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TLS Online TPP Program

#Question id: 1262

Although MAP kinase is often activated in multicellular animals by RTKs or cytokine receptors, signaling from other receptors can activate MAP kinase in other eukaryotic cells. we consider the mating pathway in the yeast S. cerevisiae, a well-studied example of a MAP kinase cascade linked to G protein–coupled receptors (GPCRs). Which of the following statement is incorrect?

#Unit 4. Cell Communication and Cell Signaling

  1. An a haploid cell secretes the a mating factor and has GPCRs for the α factor on its cell surface; an α cell secretes the α factor and has GPCRs for the a factor. Thus each type of cell recognizes the mating factor produced by the opposite type.

  2. Ligand binding and dissociation of the G protein subunits, the membrane-tethered Gβγ subunit binds the Ste5 scaffold to the plasma membrane.

  3. Gβγ also activates Cdc24, a GAP for the Ras-like protein Cdc42; the active, GTP-bound Cdc42, in turn, binds to and activates the Ste20 kinase.

  4. Ste20 then phosphorylates and activates Ste11, which is analogous to Raf and other mammalian MEK kinase (MEKK) proteins. Ste20 thus serves as a MAPKKK kinase.

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TLS Online TPP Program

#Question id: 11186

#Unit 1. Molecules and their Interaction Relevant to Biology

Refer to the following graph of an action potential to answer the question. The membrane potential is closest to the equilibrium potential for potassium at label ________.
TLS Online TPP Program

#Question id: 11187

#Unit 7. System Physiology – Animal

Refer to the following graph of an action potential to answer the question.



The membrane's permeability to sodium ions is greatest at label ________.
TLS Online TPP Program

#Question id: 11188

#Unit 7. System Physiology – Animal

Refer to the following graph of an action potential to answer the question.

The minimum graded depolarization needed to operate the voltage-gated sodium and potassium channels is indicated by the label ________.
TLS Online TPP Program

#Question id: 11189

#Unit 7. System Physiology – Animal

Refer to the following graph of an action potential to answer the question.

At label ________, the cell is not hyperpolarized; however, repolarization is in progress, as the sodium channels are inactivated or becoming inactivated, and many potassium channels have opened.
TLS Online TPP Program

#Question id: 11190

#Unit 7. System Physiology – Animal

For a neuron with an initial membrane potential at -70 mV, an increase in the movement of potassium ions out of that neuron's cytoplasm would result in the ________.
TLS Online TPP Program

#Question id: 11191

#Unit 7. System Physiology – Animal

Opening all of the sodium channels on an otherwise typical neuron, with all other ion channels closed (which is an admittedly artificial setting), should move its membrane potential to ________.