Question 1

In unstimulated cells, NF-$\kappa$B proteins are maintained in an inactive state in the cytosol by interactions with

Accepted Answer

NF-$\kappa$B proteins are kept inactive in the cytosol by binding to I$\kappa$B proteins, which inhibit their translocation to the nucleus.

Question 2

An example of signaling by direct cell-cell interactions is the

Accepted Answer

The Notch pathway is an example of signaling by direct cell-cell interactions. Notch receptors on one cell interact with ligands on a neighboring cell, leading to a cascade of events that ultimately affect gene expression in the receiving cell. The other pathways listed (Wnt, JAK/STAT, vulval development in C. elegans) do not involve direct cell-cell interactions.

Question 3

Which of the following signaling pathways allows for direct cell-cell signaling by transmembrane proteins?

Accepted Answer

Notch signaling pathway involves direct cell-cell signaling by transmembrane proteins. The receptor protein on one cell binds to the ligand protein on an adjacent cell and initiates a signaling cascade within the cell.

Question 4

In what ways are steroid hormone receptors different from most other types of cellular receptors?

Accepted Answer

The answer of In what ways are steroid hormone receptors...

Question 5

In plants, growth can be mediated by what is frequently referred to as "auxin-induced transcription" of genes critical to growth. This terminology was derived from experiments demonstrating that the addition of auxin leads to an increase in the expression of genes responsible for growth. However, since auxin is not a transcription factor and cannot directly activate transcription, how does it regulate gene activity?

Accepted Answer

The answer of In plants, growth can be mediated by...

Question 6

What is the basis for the different responses of nerve cells versus heart muscle cells to acetylcholine?

Accepted Answer

The answer of What is the basis for the different...

Question 7

Why do enzymes that lie downstream of a cell surface receptor in a signal transduction pathway amplify as well as propagate the signal?

Accepted Answer

The answer of Why do enzymes that lie downstream of...

Question 8

As a cell biologist for a pharmaceutical company, you are charged with developing a drug to inhibit the cAMP response element binding protein (CREB) pathway. Briefly describe the cascade leading to CREB activation and where one might target a drug to block its activation.

Accepted Answer

The answer of As a cell biologist for a pharmaceutical...

Question 9

What are the hallmarks of the first steps in signaling through receptor tyrosine kinases?

Accepted Answer

The answer of What are the hallmarks of the first...

Question 10

Growth factors and cytokines both lead to tyrosine phosphorylation through receptors, but they do so through different mechanisms. What is the key difference between the receptors for these two classes of ligands in terms of their tyrosine kinase activity?

Accepted Answer

The answer of Growth factors and cytokines both lead to...

Question 11

Cytokine receptors frequently form dimers upon ligand binding, and these can be heterodimers or homodimers. Explain how this ability of the receptors to form different combinations of dimers allows three unique cytokines, each with a unique action, to arise from only two cytokine receptors.

Accepted Answer

The answer of Cytokine receptors frequently form dimers upon ligand...

Question 12

In the signaling of cells to initiate growth, immediate early genes become activated to initiate the growth process. What would happen to the expression of these immediate early genes if Elk-1 was not able to be dephosphorylated, and why?

Accepted Answer

The answer of In the signaling of cells to initiate...

Question 13

What would happen to NF-$\kappa$B signaling if I$\kappa$B were unable to be dephosphorylated?

Accepted Answer

The answer of What would happen to NF-$\kappa$B signaling if...

Question 14

Explain the concept of "feedback loops" in signaling networks.

Accepted Answer

The answer of Explain the concept of "feedback loops" in...

Quiz 17: Cell Signaling

In unstimulated cells, NF- $\kappa$ B proteins are maintained in an inactive state in the cytosol by interactions with

An example of signaling by direct cell-cell interactions is the

Which of the following signaling pathways allows for direct cell-cell signaling by transmembrane proteins?

In what ways are steroid hormone receptors different from most other types of cellular receptors?

What is the basis for the different responses of nerve cells versus heart muscle cells to acetylcholine?

Why do enzymes that lie downstream of a cell surface receptor in a signal transduction pathway amplify as well as propagate the signal?

As a cell biologist for a pharmaceutical company, you are charged with developing a drug to inhibit the cAMP response element binding protein (CREB) pathway. Briefly describe the cascade leading to CREB activation and where one might target a drug to block its activation.

What are the hallmarks of the first steps in signaling through receptor tyrosine kinases?

Growth factors and cytokines both lead to tyrosine phosphorylation through receptors, but they do so through different mechanisms. What is the key difference between the receptors for these two classes of ligands in terms of their tyrosine kinase activity?

Cytokine receptors frequently form dimers upon ligand binding, and these can be heterodimers or homodimers. Explain how this ability of the receptors to form different combinations of dimers allows three unique cytokines, each with a unique action, to arise from only two cytokine receptors.

In the signaling of cells to initiate growth, immediate early genes become activated to initiate the growth process. What would happen to the expression of these immediate early genes if Elk-1 was not able to be dephosphorylated, and why?

What would happen to NF- $\kappa$ B signaling if I $\kappa$ B were unable to be dephosphorylated?

Explain the concept of "feedback loops" in signaling networks.

Quiz 17: Cell Signaling

In unstimulated cells, NF- κ\kappaκ B proteins are maintained in an inactive state in the cytosol by interactions with

An example of signaling by direct cell-cell interactions is the

Which of the following signaling pathways allows for direct cell-cell signaling by transmembrane proteins?

In what ways are steroid hormone receptors different from most other types of cellular receptors?

What is the basis for the different responses of nerve cells versus heart muscle cells to acetylcholine?

Why do enzymes that lie downstream of a cell surface receptor in a signal transduction pathway amplify as well as propagate the signal?

As a cell biologist for a pharmaceutical company, you are charged with developing a drug to inhibit the cAMP response element binding protein (CREB) pathway. Briefly describe the cascade leading to CREB activation and where one might target a drug to block its activation.

What are the hallmarks of the first steps in signaling through receptor tyrosine kinases?

Growth factors and cytokines both lead to tyrosine phosphorylation through receptors, but they do so through different mechanisms. What is the key difference between the receptors for these two classes of ligands in terms of their tyrosine kinase activity?

Cytokine receptors frequently form dimers upon ligand binding, and these can be heterodimers or homodimers. Explain how this ability of the receptors to form different combinations of dimers allows three unique cytokines, each with a unique action, to arise from only two cytokine receptors.

In the signaling of cells to initiate growth, immediate early genes become activated to initiate the growth process. What would happen to the expression of these immediate early genes if Elk-1 was not able to be dephosphorylated, and why?

What would happen to NF- κ\kappaκ B signaling if I κ\kappaκ B were unable to be dephosphorylated?

Explain the concept of "feedback loops" in signaling networks.

In unstimulated cells, NF- $\kappa$ B proteins are maintained in an inactive state in the cytosol by interactions with

What would happen to NF- $\kappa$ B signaling if I $\kappa$ B were unable to be dephosphorylated?