Chapter 10: Assignment Questions COMPLETE Flashcards
An amphiphilic (or amphipathic) molecule has:
a polar end
a nonpolar end
both!
both!
Which end of a Phospholipid is Polar?
The Head
The Tail
The Head
All are Phospholipids except:
Phosphatidylethanolamine
Phosphatidylerine
Phosphatidylcholine
Sphingomyeilin
Sphingosine
Sphingosine
Which is the Polar end of Cholesterol?
The Hydroxyl Group (top)
Methyl Group (bottom)
Hydrocarbon Region (middle)
The Hydroxyl Group (top)
In water, which atoms carry a partial negative charge?
oxygen
hydrogen
oxygen
In water, which atoms carry a partial positive charge?
oxygen
hydrogen
hydrogen
Which side of a Phospholipid is water most likely to interact with?
The Fatty Acid Tail (hydrophobic)
The Polar Head (hydrophillic)
The Polar Head (hydrophillic)
How many Phospholipid Leaflets make up a Micelle?
1
3
2
1
Which is the least likely movement of a lipid in a lipid bilayer?
lateral diffusion
flip-flop
rotation
flip-flop
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
flippases/translocases
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
amphipathic lipid with saturated fatty acid tails
Which would give a lipid bilayer greater fluidity?
amphipathic lipid with unsaturated fatty acid tails
amphipathic lipid with saturated fatty acid tails
amphipathic lipid with unsaturated fatty acid tails
Which side of a Phosopholipid Bi-Layer is Carbohydrates found?
Extracellular Side
Cytosol
Towards the extracellular side
Integral membrane protein are:
Hydrophobic (only in membrane)
Hydrophilic (only outside membrane)
Amphipathic (both inside and outside membrane)
Amphipathic (both inside and outside membrane)
Peripheral Protein are:
Hydrophobic (only in membrane)
Hydrophilic (only outside membrane)
Amphipathic (both inside and outside membrane)
Hydrophilic (only outside membrane)
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)
the inside (lumen) of the ER (the non-cytosolic side)
Protein anchored in the membrane are physically able to be inserted in the lipid bilayer, because the anchors are:
hydrophobic
hydrophilic
hydrophobic
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
hydrophobic peptide or lipid anchor
The most common membrane-spanning structure is:
an alpha helix
a beta sheet
an alpha helix
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
insertion of hydrophobic helices across a lipid bilayer
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
hydrophobic
Which structure might only need a series of 10 amino acids to span a membrane?
alpha helix
beta-barrel
beta-barrel
What protein structure only has a membrane spanning region?
alpha helix
beta barrel
beta barrel
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
extracellular space
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
the reducing environment of the cytosol
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
SDS (sodium dodecyl sulfate)
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
its concentration increases linearly but then no longer continues to rise once the concentration hits the critical micelle concentration
The hydrophobic portions of detergents interact with:
hydrophobic amino acid side chains or lipids
hydrophilic portions of molecules
hydrophobic amino acid side chains or lipids
The portions of detergents that are most likely to interact with water are:
polar or charged groups
hydrophobic groups
polar or charged groups
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
interferes with protein secondary and non-covalent tertiary structure, thereby denaturing the proteins
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
proteins can diffuse around a leaflet of a lipid bilayer
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
FRAP
