bio cell membrane pt 1

fluid mosaic model

cell membrane = flexible, consists of proteins scattered through membrane and molecules can move around

what does it mean that the cell membrane is selectively permeable?

it lets some substances (small, nonpolar) through but not others (large, polar)

passive transport

doesn’t need energy, moves down concentration gradient, can involve transport proteins

active transport

needs energy, moves up the concentration gradient, involves transport proteins

osmosis

water diffuses from area of high to low water concentration

what happens to animal cells in a hypertonic solution

the cells shrink and are crenated

what happens to animal cells in a hypotonic solution

the cells expand and burst (cytolysis)

what happens to plant cells in a hypertonic solution

vacuole shrinks, chloroplasts are in the center (plasmolyzed)

what happens to plant cells in hypotonic solution

cell pushes on wall, wall pushes back with turgor pressure (ideal situation)

what is the relationship between surface area to volume ratio

as a cell gets larger, the surface area to volume ratio decreases; there is less surface to get nutrients in the cell

how to nerve cells work

dentrites recieve the signals from neurons, the axon sends the signal away

purpose of facilitated diffusion

allow charged, polar molecules throughf

facilitated diffusion

done by protein channels not using energy, moving from high to low concentration

endocytosis

active transport of large substances into transport vesicles to outside the cell

phagocytosis

cell eating

phinocytosis

cell drinking

receptor-mediated endocytosis

receptors bind to specific substances

exocytosis

moves large amounts of substances out of the cell using vesicles

how does the sodium-potassium pump work

sodium leaves the cell and potassium enters using energy

endomembrane system

RER produces proteins and SER produces phospholipids, transported to Golgi in vesicle, then moves to cell membrane in another vesicle, membrane fuses and releases the products outside the cell

structure of a phospholipid

has a hydrophilic head that faces out and hydrophobic tails that face in