Lecture 21-28

Question 1

Fatty acids

Answer 1

Carboxylic acids with long hydrocarbon chains. Number of carbons and degree of unsaturation determine properties. More energy per C than carbohydrates

Question 2

Saturated fatty acids

Answer 2

No double bonds. Solids at room temperature. Higher melting point as number of carbons increases

Question 3

Unsaturated fatty acids

Answer 3

Double bonds present. Liquids at room temperature. Melting point increases as number of carbons increases, but drastically decreases as number of double bonds increases

Question 4

Triacylglycerols (TAG)

Answer 4

Three fatty acids in ester linkage with one glycerol. Nonpolar, hydrophobic, neutral molecule. Fat storage for energy production, heat production, and thermal insulation

Question 5

Glycerophospholipids

Answer 5

Two fatty acids with phosphate head group. Variability at phosphate alcohol for different head group additions. Tails and head linked by ester linkages to glycerol

Question 6

Sphingolipids

Answer 6

Sphingosine backbone (amino alcohol) with amide linked fatty acid. Polar head groups linked with glycosidic or phosphodiester bonds

Question 7

Glycocalyx

Answer 7

Carbohydrate layer on biological membranes. Helps with tissue/organ specificity; cell recognition, adhesion, and migration; blood clotting; immune responses; wound healing; and nerve impulse transmission

Question 8

Other structural lipids

Answer 8

Ether-linked lipids and waxes

Question 9

Integral proteins

Answer 9

Monotopic (on one side) or polytopic (span the membrane). Embedded due to hydrophobic region of the protein. Removed with hydrophobic agent

Question 10

Peripheral proteins

Answer 10

Attach via electrostatic or H-bonding. Removed with mild detergents or by interfering with electrostatic/hydrogen bonds

Question 11

Amphitropic proteins

Answer 11

Reversible attachment to membrane lipids. Can be modified by covalent/noncovalent modifications (lipidation, phosphorylation, ligand binding)

Question 12

Glycophorin

Answer 12

Type I integral membrane protein. Amino terminus on exterior and carboxyl terminus on interior. One hydrophobic region

Question 13

Bacteriorhodopsin

Answer 13

Type III integral membrane protein. Proton pump with trimer structure. Each monomer has seven helices that cross the membrane. Contains retinal that absorbs light and changes structure

Question 14

Liquid ordered (Lo) state

Answer 14

Membrane below melting temperature. More solid with less lipid movement. Higher concentration of unsaturated lipids at lower Tm

Question 15

Liquid disordered (Ld) state

Answer 15

Membrane above melting temperature. More fluid with more lipid movement. Higher concentration of saturated lipids at higher Tm

Question 16

Flippase

Answer 16

Catalyzes movement of lipids to inner leaflet. Requires ATP

Question 17

Floppase

Answer 17

Catalyzes movement of lipids to outer leaflet. Requires ATP

Question 18

Scramblase

Answer 18

Moves lipids in both directions towards equilibrium

Question 19

Lipid raft

Answer 19

Microdomains enriched with cholesterol, sphingolipids, and GPI-anchored proteins on outer leaflet. Thicker and shows more Lo state

Question 20

Specificity

Answer 20

Complementary binding between receptor and specific ligand

Question 21

Amplification

Answer 21

Enzymes activate other enzymes and increase the number of affected molecules

Question 22

Modularity

Answer 22

Proteins form diverse signaling complexes from interchangeable parts

Question 23

Desensitization/Adaptation

Answer 23

Receptor activation triggers feedback mechanism that shuts off receptor

Question 24

Integration

Answer 24

Converts multiple signals into one overall signal that influences a response

Question 25

Localized response

Answer 25

Produces local and brief responses because the messenger degradation protein is located nearby