Plasma Membrane Flashcards
Describe the saturated property of phospholipids in the bilayer
with straight, saturated fatty acids tails align more closely and so reduce fluidity,
Describe the unsaturated property of phospholipids in the bilayer
prevented form moving too closely together by the kink formed by the double carbon bond and so increase fluidity.
What does cholesterol molecules do when temperature is high ?
it holds the phospholipids together, preventing the membrane from becoming too fluid.
What does cholesterol molecules do when temperature is low ?
Prevents the phospholipids from packing too closely , retaining fluidity.
Why is fluidity important?
vital for providing structural support and permitting movement of the cell
Why is membrane fluidity further important? I
It allows the insertion of membrane proteins within the lipid bilayer.
What can membrane proteins be classified as?
Peripheral
Intergral
Where are peripheral proteins on the membrane?
sit on the inner or outer surface of plasma membrane attahced to polar heads of phospholipds
e.g glycoproteins such as glycocalyx- functions in cell recognition and adhesion
Where are integral proteins on the membrane?
span the whole plasma membrane and are firmly anchored between the fatty acid tails.
Why are oxygen and carbon dioxide is able to transport across the plasma membrane unaided?
They have no charge and small.
What integral proteins allow the passage of ions and large molecules through the plasma membrane?
sodium and potassium ions pass-through
-selective ion channel proteins- allows the flow of specific ions from one side to another in the plasma membrane- selective to the ion channel
- carrier proteins - glucose carrier proteins - transport specific substances across the plasma membrane
-receptor proteins- bind to specific molecules and lead to an alteration in cellular function
which can be passive or active (depending on the energy)
Why are molecules such as potassium or sodium unable to pass across the membrane?
As they are too large and have a charge
What is the fluid mosaic model?
Mosaic - as it contains many embedded membrane proteins disperersed in the mosaic arrangement.
What is the fludity of the phospholipid based on?
amount of cholesterol
composition of lipid in bilayer
What makes up the glycocalyx and what function does it serve?
carbohydrates
-which are used in cell recognition and adhesion
