7 Membrane Structure and Function Flashcards
What is the key feature of the plasma membrane?
It is selectively permeable.
What is the key feature of the plasma membrane?
It is selectively permeable.
What are the physical properties of a phospholipid
It has a hydrophilic head and hydrophobic tail (it is amphipathic)
What does ‘amphipathic’ mean?
It has a hydrophilic and a hydrophobic region?
A phospholipid has both a hydrophilic and hydrophobic section. What does this mean it is?
Amphipathic.
What model describes how a phospholipid membrane is arranged?
The phospholipids and proteins are arranged according to the ‘fluid mosaic model’
How does the fluid mosaic model describe the phospholipid membrane?
It is bilayer of phospholipids interspersed with proteins. This layer is fluid i.e. dynamic.
Where are the proteins of the phospholipid membrane located?
These proteins are also amphipathic so they go all the way through the membrane.
How is the lipid bilayer held together?
By the hydrophobic tails of the phospholipids as they exert an attractive force ad thus prevent the layers form separating.
In what was is a phospholipid membrane dynamic?
It has fluidity in which adjacent phospholipids with places as do the occasional opposite phospholipids.
What can cause a decrease in membrane fluidity?
A decreased temperature.
How can the components of the phospholipid membrane affect its fluidity?
If the phospholipids have unsaturated hydrocarbon tails they will be kinked which prevents packing and thus makes it more fluid.
Alternately cholesterol can be added to adjust fluidity.
How does integrating cholesterol into a membrane affect membrane fluidity?
At moderate temperatures it reduces fluidity by reducing phospholipid movement.
However at low temperatures it prevents solidification by preventing packing.
Thus it acts as a buffer to cause intermediate fluidity.
Why is membrane fluidity important?
It allows the enzymes and other membrane proteins to more easily collide with their substrates etc.
What are the basic functions of transmembrane proteins?
Transport, Enzymes, Signal Transduction, Cell-Cell recognition, Joining adjacent cells; and attaching to the cytoskeleton and ECM.
What are the basic functions of transmembrane proteins?
Transport, Enzymes, Signal Transduction, Cell-Cell recognition, Joining adjacent cells; and attaching to the cytoskeleton and ECM
What are the physical properties of a phospholipid
It has a hydrophilic head and hydrophobic tail (it is amphipathic)
What does ‘amphipathic’ mean?
It has a hydrophilic and a hydrophobic region?
A phospholipid has both a hydrophilic and hydrophobic section. What does this mean it is?
Amphipathic.
What model describes how a phospholipid membrane is arranged?
The phospholipids and proteins are arranged according to the ‘fluid mosaic model’
How does the fluid mosaic model describe the phospholipid membrane?
It is bilayer of phospholipids interspersed with proteins. This layer is fluid i.e. dynamic.
Where are the proteins of the phospholipid membrane located?
These proteins are also amphipathic so they go all the way through the membrane.
In what way and where a membrane proteins and lipids modified?
The ER adds carbohydrates to some transmembrane proteins to make them glycoproteins.
However only in Golgi are carbohydrates added to lipids to form glycolipids. In the Golgi the carbohydrates of some glycoproteins are also modified.
In what was is a phospholipid membrane dynamic?
It has fluidity in which adjacent phospholipids with places as do the occasional opposite phospholipids.