Chapter 9 LC

In the developing nervous system, _____ is the signaling molecule that results in the differentiation of _____. Please choose the correct answer from the following choices, and then select the submit answer button. Delta; neurons Notch; neurons Notch; glial cells Delta; glial cells

Delta; glial cells

In the context of cell signaling, to what does the term ligand refer? Please choose the correct answer from the following choices, and then select the submit answer button. the proteins activated as part of a signal transduction pathway the extracellular domain of a receptor protein a type of gated channel a signaling molecule

a signaling molecule

The signaling molecule involved in contact-dependent cell signaling is: Please choose the correct answer from the following choices, and then select the submit answer button. a transmembrane protein. 2.3 a growth factor. a small soluble peptide. a neurotransmitter.

a transmembrane protein.

Recall from the text the example of cell communication in Streptococcus pneumoniae: the rate of DNA uptake by pneumococcal cells increases sharply when they are at high density due to changes in gene expression brought about by signaling between cells. If the pneumococcal cells did not express receptor protein, how would the rate of DNA uptake be affected when the cells reach high density? Please choose the correct answer from the following choices, and then select the submit answer button. There would be a larger than normal increase in the rate of DNA uptake. There would be a decrease in the rate of DNA uptake. There would be no change in the rate of DNA uptake. There would be a smaller than normal increase in the rate of DNA uptake.

There would be no change in the rate of DNA uptake.

Many diseases are the result of a problem with cell signaling. Which of the following diseases best exemplifies this fact? Please choose the correct answer from the following choices, and then select the submit answer button. Familial hypercholesterolemia (high cholesterol in the blood), caused by a decrease in the number of receptors for cholesterol. Cystic fibrosis, caused by a mutation in a channel protein, resulting in a buildup of mucus. A specific type of cancer, caused by a truncated receptor that becomes stuck in the activated form. Congestive heart failure, caused by chronic high blood pressure due to excessive sodium intake.

A specific type of cancer, caused by a truncated receptor that becomes stuck in the activated form.

If two signaling pathways are activated simultaneously: Please choose the correct answer from the following choices, and then select the submit answer button. they may strengthen each other. they may inhibit each other. one may inhibit the other. All of these choices are correct.

All of these choices are correct.

Ligand binding to a receptor kinase results in: Please choose the correct answer from the following choices, and then select the submit answer button. phosphorylation of the cytoplasmic domain of the receptor. binding of cytoplasmic signaling molecules. receptor dimerization. All of these choices are correct.

All of these choices are correct.

Termination is an important step in adrenaline signaling because: Please choose the correct answer from the following choices, and then select the submit answer button. it prevents an excessive response to adrenaline. it allows organisms to respond to new stresses. it allows an appropriate level of response. All of these choices are correct.

All of these choices are correct.

What is a growth factor? Please choose the correct answer from the following choices, and then select the submit answer button. a small protein that influences cell growth and division a signaling molecule involved in paracrine signaling a soluble molecule that can alter gene expression in a cell All of these choices are correct.

All of these choices are correct.

Which of the following is a cellular response to signal transduction? Please choose the correct answer from the following choices, and then select the submit answer button. a change in the proteins found in the cytosol the release of more signal molecules a change in the activity of an enzyme All of these choices are correct.

All of these choices are correct.

What does a ligand-gated channel do? Please choose the correct answer from the following choices, and then select the submit answer button. It triggers the activity of a phosphatase. It binds small, nonpolar signaling molecules. It allows ions to move across the plasma membrane. It activates a G protein.

It allows ions to move across the plasma membrane.

In cell communication, which one of the following is a requirement of the responding cell? Please choose the correct answer from the following choices, and then select the submit answer button. It must be a eukaryotic cell. It must have receptor proteins. It must be a prokaryotic cell. It must produce signaling molecules.

It must have receptor proteins.

Which of the following statements is not true regarding a neurotransmitter? Please choose the correct answer from the following choices, and then select the submit answer button. Neurotransmitters play a role in muscle contraction. Neurotransmitters are produced by neurons. Neurotransmitters are typically dispersed over small distances. Like Delta or Notch, neurotransmitters are usually attached to the cell surface. Neurotransmitters can be growth factors.

Like Delta or Notch, neurotransmitters are usually attached to the cell surface.

