Beta- membrane structure and trans

Question 1

describe the four classes of membrane lipids

Answer 1

1. Phosphoglyrides- derived from 3 carbon glycerol backbone. And 2 fatty acid chains attached to the backbone.
2. Sphingolipids- derived from a sphingosine backbone.
3. glycolipids- sphingosine backbone with a carbohydrate attached. 4. sterols- primarily cholesterol

Question 2

what about plasma membranes gives them the ability to assemble into a bilayer?

Answer 2

their amphipathic nature. The polar head and the non-polar fatty acid tail.

Question 3

describe the basic structure of a phosphoglyrides

Answer 3

1. two fatty acid chains attached to two or three carbons backbone.
2. one chain usually in non saturated and has a kink in it.
3. the head group determins what the specific phospholipid type will be.

Question 4

what is the point of the kink

Answer 4

to keep the plasma membrane from solidifying. keeps it fluid

Question 5

what else helps with keeping the plasma membrane fluid?

Answer 5

the fact that the lipid- protein interactions are non covalent. it allows the proteins and lipids to move around the PM

Question 6

what is the difference between a phospholipid and sphingolipid?

Answer 6

sphingolipid has an amine group

Question 7

what is the function of a sterol in the PM

Answer 7

cholesterol is made of a stiff sterol ring. it stiffens the regions of membrane in its vicinity.

Question 8

what is the difference between a glyocolipid and a phospholipid?

Answer 8

sphingosine + phosphate = phospholipid

sphingosine + sugar =glycolipid

Question 9

why is there no cholesterol in bacterial?

Answer 9

bacterial have no plasma membrane they have a cell wall

Question 10

what is the trend of different lipids in either PM leaflet?

Answer 10

phosphotydalserine and phosphotydalethalamine are found on the inner leaflet.

glycolipids, phosphotidal choline and sphingolipids are found more on the inner leaflet

Question 11

what is a lipid raft and what does it do for a PM?

Answer 11

lipid rafts are an area of dispropotional distribution of certain specific lipids. it sequesters certain types of proteins and only those proteins are allowed near the raft

Question 12

what is the property that a protein must posses to be an integral protein?

Answer 12

it must have an internal hydrophobic patch that can span the PM.

Question 13

how does a periferal membrane protein remain associated to the PM?

Answer 13

via charges (electrostatic reactions).

peripheral proteins can also attach to specific lipids in the bilayer.

Question 14

spectrin doesnt fit into the category of integral or periferal proteins. Why is it still important?

Answer 14

spectrin is there to anchor the internal cytoskeleton of proteins in place.

Question 15

what is the difference between a pump, a channel and a carrier

Answer 15

1. pumps are slow and selective but require energy (against concentration gradient)
2. carrier proteins are also slow but require NO energy (down concentration gradient)
3. channels are fast transporters but specific that require NO energy But can move a lot of product in a short amount of time

Question 16

which of the three transport systems are passive vs. active?

Answer 16

carrier proteins and channel mediated transport is passive. ion pumps are active and use ATP

Question 17

what is a uniport compared to a symport?

Answer 17

uniport is carrier protein that transports one molecule down its concentration gradient.

Symport on the other hand, uses the concentration of one molecule to aid the transport of a second molecule against its concentration gradient by moving both of them at the same time.

Question 18

how is the transport of glucose make use of a uniporter vs. symporter and when is each use over the other?

Answer 18

The uniporter is used to transport glucose down its concentration gradient and the symporter is used to transport glucose against its concentration gradient without using energy

Question 19

how is the ABC transporter different from the P-type transporter?

Answer 19

the P-type transporter is a ion pump that pumps ions using one ATP. the ABC transporter doesnt pump ions but rather small molecules. it requires the binding of two ATP molecules

Question 20

what is the clinical relevance of type P1 type transporter?

Answer 20

P1 type transporters are how your body returns calcium into the sarcosplasmic reticulum of the muscles after it has been released for muscle contraction.

Question 21

what binds first always in the ABC transporter?

Answer 21

in both import and export, the ABC transporter (whichever side the molecule is coming from) will bind first. then the two ATP molecules will bind causing a conformational change which opens the other end of the ABC protein and the molecule is released.

Question 22

what role does ABC play in multiple drug resistance?

Answer 22

in many cancer patients, as a consequence of treatment, multiple ABC transporters appear in the membrane. This thus increases the rate at which the drug is cleared from the cell thus reducing the effectiveness of the drug.