cell membrane Flashcards
What
§Cells need an inside & an outside… useparate cell from its environment ucell membrane is the boundary
cells need to carry things in and out
what is semi-permeable
cell membrane controls what gets in or out
needs to allow some but not all materials to get through
fats and oils can pass through directly
what do protein channels do
allow substances in and out
specific to materials
aquaporin
salt channel
helix shape
how can channels be hydrophilic
The outside layer of the channel had to be hydrophobic to fit in hydrophobic region. the inside has to hydrophilic to let stuff through
What is diffusion
The movement of molecules from high to low concentration with out energy until equilibrium
Simple diffusion explain please
directly through membrane, no channel needed
what is facilitated diffusion
move from high to low through a protein channel
no energy needed
what is active transport
Cells may need to move substances from low to high concentration
protein pump is needed
requires ATP
Describe Osmosis
Movement of water across membrane
diffusion of water from high to low concentration across a semi-permeable membrane
What happens in fresh water
normal water
salt water
lysed turgid
high concentration of water around cell. cell gains water and burst. best solution=contractile vacuole.
normal Flaccid
no problem:
diffusion of water in=diffusion of water out
shriveled plasmolyzed
very low concentration of water around cell. cell loses water. solution-pinocytosis.
isotonic
hypertonic
hypotonic
cell in equilibrium
cell shrivel
lysed
phagocytosis
endocytosis
pinocytosis
exocytosis
intake of large amounts of food
intake of large amounts of molecules
intake of large amounts of liquids
bulk transport of wastes to outside of cell.
when cell volume increases what happens to surface area to volume ratio
it decreases and becomes less effecient
