Membrane Structure

Question 1

Fluid mosaic

Answer 1

Allow proteins to move laterally. Bc of non-covalent bonds such as van deer wale and hydrophobic effects.
Selectively permeable barriers

Question 2

Micelles

Answer 2

Form if the cross sectional area of the polar group is greater than that of the acyl side chain

Question 3

Bilayer

Answer 3

Forms if non polar and polar regions have similar areas

Question 4

Liposome

Answer 4

Hollow vesicles where unstable bilayer folds back on itself

-will form when dispersed in aqueous medium

Question 5

The most abundant lipid in cell membranes

Answer 5

Phospholipid

Question 6

Phospholipids

Answer 6

2 hydrophobic fatty acid chains linked to phosphate-containing polar head
2 chains can differ in length and saturation.
Presence of double bond causes a kink

Question 7

Glycerol phospholipids

Answer 7

Fatty acids attached to each of the first 2 carbons of glycerol via ester bond and a phosphate group attached to 3rd carbon
-named based on alcohol group attached to the phosphate in polar head

Question 8

Sphingolipid

Answer 8

Phospholipid. Contain sphingosine(amine alcohol w long hydrocarbon chain)
-ex is sphingomyelin (contains phosphate polar head)

Question 9

Glycolipids

Answer 9

Lipids containing a carbohydrate moiety

Question 10

Cholesterol

Answer 10

Amphipathic sterol.
Too hydrophobic to form bilayer on their own
-ensures fluidity by preventing phospholipids from packing too closely.
-maintain rigidity and decrease permeability

Question 11

Inner leaf

Answer 11

Phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol (signaling)

Question 12

Outer leaf

Answer 12

Phosphatidylcholine, sphingomyelin, glycolipids

Question 13

Lower temperatures

Answer 13

Gel state, fatty ache chains packed closer, fluidity decreased

Question 14

Temperature increases

Answer 14

Fluid state. Energy to overcome forces, thickness of bilayer decreases, fluidity increases

Question 15

Lipid raft

Answer 15

Cholesterol, sphingolipids, phospholipids, and saturated tails are closely packed and less fluid, create these
Play role in signal transduction

Question 16

Flippase

Answer 16

Transfer lipids to other leaf. Outside to inside

ATP dependent. Occurs slowly (24hr)

Question 17

Floppases

Answer 17

ATP dependent, from cytoskeleton to extracellular. Inside to outside

Question 18

Scramblases

Answer 18

In either direction along concentration gradient.

No ATP required, activity increases when intracellular Ca increases

Question 19

Integral proteins

Answer 19

Inserted in membrane. Span bilayer. Covalently attached to leaflet. Only released by disrupting bilayer with detergents or organic solvents

Question 20

Peripheral proteins

Answer 20

Associated w integral and membrane lipids by non covalent bonds. Can be removed without disrupting bilayer by high salt or extreme pH

Question 21

Porins

Answer 21

Transmembrane proteins which multiple B strands fold into barrel conformation, inside is hydrophilic and allows small solutes and ions to cross the membrane