transport across cell membranes Flashcards
what is the role of cholesterol?
restricts the movement of other molecules making up the membrane.
what are the five different movements across the cell membrane
-co transport
-osmosis
-facilitated diffusion
-simple diffusion
-active transport
what is simple diffusion?
the movement of substances from an area of high concentration to low concentration.
down it concentration gradient until it has reached its equilibrium.
what scenario is simple diffusion used in. within a cell membrane.
when the substance is non polar, water insoluble and lipid soluble.
what factors affect diffusion.
temperature, concentration gradient and surface area
why is the cell membrane referred as the fluid mosaic model?
fluid- the phospholipids are able to move within the membrane.
mosaic-it is made up of many different componants.
what is meant by concentration gradient
the difference in concentration between one area and another.
why is facilitated diffusion used in the cell membrane.
if the substance is large
polar
water soluble
what is a protein carrier
change its shape so that its complimentary to the molecule.
allows the molecule to bind onto the carrier protein allowing it to
diffuse to the other side of the membrane.
what is a protein channel.
hydrophilic pathway which allow for water molecules and ions to diffuse through.
what happens when temperature or concentration affect the cell membrane
-the cell membrane is damaged
-the proteins in the phospholipid bilayer denature.
-this mans that the cell membrane becomes really fluid.
what is the definition of osmosis
the movement of water molecules from high water potential to low water potential through a partially permeable membrane. down its concentration gradient.
what is water potential.
pressure created by water molecules
what is the water potential of pure water
0
what does it mean when the water potential is low.
there is more solutes within the solution.
