3D Flashcards
What is the composition of a membrane bilayer?
A membrane bilayer consists of phospholipids and proteins.
What are the dynamics and organization of membrane bilayers?
Membrane bilayers are dynamic structures that can change shape and organization.
What are membrane proteins?
Membrane proteins are proteins that are embedded in or associated with the lipid bilayer of a membrane.
How can the diffusion of membrane proteins be measured?
Diffusion can be measured using techniques like FRAP (Fluorescence Recovery After Photobleaching).
What is lateral diffusion of membrane proteins?
Lateral diffusion refers to the movement of proteins within the plane of the membrane.
What is the characteristic of _______ diffusion in membrane proteins?
Free or unrestrained diffusion.
What is the characteristic of _______ diffusion in membrane proteins?
No or negligible diffusion.
What is the characteristic of _______ diffusion in membrane proteins?
Restricted or partial diffusion.
Provide an example of limited diffusion in cells.
Polarized epithelial cells.
What separates the apical and basal membranes in epithelial cells?
Tight junctions.
What is the role of the tight junction?
It separates the apical and basal membranes in epithelial cells.
Which Nobel Prize winner is associated with tight junction research?
George Palade.
What are the functions of the apical and basal membranes?
They have distinct compositions and functions despite being contiguous.
What is the function of the NA-K ATPase?
It is localized to the basolateral membrane.
What is the role of aquaporins?
They function as water transporters in the apical membrane.
What are mechanisms that restrict membrane protein movement?
Self-assembly into complexes, tethering to the extracellular matrix, tethering to the cytoskeleton, and interacting with proteins on other cells.
What structure gives red blood cells their biconcave shape?
Membrane protein interactions with the cortical cytoskeleton.
What is spectrin?
A protein that forms a mesh-like structure under the plasma membrane.
What are two integral membrane proteins that bind spectrin?
- Glycophorin
- Band 3
What does the spectrin cortical cytoskeleton do?
It interacts with membrane proteins and provides shape and structure to red blood cells.
What is the function of the junctional complex in red blood cells?
It cross-links spectrin filaments and connects them to the membrane.
What is the significance of restricted protein diffusion?
It is critical for the function of some cells, such as epithelial and sperm cells.
True or False: Most membrane proteins are free to diffuse throughout the entire cell membrane.
False.
What is indicated by the actual path of a single protein molecule in a membrane?
It indicates that the protein spends significant time diffusing within a corral.
What are the dimensions of corrals that restrict protein diffusion?
200-400 nm.
How does restricted diffusion occur in epithelial or endothelial cell layers?
Proteins are restricted from moving between apical and basolateral membranes.
What is the importance of studying the movement of individual protein molecules?
It reveals how molecules are controlled inside the cell.
