Phospholipids and Proteins Flashcards
(28 cards)
What are phospholipids?
A type of hydrophobic and non-polar lipid, made of two fatty acid chain ‘tails’ attached to a hydrophilic and polar phosphate group ‘head’.
What is the shape that the phospholipids form due to?
Their polar nature and the way they interact with water.
Which two things will the phospholipids form?
A bilayer or a micelle.
What does the phospholipids act as in a membrane?
A barrier to most substances, which help control what enters/exits the cell.
What type of molecule will diffuse faster and easier across a membrane?
The smaller and less polar
Examples of molecules which will diffuse rapidly.
Oxygen and Carbon Dioxide. (non polar and small)
Examples of molecules which will diffuse slowly.
Water and Urea. ( polar and small)
Examples of molecules which are unlikely to diffuse.
Charged particles (ions) even if they are small.
What are the two types of proteins?
Intrinsic and Extrinsic.
Where are the intrinsic proteins found?
Span the whole width of the membrane.
Where are the extrinsic proteins found?
Are confined to the inner or outer surface of the membrane.
How much space do proteins in membranes make up? And how much?
Make up 45% by mass of cell membrane but can vary from 25% to 75% depending on cell type.
Many Intrinsic Proteins are…
Carrier Molecules or Channels.
What is the function of the Intrinsic Proteins?
Help transport substances such as ions that cannot diffuse across the membrane but are still vital to a cells functioning.
What are other examples of Intrinsic Proteins?
Receptors for Hormones and Neurotransmitters.Enzymes for Catalysing Reactions.
What 2 sides can the extrinsic proteins be on?
Extracellular or Cytosolic
On the Extracellular side what function do the extrinsic proteins have?
Act as receptors for hormones or neurotransmitters.Involved are cell recognition.
What type of proteins are most common as extrinsic proteins?
Glycoproteins.
On the Cytosolic side what function do the extrinsic proteins have?
Involved in cell signalling or chemical reaction.
What can happen to the extrinsic proteins on the cytosolic side?
They can disassociate from the membrane and move into the cytoplasm.
What are Glycolipids?
Lipids with attached carbohydrate chains.
What are Glycolipids also known as?
Cell markers or antigens.
In which two ways can the glycolipids be recognised by the cells of the immune system?
As self of the organism.Non-self of cells belonging to another organism.
What are Glycoproteins?
Proteins embedded into the cell surface membrane with attached carbohydrate chains of various lengths and shapes.
