transport across cell membranes - the basics Flashcards
what does the cell membrane do and for that reason what are they?
- controls what enters and leaves and so are selectively permeable
describe how a cell membrane looks:
what type of protein is in a cell membrane and what are the 2 types?
what is its job?
- consists of a phospholipid bilayer with phosphate heads and fatty acid tails. the heads are hydrophilic and are in contact with water and the tails are hydrophobic protected from water
- transport protein, extrinsic and intrinsic
- transport molecules from 1 side of the membrane to the other
what 2 things does simple diffusion occur in and why?
SIMPLE = SMALL
- liquids and gases as they have kinetic energy
what is used in facilitated diffusion?
what is moved in by this diffusion
LARGE AND CHARGED
how do protein channels work?
THINK OF A STREAM
how do carrier proteins work?
VERY INDUCED FIT
- proteins to transport molecules
- ions and polar molecules
- form long tubes filled with water to only allow water soluble ions to pass through the membrane
- will bind to a molecule and that causes a change of shape in the carrier protein which causes the molecule to be released to the other side of the membrane
what is active transport?
2 things needed?
how are carrier proteins selective?
- movement of molecules an ions from an area of lower onc to an area of higher conc against the conc gradient
- ATP and carrier proteins
- only certain molecules can bind with the carrier protein
what proteins do each transport use
diffusion
facilitated
active
why do we need ATP for active transport?
what dictates being carried in by co transport OOPS NOT FACILITATED SORRY
- NONE
- protein channels and carrier proteins
- carrier proteins
- we need energy to change the shape of the carrier protein
- large and charged
explain how the transport of sodium ions is involved in the absorption of amino acids by epithelial cells:
