Deck 8: Lipids and Membranes

Question 1

Which of the following is considered an omega-3 fatty acid?

A) 9,12-Octadecadienoic acid
B) 9,12,15-Octadecatrienoic acid
C) 6,9,12-Octadecatrienoic acid
D) 8,11,14-Eicosatrienoic acid
E) 5,8,11,14-Eicosatetraenoic acid

Answer 1

9,12,15-Octadecatrienoic acid

Question 2

Which of the following alcohols is esterified to the phosphate group of glycerophospholipids?

A) choline
B) ethanolamine
C) glycerol
D) serine
E) all of the above

Answer 2

all of the above

Question 3

Which of the following explains why free fatty acids do not form bilayers?

A) the width of the polar head is greater than the nonpolar tail
B) the width of the polar head is less than the nonpolar tail
C) the width of the polar head is equal to the nonpolar tail
D) the width of the nonpolar head is greater than the polar tail
E) the width of the nonpolar head is less than the polar tail

Answer 3

the width of the polar head is greater than the nonpolar tail

Question 4

As temperatures grow colder with the onset of winter, animals will adapt by changing the fatty acid composition of cell membranes. What characteristics of fatty acids will be seen?

A) longer chains with greater unsaturation
B) longer chains with greater saturation
C) shorter chains with greater unsaturation
D) shorter chains with greater saturation
E) chain length and saturation do not change in a cell membrane

Question 5

If a transmembrane domain of protein contains $\beta$ -sheet structure, the overall structure of the transmembrane portion is likely a ____________.

A) $\beta$ -barrel
B) $\beta$ -tube
C) $\beta$ -turn
D) $\beta$ -helix
E) none of the above

Question 6

Which fatty acid is commonly attached to proteins to allow membrane localization?

A) eicosapentaenoic acid (EPA)
B) arachidonic acid
C) linoleic acid
D) myristic acid
E) farnesylic acid

Question 7

If polar amino acids are found in a membrane spanning $\alpha$ -helical region, they are most likely _____.

A) mutations
B) modified with nonpolar groups by prenylation, methylation and/or acylation
C) hydrogen-bonded to other polar amino acids to prevent interaction with the membrane lipids
D) hydrogen-bonded with hydroxyl groups of the membrane fatty acids
E) none of the above

Question 8

Which of the following is a characteristic of integral membrane proteins?

A) most of their movement is by lateral diffusion
B) transverse diffusion occurs often but rather slowly
C) interactions between proteins makes the membrane highly rigid
D) all have carbohydrates attached to the extracellular domain
E) none of the above

Question 9

The carbohydrate portion of a membrane spanning glycoprotein is found _____.

A) spanning the membrane
B) on both the cytoplasmic and extracellular sides of the membrane
C) only on the cytoplasmic side of the membrane
D) only on the extracellular side of the membrane
E) carbohydrates are not found on membrane spanning glycoproteins

Question 10

Which of the following aspects of membrane protein movement is explained by the fluid mosaic model?

A) proteins that are immobile are often esterified to cholesterol via an Asp residue
B) proteins that are mobile only in a small area are sequestered by proteins attached to the cytoskeleton
C) proteins that freely diffuse through the membrane often undergo flip-flopping
D) proteins confined to a lipid raft are linked to phosphatidylserine via and amide bond
E) none of the above

Question 11

___ and ___ have the appropriate geometry to form lipid bilayers while ___ tends to form micelles.

Question 12

For a saturated fatty acid, melting point _____ with increasing chain length due to a greater number of _____ interactions.

Question 13

In a mixed bilayer, longer acyl chains tend to be ___ than shorter acyl chains and unsaturated acyl chains are ___ than saturated chains.

Question 14

In a mixed bilayer, cholesterol restricts the movement of nearby acyl chains, thus preventing the membrane from becoming too ___. Cholesterol inserts between membrane lipids, preventing close packing, thus preventing the membrane from becoming too ___.

Question 15

Transverse diffusion occurs ___ lateral diffusion occurs ___.

Question 16

A membrane protein in a lipid raft will ___ a membrane protein attached to the cytoskeleton will ___.

Question 17

Considering the characteristics of common fatty acids found in animals described in the text, which of the structures shown below would you consider the rarest fatty acid if found in animals?

A)
B)

C)

D)

E) All structures would be equally rare.

Question 18

Which of the structures below is an example of an $\omega$ -3 polyunsaturated fatty acid?

A)
B)
C)
D)
E) none of the above

Question 19

Which of the following structures correctly represents a glycerophospholipid?

A)

B)

C)

D)


E) none of the above