Membrane Flashcards
The point of Membranes?
are structures that separate the contents within a cell from the environment.
Also separate the different areas within cells (organelles)
compartmentalisation.
Membrane structure?
known as a plasma membrane.
formed of a phospholipid bilayer, hydrophilic phosphate head, hydrophobic tail.
fluid- mosaic model?
proteins occupy various positions in the membrane.
types of proteins in the membrane?
Intrinsic and extrinsic.
name the intrinsic proteins?
channel proteins
carrier proteins
Glyco proteins
glycolipids
extrinsic proteins? name them?
present in one side of the bilayer, normally have hydrophilic r groups on their outer surface and interact with that with the polar heads of the phospholipids or intrinsic proteins.
cholesterol
what do channel proteins do?
provide a hydrophilic channel that allows the passive movement of polar molecules and ions down a concentration gradient through Membranes.
held in position by interaction between the hydrophobic core of the membrane , hydrophobic r groups on the outside of proteins
carrier proteins?
have an important role in both passive and active transport into cells .
often involves the shape of the protein changing
Glyco proteins?
embedded Into the cell surface membrane with attached carbohydrates chains of varying lengths+ shapes
when a chemical binds to a receptor, causes a response from the cell. causing a direct response or set off a cascade of events, known as cell communication or signalling
glycolipids ?
similar to glycolipids, lipids with attached carbohydrates chains. these molecules are cell marker’s or antigens and can be recognised by the cell of the immune system of organism of non cell
cholesterol?
lipid with hydrophilic end and a hydrophobic end , regulates the fluidity of Membranes.
positioned between phospholipids in a membrane bilayer.hydrophillic end interacting with the heads and hydrophobic end Interacting with the tails pulling them together.
adds stability with becoming too rigid
factors affecting Membrane structure? temperature?
temperature - when temperature is increased the phospholipids have more kinetic energy and move more, makes the membrane more fluid and loose structure. cell will eventually break down.
loss of structure Increases permeability.
proteins are denatured at 50°c
factors affecting Membrane structure? solvent?
organic solvents with dissolve Membranes and disrupting cells creating gaps increasing permeability due to them not being as polar as water so can enter the cell
