Deck 9: Biological Membranes

Question 1

Fatty acids consist of

A) A hydrocarbon chain and an alcohol group on one end
B) A hydrocarbon chain and an ester bond at the far end
C) A hydrocarbon chain and an ether bond at the far end
D) A hydrocarbon chain and an carboxylic acid group at the far end
E) A hydrocarbon chain and an SH group at the far end

Answer 1

D

Question 2

M otio n o f lipid s in a b iolo gic al m em br an e is

A) Slow in all directions
B) Slow across the membrane, but fast in the plane of the membrane
C) Rapid in all directions
D) Fast across the mem brane, but slow in the plane of the mem brane
E) Re stricte d ex cep t in lipid rafts

Answer 2

B

Question 3

Cardiolipin consists of

A) Sphingomyelin with attached carbohydrate molecules
B) Two sphingosine molecules linked by a glycerol
C) Tw o ph osp hatidyl ch oline m olec ules linked by a ph osp hate
D) Two phosphatidic acid molecules linked by a glycerol
E) Tw o ce ram ide m olec ules linked by a ph osp hate

Answer 3

D

Question 4

The first p art of a sec reted prote in to be trans lated is called its

A) Initiation sequence
B) O rig in
C) Signal sequence
D) Target sequence
E) Recognition sequence

Question 5

Molecules having a lipophilic part spatially separated from a hydrophilic part are called

A) Am bivalent
B) Am ph ipat hic
C) Zw itter ion ic
D) Integral
E) Peripheral

Question 6

Surface tension is best described as

A) The surface energy per unit area
B) The su rfac e en ergy p er un it length
C) The force or tension per unit area
D) The force per unit volume
E) The surface energy per unit volume

Question 7

In phospholipids, the phosphate is generally bonded between

A) Fatty acid and glycerol
B) Glycerol and hydrophilic group such as choline
C) Fatty acid and serine
D) Glycerol and glucose
E) Fatty acids and glucose

Question 8

Secreted proteins cross the mem brane of the ER

A) By diffusion
B) By active transport
C) Through a channel provided by a translocon
D) By o sm os is
E) Through a channel made by the SRP

Question 9

The thickness of biological membranes is about

A) 10 µm
B) 1 µm
C) 100 nm
D) 10 nm
E) 1 nm

Question 10

The m ajor h ydrop hilic part o f a ph osp hatidylino sitol is its

A) Glycerol
B) Ph osp hate
C) C is F atty a cid
D) Inositol
E) T ra ns fat ty ac id

Question 11

Am phipathic molecules

A) Prefer organic solvents such as chloroform or CCl4 as a solvent
B) Prefer water as a solvent
C) Have spatially separated lipophilic and hydrophilic regions
D) Have spatially separated positive and negative charges on their surface
E) Are solub le in ne ither w ater n or lipid so lvents

Question 12

The surface tension of pure water is 72 dyne cm-1. Addition of surfactant lowers the surface tension to 60 dyne cm -1. W ith th e s ur fa cta nt, t he su rfa ce pre ss ur e is

A) 12 dyne cm -1
B) 132 dyne cm -1
C) 0.166 dyne cm -2
D) 0.20 dyne cm -2
E) Cannot be determined from the information given

Question 13

The signal recognition peptide

A) Binds to the signal sequence and to the SRP receptor
B) Binds to the signal sequence and to the translocon
C) Binds to the SRP and to the translocon
D) Binds to the signal sequence inside the ER lumen
E) Helps fold up proteins inside the ER

Question 14

The m ajor h ydrop hob ic par t of a p hos pho lipid is its

A) Glycerol
B) Ph osp hate
C) Fa tty ac id
D) Inositol
E) Choline

Question 15

Which of the following is NOT a polar group used in phospholipids?

A) Serine
B) Inositol
C) Choline
D) Ethanolamine
E) Alanine

Question 16

The orig in o f th e s ur fa ce ten sio n o f w ate r at the wa ter -a ir int er fa ce is

A) Air pressure pushing on the water surface
B) Water molecules attracting other water molecules more than the air attracts them
C) W ater in the bulk phase being at a higher energy than water at the surface
D) Attractive forces of air molecules that tend to exclude the water
E) The hydrophilic nature of air molecules

Question 17

Integral proteins

A) Have irreducible functions
B) Are loosely bound to mem branes
C) Are constituents of ribosomes
D) Are tightly bound to mem branes
E) Require high salt for removal from mem branes

Question 18

The m ain ing re die nt o f th e lip id b ilaye r in m os t bio log ica l m em br an es is

A) Phospholipids
B) Cholesterol
C) Free fatty acids
D) Triglycerides
E) C ar dio lipin

Question 19

Which of the following is not a constituent of a phospholipid?

A) Fa tty ac id
B) Glycerol
C) Ph osp hate
D) Choline
E) Cholesterol

Question 20

Kinks are formed in hydrocarbon chains that

A) Bind proline
B) H av e a tra ns do ub le b on d in the hyd ro ca rb on ch ain
C) Ha ve a cis do ub le bo nd in th e hy dro carb on cha in
D) Are saturated
E) Are esterified to cholesterol