- cholesterol
- glycolipids and glycoproteins
what is diffusion?
the net movement of solutes across a partially permeable membrane from a region of high concentration to a region of low concentration due to the random movement of particles
what kind of transport is diffusion?
passive transport- does not require energy
what are the types of diffusion?
- simple diffusion
- facilitated diffusion
what are the factors affecting the rate of diffusion across the membrane? [6]
- steepness of the concentration gradient
- temperature
- surface area
- distance
- nature of mol/ion [size and polarity]
- solubility of lipid/fat
why can’t large, polar molecules pass through the ppm?
the size and charge of these molecules make it too difficult for them to pass through the non-polar region without the use of proteins
where do charged ions pass through the ppm?
carriers made by protein molecules
what is facilitated diffusion
- diffusion but through a protein channel
- not energy dependent
what is the difference between carrier proteins and protein channels?
- protein channels work with the conc. gradient
- carrier proteins work against the conc. gradient
what is osmosis?
the net movement of water molecules from a region of high water potential to a region of low water potential
what is water potential?
tendency of water to move from one place to another
what is the water potential of pure water?
0
what happens when equilibrium is reached in osmosis?
there will be no net movement of water
describe the osmosis in an animal cell if:
- water potential of solution is high
- water potential of solution is low
- cell swells and bursts
- cell crenates
describe the osmosis in a plant cell if:
- water potential of solution is high
- water potential of solution is low
- water pont. increases inside until equilibrium is reached (cell becomes turgid)
- plasmolysis happens and there is no wall pressure (flaccid)
what is plasmolysis?
when the cell membrane and vacuole shrinks and starts to pull away from the cell wall
what is active transport?
movement of solutes across the ppm using carrier proteins
what does active transport require?
- ATP to help change the shape of carrier proteins
what is the Na K pump?
carrier proteins that pumps out Na ions and allows in K ions
where is the Na K pump found?
found at the surface of cell membranes
what does the Na K pump do?
controls the osmotic balance of cells
what is bulk transport?
transportation of large molecules
