cell membrane transport Flashcards
two ways that substances can be moved across a membrane
PASSIVE transport and ACTIVE transport
what form of cell membrane transport requires energy
active
passive transport is chill and doesn’t care, no energy
diffusion:
the movement of PARTICLES from a region of HIGH concentration to a region of LOW concentration
the difference in concentration between two regions:
concentration gradient
in diffusion, particles move ___ their concentration gradient
down/along
osmosis:
the diffusion of WATER from an area of HIGH concentration to LOW concentration
WHAT from the extra cellular fluid and from the inside of the cell diffuses freely through the cell membrane.
water
the direction of osmosis depends on:
the concentration of water molecules on either side of the cell membrane
isotonic solution
equal movement of water into and out of cells (ideal for ANIMALS)
hypertonic solution (PLASMOLYSIS)
less water, more solute
WATER FLOWS OUT, CELL SHRIVELS
ideal for plants
hypotonic solution (LYSIS)
more water, less solute
WATER MOVES INSIDE, CELL BURSTS
facilitated diffusion:
cell membrane is filled with proteins that act as CHANNELS/CARRIERS that help in the passive transport of molecules into or out of cell
facilitated diffusion needs ___ to make way across
PROTEIN
channel proteins form a:
passageway for substances
when channel protein passageway opens, it can transport:
CHARGED PARTICLES or SMALL POLAR MOLECULES across cell membrane
a charged particle can only pass through the channel if:
it has the right charge
a positively charged channel can only transport a negatively charged ion
aquaporins:
type of channel protein that facilitate the movement of water through the membrane
carrier proteins (SIZE AND SHAPE SPECIFIC):
bund specific molecules to be transported and conformational changes to transfer bound molecule across membrane
examples of carrier proteins
glucose, amino acids
carrier proteins can passively and actively transport molecules:
from area of HIGH concentration to area of LOW concentration
the sodium-potassium pump is:
a cell membrane protein
(driven by cell metabolism, ATP)
actively pumps sodium and potassium against concentration gradients
when is bulk membrane transport used
when substances are too big or too polar to cross the lipid bilayer
requires energy
in bulk membrane transport, the cell membrane:
folds upon itself to create a membrane enclosed, bubble like sac or vesicle
endocytosis:
the cell membrane folds inward and traps a small amount of matter from the extra cellular fluid and brings into cell
pinocytosis (ENDOCYTOSIS):
cell DRINKING. liquid droplets are engulfed by cells
phagocytosis (ENDOCYTOSIS):
cell EATING. solid particles are engulfed by cells
Exocytosus (BULK MEMBRANE TRANSPORT):
a vesicle from inside the cell moves to the cell surface, fuses with the cell membrane and releases its contents
Exocytosis (BULK MEMBRANE TRANSPORT) is important in cells that are:
responsible for releasing cell-manufacturing products
ex. cells of pancreas secrete insulin by exocytosis
tonicity:
measure of relative concentration of SOLUTE particles in or outside of a semi permeable membrane
what determines the direction and extent to which water moves by osmosis
tonicity (concentration ratio)
once the amount of water entering and leaving the cell is the same, ____ is reached
dynamic equilibrium
a HYPOtonic solution contains
LESS solute, MORE water than cell.
water moves into cell by osmosis
if a plant cell is placed in a hypotonic solution, the plant cell will become:
TURGID due to an increase in turgur pressure.
when an animal cell is placed in a hypotonic solution, the cell will LYSE (burst) because
the animal cell lacks a cell wall, isn’t resistant to pressure
a hypertonic solution contains
MORE solute and LESS water than cell.
water moves out of cell by osmosis
turgor pressure decreases and plasnolysis is caused
plasmolysis:
cell membrane separates fork the cell wall
both animal and plant cells will shrivels in a:
HYPERtonic solution
red blood cells are normally suspended in:
plasma
a liquid containing salts, proteins, other solutes
isotonic solution:
solute concentration is the same inside and outside of cell
cell size stays the same
plant cells would become __ in an isotonic solution
flaccid
glycoprotein vs glycolipid
glycoprotein: carbohydrate-attached PROTEIN (bigger thing)
glycolipid: carbohydrate-attached LIPID (smaller component)
