Human Phys 1.1 Flashcards
What is the common structure of all cell membranes?
They are composed as phospholipids
What type of structures are cell membranes?
Dynamic and fluid structures
What can membrane constituents do?
Move about the plane of the membrane
What percentage of proteins encoded in an animal cells genome are membrane proteins?
30%
What is the most predominant type of phospholipids?
Phosphoglycerides
What do phosphoglycerides contain?
Glycerol backbone
2 hydrocarbon tails
Phosphate group attached to glycerol backbone
What is the tail on a phosphoglyceride?
Hydrophobic
What is the head on a phosphoglyceride?
Hydrophilic
Where does the cis double bond (kink) occur?
In one of the hydrocarbon tails
What does the cis double bond (kink) cause?
Width of lipid bilayer to be shorter
More space between lipid bilayer
What does the cis double bond (kink) increase?
Increases membrane fluidity (important for proper physiological function)
What can phospholipids do?
Spontaneously form bilayers (do it on their own with no help)
What do phospholipid bilayers do because of their amphiphilic nature?
Bury their hydrophobic tails in the interior and expose their hydrophilic heads to water
What does a cone shaped lipid molecule form?
Micelle
What does a cylinder shape lipid molecule form?
Lipid bilayer
What is the importance of lipid molecules being able to spontaneously form?
Important for self healing capability
How does the spontaneous closure of a phospholipid bilayer work?
Hydrophobic edges are exposed to water (energetically unfavorable)
They fold up into a sphere to prevent water from touching hydrophobic edges (energetically favorable)
What can membrane proteins do?
Move freely around the bilayer
What are the different mechanisms that cells can tether membrane proteins?
Self assemble
Tethered to macromolecules on the outside
Tethered to macromolecules on the inside
Tethered to macromolecules in the surface of another cell
What restricts proteins to specific domains?
Tight junction
Why is it important that the tight junction restricts proteins to specific domains?
So functions carry out correctly (everything moves the right direction)
