1.) NMDA receptors are different from AMPA receptors in that: NMDA receptors bin
ID: 3475820 • Letter: 1
Question
1.) NMDA receptors are different from AMPA receptors in that:
NMDA receptors bind extracellular glutamate whereas AMPA receptors do not.
NMDA receptor activation leads to an EPSP whereas AMPA receptor activation leads to an IPSP.
NMDA receptors are ligand-gated ion channels whereas AMPA receptors are G-protein-coupled receptors.
NMDA receptors are gated by both voltage and glutamate whereas AMPA receptors are gated only by voltage.
NMDA receptors are blocked by magnesium ions at Vr whereas AMPA receptors are not.
2.) Which of the following is true of early LTP?
AMPA-receptors are activated, resulting in a depolarization of the post-synaptic membrane.
NMDA-receptors are activated, resulting in calcium influx into the post-synaptic cell.
New proteins are synthesized, resulting in structural changes at the synapse(s).
Both (A) and (B) are true.
All of the above are true.
A.NMDA receptors bind extracellular glutamate whereas AMPA receptors do not.
B.NMDA receptor activation leads to an EPSP whereas AMPA receptor activation leads to an IPSP.
C.NMDA receptors are ligand-gated ion channels whereas AMPA receptors are G-protein-coupled receptors.
D.NMDA receptors are gated by both voltage and glutamate whereas AMPA receptors are gated only by voltage.
E.NMDA receptors are blocked by magnesium ions at Vr whereas AMPA receptors are not.
Explanation / Answer
1)e. NMDAs are inhibited by Mg2+ while AMPAs are not.
NMDA and AMPA bithe are ionotropic glutamate receptors which open upon binding of glutamate and glycine/d-serine to allow flow of ions (calcium, potassium and sodium in the former and only sodium and potassium in the latter). Hence they are primarily ligand gated but later shows voltage dependence (during the movement of ions). They allow cationic influx and hence cannot have opposite roles (of one initiating an EPSP while the other resulting in an IPSP).
2) e. All of the above
LTP stands for long term potentiation which is made possible by all the 3 options. Depolarization due to AMPA is the 1st thing that happens. Once the memebrane is sufficiently depolarized only then the Mg2+ block from the NMDAs is relieved resulting in influx of calcium which later (are a cascade) causes phophortlation as well as an increase in dendritic spine (this requires synthesis of new proteins). Both cause a stronger and faster response.
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