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TLS Online TPP Program

#Question id: 10223

when plastoquinone is accumulates in the reduced state, Reduced plastoquinone accumulates when PSII is being activated more frequently than PSI. What will happen when plastoquinone becomes more oxidized?

#Unit 6. System Physiology – Plant
  1. The kinase is deactivated and the level of phosphorylation of LHCII is decreased by the action of a membrane-bound phosphatase
  2. The kinase is activated and then phosphorylate a specific threonine residue on the surface of LHCII
  3. phosphorylation of LHCII is take place and the phosphorylated LHCII then migrates out of the stacked regions of the membrane into the unstacked regions
  4. kinase is deactivated dephophorylation takes place and LHCII moves back to the stroma lamellae away from photosystem II
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TLS Online TPP Program

#Question id: 1220

#Unit 4. Cell Communication and Cell Signaling

Many G protein-coupled receptors contain seven transmembrane α-helical domains. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior surface or on the cytosolic surface of the membrane. The loop on the cytosolic side between helices 5 and 6 is usually substantially longer than the others. Where would a coupled G protein most likely interact with this receptor?
TLS Online TPP Program

#Question id: 1221

#Unit 4. Cell Communication and Cell Signaling

If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?
TLS Online TPP Program

#Question id: 1222

#Unit 4. Cell Communication and Cell Signaling

Particular receptor tyrosine kinases (RTKs) that promote excessive cell division are found at high levels in various cancer cells. HER2 is an RTK that is present at excessively high levels in some breast cancer cells. Herceptin is a protein that binds to HER2 and inhibits cell division. Herceptin may be an effective treatment for breast cancer treatment under which of the following conditions?
TLS Online TPP Program

#Question id: 1223

#Unit 4. Cell Communication and Cell Signaling

The receptors for steroid hormones are located inside the cell instead of the membrane surface like most other signal receptors. How do steroids gain access to their receptors?
TLS Online TPP Program

#Question id: 1224

#Unit 4. Cell Communication and Cell Signaling

Put the steps of the process of signal transduction in the order they occur.

1. A conformational change in the signal-receptor complex activates an enzyme.

2. Protein kinases are activated.

3. A signal molecule binds to a receptor.

4. Target proteins are phosphorylated.

5. Second messenger molecules are released.
TLS Online TPP Program

#Question id: 1225

#Unit 4. Cell Communication and Cell Signaling

The dissociation constant Kd for a receptor-ligand complex is

a. a measure of the affinity of the receptor for the ligand.

b. the concentration of the ligand at which half of the receptors contain bound ligand.

c. a measure of the time it takes for a ligand to be converted to a product.

d. equal to koff/kon