Flashcards in Membranes Deck (25):
What factors affect membrane permeability?
Steroid content - the more steroid that makes up the membrane the less permeable it is
Temperature- an increase in temperature results in an increase in fluidity
What factors effect the rate of diffusion?
Size of particles
Size of membrane
Distance between regions
What is diffusion?
Diffusion is the movement of molecules or ions from a region of high concentration to a region of low concentration
What is facilitated diffusion?
This is a form of diffusion that uses carrier and Chanel proteins to allow faster movement.
I’m facilitated diffusion what do the channel proteins allow entry to?
Charged particles that cannot diffuse easily across the non polar centre of the phospholipid bi layer.
What do the carrier proteins allow transport to?
Larger polar molecules such as sugars and amino acids.
What is osmosis?
Osmosis is the movement of water molecules from a region of high water potential to an area of low water potential through a partially permeable membrane.
What is solute potential?
The measure of the reduction in water potential due to solute molecules being present
The pressure exerted on the cell contents by the cell wall and membrane
What is turgidity?
When water enter the cell via osmosis, filling the cell and pushing the cell membrane against the cell wall
What is plasmolysis?
The opposite of turgidly, when water leaves the cell and the cell membrane is pulled away from the cell wall - the cell becomes flaccid
What is a hypertonic solution?
What is a hypotonic solution?
What is an isotonic solution?
Solution has the same water potential as the cell
What is active transport?
Active transports is the uptake of molecules or ions agains a concentration gradient using energy from respiration (atp)
What is endocytosis?
During endocytosis the cell membrane wraps it’s set around the material and brings it into the cytoplasm in a vesicle. There are two types:
What is phagocytosis?
Solid material is taken into the cell
What is pinocytosis?
When liquid is taken into the cell
What is exocytosis?
Exocytosis is the reverse of endocytosis - taking material out of the cell.
What is the process of endocytosis?
Material is brought into the cell in a vesicle, lysosomes use with the vesicle, emptying their enzymes into it. The enzymes digest the contents and the products are released into the cytoplasm
What is the function of the plasma membrane?
Controls the movements of molecules into and out of the cell
Maintains a difference of concertration of ions / molecules inside and outside the cell
Encourages cell division
Internal membranes allow compartmentalisation
What is the plasma membrane made of?
Span the membrane
Only one layer - top or bottom