Cell membranes and transport in cells Flashcards
List the components making up a cell membrane
Phospholipids, proteins, glycoproteins and glycolipids.
Cholestrol may also be present in cell membranes where it restricts the movement of other molecules making up the membrane.
What is the fluid mosaic model?
The parts making up the membrane are free to move fluidly throughout the membrane.
List ways which substances can move across the cell membrane
Simple diffusion, facilitated diffusion, osmosis, active transport and co-transport.
What is simple diffusion?
Movement of small substances directly through the phospholipid bilayer.
What is facilitated diffusion?
Movement of substances through the membrane using carrier proteins and channel proteins
What is osmosis?
Movement of water directly through the phospholipid bilayer
How does water move?
From a less negative to a more negative water potential
What affects water potential?
The amount of dissolved substances in the water
Define hypertonic
The concentration of the solution is higher than that of the cell
Define hypotonic
The concentration of the solution is lower than that of the cell
Define isotonic
The concentration is the same in both solutions being compared
What is active transport?
The movement of substrances through the membrane via carrier proteins. Active transport uses energy which is transferred by the hydrolysis of ATP.
How are cells adapted for rapid transport across their internal or external membranes?
An increase in surface area or an increase in the number of protein channels and carrier molecules in their membranes.