Notch and Delta are both transmembrane proteins involved in cell communication in the developing nervous system of vertebrate animals. What makes Notch different from Delta? Please choose the correct answer from the following choices, and then select the submit answer button. Notch is a receptor and Delta is a signaling molecule. Notch is a signaling molecule and Delta is a receptor. Notch is required at higher density than Delta to alter cell fate. All of these choices are correct.

Notch is a receptor and Delta is a signaling molecule.

How do mitogen-activated protein (MAP) kinases become inactive? Please choose the correct answer from the following choices, and then select the submit answer button. Phosphatases remove phosphate groups. Ligand diffuses away from the ligand-binding site. Receptor kinases move apart in the membrane. Ras hydrolyzes GTP to GDP.

Phosphatases remove phosphate groups.

What causes the inactivation of a G protein? Please choose the correct answer from the following choices, and then select the submit answer button. The alpha subunit catalyzes the hydrolysis of GTP to GDP and inorganic phosphate. The inactive receptor catalyzes the replacement of GTP by GDP. A phosphatase removes the inorganic phosphate group from GTP. The beta and gamma subunits trigger the hydrolysis of GTP to GDP.

The alpha subunit catalyzes the hydrolysis of GTP to GDP and inorganic phosphate.

During the signal transduction process, the signal often triggers a signal transduction cascade. For example: An activated receptor activates hundreds of protein A. Each activated protein A activates hundreds of protein B and so on until a cellular response occurs. What purpose does this cascade serve? Please choose the correct answer from the following choices, and then select the submit answer button. The cascade serves to amplify the signal, so one activated receptor can have a significant response. Having several intermediates allows for greater control of the response. Having a cascade allows the cell to respond to different signals. The cascade makes signaling easier to shut off or terminate.

The cascade serves to amplify the signal, so one activated receptor can have a significant response.

Many scientists use chemical inhibitors to interfere with normal signaling pathways within eukaryotic cells. If such inhibitors are large, nonpolar molecules, what is the likely method of action of these chemical inhibitors? Please choose the correct answer from the following choices, and then select the submit answer button. These chemical inhibitors likely bind to receptors and interfere with receptor activation or signal-receptor binding. These chemical inhibitors likely interfere with the termination of signaling, so eukaryotic cells can't process new signals. These chemical inhibitors likely enter eukaryotic cells and interfere with components of the signal transduction pathway. These chemical inhibitors likely enter the nucleus and prevent the transcription of the pathway of interest's target genes.

These chemical inhibitors likely bind to receptors and interfere with receptor activation or signal-receptor binding.

A researcher has discovered a new ligand that can pass through the cell membrane and bind to a receptor in the nucleus. Which of the following statements is not likely true of this ligand? Please choose the correct answer from the following choices, and then select the submit answer button. This ligand likely plays a role in transcription. This ligand likely has a similar structure to cholesterol. This ligand likely binds to a transmembrane receptor. This ligand is likely a steroid. This ligand is likely nonpolar.

This ligand likely binds to a transmembrane receptor.

What is the cell's likely response to ligand binding to a steroid receptor located in the nucleus? Please choose the correct answer from the following choices, and then select the submit answer button. a change in gene expression activation of a kinase change in ion transport initiation of a signal transduction pathway

a change in gene expression

The activation of protein kinase A by cyclic AMP binding likely occurs because of: Please choose the correct answer from the following choices, and then select the submit answer button. the binding of GTP to protein kinase A. a conformational change to protein kinase A. the activity of a phosphatase. the phosphorylation of protein kinase A.

a conformational change to protein kinase A.

Inactivation of a cell-surface receptor depends on: Please choose the correct answer from the following choices, and then select the submit answer button. the binding affinity of the receptor. the activity of phosphatases in the cytosol. the concentration of ligand surrounding the cell. both the binding affinity of the receptor and concentration of ligand surrounding the cell.

both the binding affinity of the receptor and concentration of ligand surrounding the cell.

Which signaling system involves the longest time interval between release of a signaling molecule and activation of a receptor? Please choose the correct answer from the following choices, and then select the submit answer button. paracrine endocrine contact-dependent autocrine

endocrine

Cell signaling over a long distance is known as: Please choose the correct answer from the following choices, and then select the submit answer button. contact-dependent signaling. endocrine signaling. paracrine signaling. autocrine signaling.

endocrine signaling.

