Module 4: Structure/Function of Plasma Membrane Flashcards
What are apical?
they are plasma membrane that absorb substances from the lumen.
What is lateral?
cell contact.
Basal?
Substratum contact, ion gradients
Function of antibodies with fluorescent tag?
They can detect and demonstrate the distribution of different proteins.
What is the best studied and well understood plasma membrane?
Human erythrocyte.
Define Spectrin:
They are major component of the internal membrane skeleton. They are also molecules are attached to the membrane surface to Ankyrin.
What are actin?
42 kDa protein – multifunctional, also present in microfilament.
What are Tropomyosin?
2-stranded (hetero or homodimer) alpha-helical coiled coil,
65 kDa, functions in microfilaments.
What are Ankyrin?
- Mediates interaction with integral membrane proteins such as Band-3, 206 kDa.
What are Glycophorin A?
Transmembrane dimer, each subunit is a single pass protein, heavily glycosylated about 1 million molecules/erythrocyte, first membrane protein to be sequenced.
What are Band 3-
Multipass homodimer, binds to ankyrin, functions as a HCO3-/Cl- exchanger
What are Band 4.1?
80 kDa protein that stabilizes actin-spectrin interactions in the erythrocyte membrane cytoskeleton.
What are G3PD?
Glyceraldehyde-3-phosphate dehydrogenase- 37 kDa - glycolysis.
Function of selective permeability?
Allows for separation and exchange of materials across the plasma membrane.
What is net flux?
Difference between influx and efflux of materials.
How do substances move around?
Move across membranes by diffusion and active transport.
What is osmosis?
Diffusion of water through a semipermeable membrane.
When do cells swell, shrink or remain unchanged?
They swell in hypotonic solution, shrink in hypertonic solutions and remain unchanged in isotonic solutions.
What do plant cell undergo in hypertonic solutions?
Plasmolysis.
What are voltage-gated channels?
Their conformational state depends on the difference in ionic charge on the two sides of the membrane.
What are ligand-gated channels?
Their conformational state depends on the binding of a specific molecule.
What are mechano-gated channels?
Their conformational state depends on mechanical forces that are applied to the membrane.
Function of the diffusion of ions via membranous-gated channels:
- Patch clamping llows for electrochemical study of single channel proteins.
- Once opened more than 10 million K+ ions can pass through per sec.
- After the channel is open for a few milliseconds, the movement of K+ ions is automatically stopped.
Can exists in 3 different states: open, inactivated, and rest.
What is facilitated diffusion?
They can mediate the movement of solutes in both directions. It is similar to an enzyme-catalyzed reaction.
What are active tranpoertrs?
A process that involves the movement of molecules from a region of lower concentration to a region of higher concentration against a gradient or an obstacle with the use of external energy.
What is the E1 and E2 conformations?
E1 - Ion binding sites which are accessible to the inside of the cell.
E2- Ion binding site which are accessible to the outside of the cell.
What is the best studied P-type pump?
The Ca2+-ATPase which is present in the ER to actively transport Ca2+ out of the cytosol into the lumen.
What transports H+ across the walls of cytoplasmic organelles?
Vascuolar (V)-type pump.
Function of Vascuolar (V)-type pump:
In the the plasma membranes of kidney tubules helps maintain the body’s acid-base balance by secreting protons into the forming urine.
What type of pump doe the stomach contains?
The P-type pump, and also H/K-ATPase, which secretes a solution of concentrated acid.
Retinal is a derivative of what type of vitamin?
Vitamin A.
How is Na+ concentration kept low?
By the Na+/K+-ATPase pump.
What drives the co-transport of glucose?
Diffusion of sodium ions down a concentration gradient.
What is an example of secondary active tranport?
Symport.
Functions of anti-porters or exchangers?
Move two transported species in opposite directions.
What happens to proteins during the transport cycle?
The proteins binding sites gain alternating access to the cytoplasm.
What are neurons?
They are specialized cells for information transmission using changes in membrane potentials.
What are dendrites?
They recieve incoming information.
What is the cell body?
Contains the nucleus and metabolic center of the cell.
What are axon?
A long extension for conducting outgoing impulses.
What is the resting potential?
Is the membrane potential of a nerve or muscle cell, subject to changes when activated.
What pump is responsible for maintaing the resting poteinal?
Na+/K+-ATPase.
What cause depolarization?
When cells are stimulated, Na+ channels open.
What triggers action potential?
When cells are stimulated voltage-gated Na+ channels open, triggering action potential.
What do excitable membranes exhibit?
All-or-none behaviour.
What does the spped of neural impulses depends on?
Axon diameter and whether axon is myelinated.
Where do Na ion channels of a myelinated neuron reside?
They reside in the unwrapped gaps, or nodes of Ranvier.
Where is the site where AP can be generated jumping from node to node?
The nodes of Ranvier.
Where do presynaptic neurons communicate with post-synaptic neurons?
The synapse, across the synaptic cleft.
Where are neurotransmitters released from?
The presynaptic cleft diffuse to receptors on the postsynaptic cell.
What happens when neurotranssmiter bind?
binding of neurotransmitters to ion channels receptors an either stimulate or inhibit action potential.
What does ACh inhibit/stimulate?
It inhibit heart contracticility but stimulates contractility of skeletal muscle.
What does glutamate serve as and gamma-aminobutyric acid (GABA)?
Glutamate serves as the primary excitatory and gamma-aminobutyric acid as the primary inhibitory neurotransmitter.
