the plasma membrane is also referred to as what?
in reference to ions and organic molecules the plasmalemma is referred to as being what?
proteins that are permanently associated with the membrane
integral membrane proteins
proteins that are transiently associated with the membrane
peripheral membrane proteins
what makes up 50% of the plasma membrane volume
by weight, cholesterol accounts for what percentage of the lipid portion of the cell membrane
cholesterol and protein are in a _____ ratio
1 to 1
cholesterol and proteins inhabit which layers of the membrane
BOTH the inner and outer leaflets
the glycolipids account for ___ % of the membrane and are found on what layer of the membrane
5% and are found only on the outer leaflet
what are the three families of lipids found in the membrane
phospholipids, glycolipids and cholesterol
what forms the backbone of most phospholipids?
the phospholipid is composed of what 5 parts
1) hydrophillic head 2) glycerol unit 3) phosphate group and two nonpolar hydrocarbon tails (4&5)
what does amphipathic mean?
possesses both hydrophobic and hydrophilic regions
what is it called when a single phospholipid changes positions with another phospholipid on the same leaflet
what is it called when a phospholipid changed positions with another phospholipid on the opposite leaflet?
flip flopping and it rarely happens
what is the backbone of a glycolipid called?
what are the important roles of the glycolipid?
cell recognition and as the antigenic determinant for A/B/O blood type
what are two types of glycolipids?
cerebrosides found in muscle and nerve cell membranes and gangliosides found in the nerve cell membranes
what are the components of a cholesterol
polar head, planar steroid ring structure and a nonpolar hydrocarbon tail
in general the cholesterol makes the membrane
more rigid and less permeable
what are the four different ways in which proteins are associated with the membrane
integral (transmembrane), monolayer-assocaited, lipid-linked and protein attached
integral proteins are found as both ___ and ___?
transmembrane and monolayer associated
in a lipid anchored proteins, how is the protein attached to the lipid molecule?
they are covalently bound
how are the peripheral proteins associated with the plasma membrane
they are associated through attachment to an integral membrane protein
what are the four functional classes of transmembrane proteins
transporters, anchors, receptors and enzymes
lipid rafts are also called what
in the lipid raft there are high concentrations of what?
high concentrations of sphingolipids and cholesterol
what is the cellular function of the lipid raft in reference to the signaling molecules
the lipid raft is the organizing center for the asembly of the signaling molecules
what are the other cellular functions of the lipid raft?
they influence membrane fluidity and membrane protein trafficking and they regulate neurotransmission and receptor trafficking (whatever that means)
what are the two types of lipid rafts
planar and caveolae
the caveolae orientation of the lipid raft plays a role in what?
plays a role in clathrin-independent endocytosis
the caveolae lipid raft endocytosis is ______independent
what are the four functions of the plasma membrane
communication, intracellular connection, physical barrier and selective permeability
endocytosis utilizes the membrane-bound compartments knows as
endosomes formed from the invagination of the plasma membrane
the endosome is transferred to what organelle for degredation?
exocytosis delivers proteins and lipids to various sites within a CELL inside membrane enclosed compartments known as what?
transport vessicles, once it reaches the membrane it fuses with the membrane and releases the contents
transport vessicles originate from what organelle?
after the ER the transport vesicles are sent where?
the golgi apparatus and then to the final cargo delivery
what are the tree types of endocytosis
phagocytosis, pinocytosis and receptor-mediated endocytosis
the coated pits associated with receptor medicated endocytosis are compsed of what
small proteins called CLATHRIN intracellular
cholesterol uptake is what type of endocytosis
its an example of receptor mediated endocytosis
cholesterol forms a compelx with what in te bloodstream?
what happens to the LDL receptor after the LDL has been taken up by the cell
the LDL receptor is recycled
what are the two types of exocytic pathways?
constitutive secretions and regulated secretions
constitutive secretion does what
supplies newly made lipids and proteins to the plasma membrane
regulated secretion is what?
THIS IS ONLY DONE IN CELLS SPECIALIZED IN SECRETIONS.