Membranes And Fludity Flashcards
What is cell membrane made out of
Proteins
Carbohydrates
Cholesterol
Phospholipid
Describe the phospholipid bilayer
Forms a barrier to certain molecules
Gives membrane fluidity hydrophilic head is on outside and hydrophobic tails on the inside
Allows passage of non-polar substances , lipid soluble but blocks polar and large molecules
Describe the extrinsic proteins
These are the proteins which are partially outside the cell membrane
Some proteins act as enzymes on the surface of cells
Some act as receptors for hormones
Describe carrier proteins
Act as transport for polar or large substances that can’t pass through phospholipids.
What’s a protein channel
Intrinsic proteins with hydrophilic linings which allow passage of polar molecules that can’t pass through the lipids
Explain glycoproteins and glycolipids
It’s a carbohydrate chain attached to protein or lipid
Helps cells recognise eachother to form tissues
Acts as recognition sites for hormones
Help maintain membrane stability
What does cholesterol do
Reduces fluidity and leakage
What’s the fluid mosaic model
Fluid - the phospholipids move relative to one another giving it a flexible shape
Mosaic-the protein components vary in shape , size and pattern like a mosaic
What are the functions of membranes within the cell
Separates organelles from the cytoplasm so metabolic reactions can take place within them
Provides transport system
Isolates enzymes that might damage cells
Provides surfaces on which reactions can occur eg protein synthesis on the RER
What is osmosis
The movement of water from a high water potential to a low water potential across a partially permeable membrane
The water moves through aquaporins
What is water potential
The tendency of water to leave or enter cells
The number of free water molecules
Moves from high to low concentration
Describe the states cells can be in
Hypotonic -(pop) where the water potential is high
Hypertonic- low water potential
Isotonic- same eater potential