The presence of excess EGF receptors can result in: Please choose the correct answer from the following choices, and then select the submit answer button. diminished cell division. normal cell division. excessive cell division.

excessive cell division.

Which type of protein adds a phosphate group to another molecule? Please choose the correct answer from the following choices, and then select the submit answer button. phosphorylase phosphatase kinase G protein

kinase

Which is the correct order for these steps in cell signaling? Please choose the correct answer from the following choices, and then select the submit answer button. receptor activation, response, signal transduction signal transduction, receptor activation, response response, signal transduction, termination receptor activation, signal transduction, response

receptor activation, signal transduction, response

In many signaling pathways, once a signaling molecule binds to a receptor, the receptor becomes phosphorylated. This initial phosphorylation step best demonstrates: Please choose the correct answer from the following choices, and then select the submit answer button. either cellular response or signal transduction. termination. signal transduction. receptor activation.

receptor activation.

In many signaling pathways, once a signaling molecule binds to a receptor, the receptor becomes phosphorylated. This initial phosphorylation step best demonstrates: Please choose the correct answer from the following choices, and then select the submit answer button. either cellular response or signal transduction. termination. signal transduction. receptor activation. cellular response.

receptor activation.

Which type of cell-surface receptor undergoes changes in phosphorylation in response to binding of its ligand? Please choose the correct answer from the following choices, and then select the submit answer button. both the G protein-coupled receptor and the receptor kinase G protein-coupled receptor ligand-gated ion channel receptor kinase

receptor kinase

A researcher is using a small molecule as an inhibitor to manipulate a signaling pathway. This inhibitor prevents phosphorylation and most likely targets a: Please choose the correct answer from the following choices, and then select the submit answer button. G protein. ligand-gated ion channel. phosphatase. receptor kinase. G protein-coupled receptor.

receptor kinase.

Which one of the following is not a cell surface-type receptor? Please choose the correct answer from the following choices, and then select the submit answer button. ligand-gated receptor G protein-coupled receptor receptor kinase steroid receptor

steroid receptor

In order for a G protein to be active: Please choose the correct answer from the following choices, and then select the submit answer button. the alpha subunit must bind GTP and the beta and gamma subunits must separate from the alpha subunit. the beta and gamma subunits must separate from the alpha subunit. both the beta and gamma subunits must bind GTP. the alpha subunit must bind GTP.

the alpha subunit must bind GTP and the beta and gamma subunits must separate from the alpha subunit.

Ras is most similar to: Please choose the correct answer from the following choices, and then select the submit answer button. ion channels. the beta subunit of three-subunit G proteins. receptor kinases. the gamma subunit of three-subunit G proteins. the alpha subunit of three-subunit G proteins.

the alpha subunit of three-subunit G proteins.

Cell signaling between two nerve cells can be thought of as an example of paracrine signaling because: Please choose the correct answer from the following choices, and then select the submit answer button. the cells are in close proximity. a receptor is activated. the responding cell releases more signaling molecule (neurotransmitter). a signaling molecule (neurotransmitter) is released.

the cells are in close proximity.

The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on: Please choose the correct answer from the following choices, and then select the submit answer button. the membrane potential of the cells of the target organ. the presence of the appropriate receptors on the cells of the target tissue or organ. nothing; all hormones of the body are able to stimulate all cell types because hormones are powerful and nonspecific. the location of the tissue or organ with respect to the circulatory path.

the presence of the appropriate receptors on the cells of the target tissue or organ.

The first event that happens after a signaling molecule binds to a receptor is: Please choose the correct answer from the following choices, and then select the submit answer button. the receptor is activated. the signal is quickly terminated to ensure a moderate response. there is a cellular response. the receptor transmits the message in a process called signal transduction.

the receptor is activated.

How many subunits make up some types of G protein? Please choose the correct answer from the following choices, and then select the submit answer button. six four two three five

three

Signaling molecules involved in paracrine and autocrine signaling: Please choose the correct answer from the following choices, and then select the submit answer button. remain attached to the plasma membrane. travel by diffusion. travel in the circulatory system.

travel by diffusion.

Cancer is a disease of cell division. Please choose the correct answer from the following choices, and then select the submit answer button. true false

true

Signaling pathways have been conserved in a wide range of organisms. Please choose the correct answer from the following choices, and then select the submit answer button. true false

true