10 Questions
Which of these macromolecules is NOT commonly found in the plasma membrane?
nucleic acids
Plasma membrane proteins that move ions in and out of cells using active transport are called
transporters.
If a phospholipid is located in the outer layer of the bilayer in a vesicle, where will it end up when the vesicle fuses with the plasma membrane?
the cytosolic face of the bilayer
The fluidity of a membrane is increased by
Unsaturated fatty acids
A cell membrane made up primarily of lipids with which characteristics would be the least fluid (i.e., most stiff)?
long, saturated fatty acid tails and cholesterol
Where are new phospholipids made?
endoplasmic reticulum
Detergent molecules are ___________ in nature and bind with membrane proteins and membrane lipids to disrupt their interactions and release the proteins from the membrane.
amphipathic
In a fluorescence recovery after photobleaching (FRAP) experiment, a fluorescently tagged membrane protein, A, shows very little recovery of fluorescence ten minutes after photobleaching, while membrane protein B shows a rapid increase in fluorescence after bleaching, recovering nearly 80% of its original fluorescent signal by ten minutes. Based on this information, which of the following statements can be made?
Protein B is diffusing in a more fluid membrane.
Which type of movement is the least common for lipids in a bilayer?
flip-flop
How is the protein shown in the diagram associated with the plasma membrane?
It is associated with one layer of the lipid bilayer.
Study Notes
Plasma Membrane Characteristics
- The plasma membrane is not commonly composed of a specific macromolecule (not specified).
Transport Proteins
- Proteins that facilitate active transport of ions in and out of cells are called plasma membrane proteins.
Phospholipid Dynamics
- When a vesicle fuses with the plasma membrane, phospholipids from the outer layer of the vesicle will end up on the outer layer of the plasma membrane.
Membrane Fluidity
- The fluidity of a membrane is increased by certain factors (not specified).
- A cell membrane primarily composed of lipids with saturated fatty acid tails and no double bonds would be the least fluid (i.e., most stiff).
Phospholipid Synthesis
- New phospholipids are made in the endoplasmic reticulum (not specified).
Detergent Interactions
- Detergent molecules are amphipathic in nature, allowing them to bind with membrane proteins and lipids, disrupting their interactions and releasing proteins from the membrane.
Fluorescence Recovery After Photobleaching (FRAP)
- In a FRAP experiment, a fluorescently tagged membrane protein with little recovery of fluorescence after photobleaching is likely to be immobile or have limited lateral mobility.
- A protein with a rapid increase in fluorescence after bleaching, recovering nearly 80% of its original signal, is likely to be highly mobile and able to diffuse freely.
Lipid Movement
- The least common type of movement for lipids in a bilayer is lateral movement (not specified).
Protein Association
- The protein shown in the diagram is associated with the plasma membrane through a transmembrane domain, which spans the entire membrane.
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