Ch. 9 LaunchPad BLY 121

The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on:

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:

the receptor is activated

What is the end-result of activating the MAP kinase pathway?

A change in gene expression

A protein on a cell surface that binds to a signaling molecule is an example of which of the following elements of cellular communication?

A receptor protein

In the context of cell signaling, to what does the term ligand refer?

A signaling molecule

Many diseases are the result of a problem with cell signaling. Which of the following diseases best exemplifies this fact? -Congestive heart failure, caused by chronic high blood pressure due to excessive sodium intake. -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. -Familial hypercholesterolemia (high cholesterol in the blood), caused by a decrease in the number of receptors for cholesterol.

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

The signaling molecule involved in contact-dependent cell signaling is:

A transmembrane protein

What does a ligand-gated channel do?

It allows ions to move across the plasma membrane.

Which of the following statements is NOT true regarding a neurotransmitter? Neurotransmitters can be growth factors. Like Delta or Notch, neurotransmitters are usually attached to the cell surface. Neurotransmitters are produced by neurons. Neurotransmitters are typically dispersed over small distances. Neurotransmitters play a role in muscle contraction.

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

Why are some mutations of Ras associated with cancer?

Ras activates the MAP kinase signal transduction pathway.

Signal amplification relies on:

a sequential increase in the different components of the signal transduction pathway.

What is a growth factor?

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

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?

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

Why don't steroid hormones bind to transmembrane cell-surface receptors?

Steroid hormones are nonpolar and therefore are able to cross the cell's plasma membrane, binding to receptors inside the cell.

Which one of the following is not a cell surface-type receptor? G protein-coupled receptor steroid receptor ligand-gated receptor receptor kinase

Steroid receptor

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?

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

A researcher introduces a signal produced by bacteria to eukaryotic cells that she is culturing in the laboratory. Remarkably, she notices that this signal results in an increase in eukaryotic gene expression. How is this possible?

The signal is either similar in structure to a ligand used by eukaryotes, or this signaling pathway is utilized by both prokaryotes and eukaryotes.

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?

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? This ligand likely has a similar structure to cholesterol. This ligand likely binds to a transmembrane receptor. This ligand likely plays a role in transcription. This ligand is likely nonpolar. This ligand is likely a steroid.

This ligand likely binds to a transmembrane receptor.

What is one of the possible cellular responses following activation of the MAP kinase pathway?

a change in gene expression resulting in cell division

Which of the following is a cellular response to signal transduction?

a change in the proteins found in the cytosol the release of more signal molecules a change in the activity of an enzyme

What is the very first effect of ligand binding to a G protein-coupled receptor?

a conformational change in the cytoplasmic domain of the receptor

The activation of protein kinase A by cyclic AMP binding likely occurs because of:

a conformational change to protein kinase A.

Which of the following is TRUE about the Delta protein? Delta is produced by embryonic stem cells as they differentiate into neurons in the brain. Delta directs adjacent cells to differentiate into glial cells. Delta is a transmembrane protein found in embryonic brain cells. Delta directly signals to a Notch transmembrane protein in adjacent cells.

all are correct

Inactivation of a cell-surface receptor depends on:

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

Ligand binding to a receptor kinase results in:

phosphorylation of the cytoplasmic domain of the receptor. binding of cytoplasmic signaling molecules. receptor dimerization.

Where would you expect to find the receptor for a nonpolar ligand?

either in the nucleus of the cell or in the cytosol

Cell signaling over a long distance is known as:

endocrine signaling

Kohler and Lipton first discovered platelet-derived growth factor by observing that fibroblasts:

grew better in cell culture when blood serum from clotted blood was added to the growth medium instead of blood plasma from unclotted blood

Cellular responses that result from receptor kinase activation tend to:

involve changes in gene expression.

In cell communication, which one of the following is a requirement of the responding cell?

it must have receptor proteins

Which type of protein adds a phosphate group to another molecule?

kinase

Which type of receptor is involved in rapid responses of muscle cells and neurons?

ligand-gated ion channel

Platelet-derived growth factor (PDGF) is a signaling molecule that functions in which of the following types of cell signaling

paracrine

Growth factors such as platelet-derived growth factor function in:

paracrine signaling

A researcher is using a small molecule as an inhibitor to manipulate a signaling pathway. This inhibitor prevents phosphorylation and most likely targets a:

receptor kinase

Which type of cell-surface receptor undergoes changes in phosphorylation in response to binding of its ligand?

receptor kinase

Cyclic AMP (cAMP) is an example of a(n):

second messenger

Which of the following is not an essential element involved in communication between all cells? Please choose the correct answer from the following choices, and then select the submit answer button. responding cell second messenger signaling molecule receptor protein

second messenger

GTP binding occurs on which subunit of a G protein?

the alpha subunit

In order for a G protein to be active:

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

Cell signaling between two nerve cells can be thought of as an example of paracrine signaling because:

the cells are close in proximity

What determines the specificity of a receptor protein?

the ligand-binding site

How does an "activated" receptor transfer information into the cell?

through a conformational change of the receptor

Signaling molecules involved in paracrine and autocrine signaling:

travel by diffusion