Chapter 10: Assignment Questions COMPLETE

Question 1

An amphiphilic (or amphipathic) molecule has:

a polar end
a nonpolar end
both!

Answer 1

both!

Question 2

Which end of a Phospholipid is Polar?

The Head
The Tail

Answer 2

The Head

Question 3

All are Phospholipids except:

Phosphatidylethanolamine
Phosphatidylerine
Phosphatidylcholine
Sphingomyeilin
Sphingosine

Answer 3

Sphingosine

Question 4

Which is the Polar end of Cholesterol?

The Hydroxyl Group (top)
Methyl Group (bottom)
Hydrocarbon Region (middle)

Answer 4

The Hydroxyl Group (top)

Question 5

In water, which atoms carry a partial negative charge?

oxygen
hydrogen

Answer 5

oxygen

Question 6

In water, which atoms carry a partial positive charge?

oxygen
hydrogen

Answer 6

hydrogen

Question 7

Which side of a Phospholipid is water most likely to interact with?

The Fatty Acid Tail (hydrophobic)
The Polar Head (hydrophillic)

Answer 7

The Polar Head (hydrophillic)

Question 8

How many Phospholipid Leaflets make up a Micelle?

1
3
2

Answer 8

1

Question 9

Which is the least likely movement of a lipid in a lipid bilayer?

lateral diffusion
flip-flop
rotation

Answer 9

flip-flop

Question 10

Phospholipids are generally synthesized on only one leaflet of a lipid bilayer. Movement of one of these lipids to the other leaflet requires:

flippases/translocases
rotation
lateral diffusion

Answer 10

flippases/translocases

Question 11

Enrichment of which type of lipid in a domain of a lipid bilayer leads to a greater distance across the bilayer?

amphipathic lipid with unsaturated fatty acid tails
amphipathic lipid with saturated fatty acid tails

Answer 11

amphipathic lipid with saturated fatty acid tails

Question 12

Which would give a lipid bilayer greater fluidity?

amphipathic lipid with unsaturated fatty acid tails
amphipathic lipid with saturated fatty acid tails

Answer 12

amphipathic lipid with unsaturated fatty acid tails

Question 13

Which side of a Phosopholipid Bi-Layer is Carbohydrates found?

Extracellular Side
Cytosol

Answer 13

Towards the extracellular side

Question 14

Integral membrane protein are:

Hydrophobic (only in membrane)
Hydrophilic (only outside membrane)
Amphipathic (both inside and outside membrane)

Answer 14

Amphipathic (both inside and outside membrane)

Question 15

Peripheral Protein are:

Hydrophobic (only in membrane)
Hydrophilic (only outside membrane)
Amphipathic (both inside and outside membrane)

Answer 15

Hydrophilic (only outside membrane)

Question 16

A GPI-anchored protein is originally attached to its anchor in:

the cytosol
the extracellular space
the inside (lumen) of the ER (the non-cytosolic side)

Answer 16

the inside (lumen) of the ER (the non-cytosolic side)

Question 17

Protein anchored in the membrane are physically able to be inserted in the lipid bilayer, because the anchors are:

hydrophobic
hydrophilic

Answer 17

hydrophobic

Question 18

Sometimes, proteins such as small GTPases of the Rab protein family are able to anchor in a lipid bilayer in regulated fashion, because binding to GTP causes exposure of a ________ domain of the protein.

hydrophobic peptide or lipid anchor
hydrophilic

Answer 18

hydrophobic peptide or lipid anchor

Question 19

The most common membrane-spanning structure is:

an alpha helix
a beta sheet

Answer 19

an alpha helix

Question 20

Which occurs first?

insertion of hydrophobic helices across a lipid bilayer
association of one or more membrane-spanning helices, displacing interaction of some lipid tails with the helices

Answer 20

insertion of hydrophobic helices across a lipid bilayer

Question 21

Sometimes, amphipathic helices that have hydrophobic side chains facing one side and semi-hydrophilic helices facing the other are able to span the membrane. In this case, the side of the helix interacting with the lipid portion of the bilayer is most likely rich in ___________ side chains.

hydrophobic
hydrophilic

Answer 21

hydrophobic

Question 22

Which structure might only need a series of 10 amino acids to span a membrane?

alpha helix
beta-barrel

Answer 22

beta-barrel

Question 23

What protein structure only has a membrane spanning region?

alpha helix
beta barrel

Answer 23

beta barrel

Question 24

Proteins are often glycosylated in the lumen of the ER. If these proteins end up in the plasma membrane, the sugar groups face the:

extracellular space
the cytosol

Answer 24

extracellular space

Question 25

Disulfide bonds are least likely to occur on the surfaces of proteins exposed to: extracellular fluid the reducing environment of the cytosol the lumen of the ER

Answer 25

the reducing environment of the cytosol

Question 26

Which of these is the strongest detergent (in this case its polar end interacting more strongly with water and hydrophilic regions of proteins than is the case for the other two)? SDS (sodium dodecyl sulfate) Triton X-100 beta-octylglucoside

Answer 26

SDS (sodium dodecyl sulfate)

Question 27

As detergent is added to a solution: its concentration increases directly with the amount of detergent added all the way through the range of solubility its concentration increases linearly but then no longer continues to rise once the concentration hits the critical micelle concentration

Answer 27

its concentration increases linearly but then no longer continues to rise once the concentration hits the critical micelle concentration

Question 28

The hydrophobic portions of detergents interact with: hydrophobic amino acid side chains or lipids hydrophilic portions of molecules

Answer 28

hydrophobic amino acid side chains or lipids

Question 29

The portions of detergents that are most likely to interact with water are: polar or charged groups hydrophobic groups

Answer 29

polar or charged groups

Question 30

A strong ionic detergent like SDS: gently surrounds proteins and preserves their native conformations interferes with protein secondary and non-covalent tertiary structure, thereby denaturing the proteins

Answer 30

interferes with protein secondary and non-covalent tertiary structure, thereby denaturing the proteins

Question 31

This elegant experiment that fused a mouse cell with a human cell (and stained to show the location of the mouse or human proteins on the cell surface) shows that: proteins can diffuse around a leaflet of a lipid bilayer proteins are always anchored to one spot in a lipid bilayer

Answer 31

proteins can diffuse around a leaflet of a lipid bilayer

Question 32

Another way to assess movement of a membrane component into an area of membrane that is bleached of fluorescence of fluorescently-tagged molecules is: FRET FRAP

Answer 32

FRAP