BLY 121 CH 9 LaunchPad

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

signal transduction results in:

a response by the cell

many diseases are the result of a problem with cell signaling. what disease best exemplifies this fact?

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

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

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?

notch is a receptor and delta is a signaling molecule

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

how do mitogen-activated protein (MAP) kinases become inactive?

phosphatases remove phosphate groups

what determines the specificity of a receptor protein?

the ligand-binding site

signaling molecules involved in paracrine and autocrine signaling:

travel by diffusion

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. All of these choices are correct. Delta directly signals to a Notch transmembrane protein in adjacent cells. Delta is a transmembrane protein found in embryonic brain cells.

All of these choices are correct.

why are some mutations of RAS associated with cancer?

RAS activates the MAP kinase signal transduction pathway

Why do the functions of many receptor kinases depend on the fluid nature of the plasma membrane?

The receptor monomers must move together and dimerize to be activated.

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

a change in gene expression

If two signaling pathways are activated simultaneously: they may strengthen each other they may inhibit each other one may inhibit the other all of the above

all of the above

what happens to the alpha subunit of a G protein with GDP attached? it reassembles with the beta and gamma subunits it no longer activates and effecter protein it re associates with the G protein-coupled receptor all of the above

all of the above

which signaling system involves the longest time interval between release of a signaling molecule and activation of a receptor?

endocrine

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

ligand-gated ion channel

what is the correct order for the steps in cell signaling?

receptor activation, signal transduction, response

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

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

steroid hormones are non polar and therefor are able to cross the cell's plasma membrane, binding to the receptors inside the cell

GTP binding occurs on which subunit of a G protein?

the alpha subunit

imagine that a researcher is studying the embryonic development of mice that do not express the signal molecule delta. what will likely be true of these mice?

the mice will have fewer glia compared to their normal counterparts

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

the presence of the appropriate receptor on the cells of the target tissue or organ

in the G protein-coupled signal transduction pathway, phosphatases are responsible for the inactivation of:

the protein target and activated by protein kinase A

a researcher introduces a signal produced by bacteria to eukaryotic cells that she is culturing in the lab. remarkably, she notices that the signal results in eukaryotic gene expression. how is this possible?

the signal is either similar in structure to a ligand used by eukaryotes, or the 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, non polar 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

which of the following is NOT a true statement about receptors that are localized to the nucleus? they bind polar ligands they move through a nuclear pore they are synthesized in the cytosol they carry a nuclear-localization signal

they bind polar ligands