TLS Online TPP Program

#Question id: 4660


Two-component system regulating response to low Gln,

a) Glutamine dissociates from the sensor domain in the NtrB protein, leading to activation of a histidine kinase transmitter domain in NtrB

b) glutamine binds to a sensor domain of NtrB, causing a conformational change in the protein that inhibits its histidine kinase activity, the regulatory domain of NtrC blocks its DNA-binding domain from binding the glnA enhancers.

c) Activated transmitter domain of NtrB that transfers the γ-phosphate of ATP to a histidine residue (H), this phosphohistidine then transfers the phosphate to an aspartic acid residue (D) in the NtrC protein

d) This causes a conformational change in NtrC that unmasks the NtrC DNA-binding domain so that it can bind to the glnA enhancers

Which of the following combination is correct?

#Unit 3. Fundamental Processes
  1. B, C and D

  2. A, C, and D

  3. B and D only

  4. C and D only

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TLS Online TPP Program

#Question id: 11216

#Unit 7. System Physiology – Animal

When two excitatory postsynaptic potentials (EPSPs) occur at a single synapse so rapidly in succession that the postsynaptic neuron's membrane potential has not returned to the resting potential before the second EPSP arrives, the EPSPs add together producing ________.

TLS Online TPP Program

#Question id: 11215

#Unit 7. System Physiology – Animal

If excitatory postsynaptic potentials (EPSPs) are produced nearly simultaneously through two different synapses on the same postsynaptic neuron, the EPSPs can also add together creating ________.

TLS Online TPP Program

#Question id: 11214

#Unit 7. System Physiology – Animal

Neurotransmitters categorized as inhibitory are expected to ________.

TLS Online TPP Program

#Question id: 11213

#Unit 7. System Physiology – Animal

An example of ligand-gated ion channels is ________.

TLS Online TPP Program

#Question id: 11212

#Unit 7. System Physiology – Animal

The activity of acetylcholine in a synapse is terminated by its ________.

TLS Online TPP Program

#Question id: 11211

#Unit 7. System Physiology – Animal

The following steps refer to various stages in transmission at a chemical synapse.


1. Neurotransmitter binds with receptors associated with the postsynaptic membrane.


2. Calcium ions rush into neuron's cytoplasm.


3. An action potential depolarizes the membrane of the presynaptic axon terminal.


4. The ligand-gated ion channels open.


5. The synaptic vesicles release neurotransmitter into the synaptic cleft.


Which sequence of events is correct?