BLY CH 9 Homework Assignment

According to Figure 9.11, which of the following is NOT responsible for amplifying the signal in a cell responding to adrenaline signaling? One molecule of adenylyl cyclase can produce many molecules of cAMP. One adrenaline molecule can bind to and activate many receptors simultaneously. One molecule of protein kinase A can phosphorylate and activate many target proteins. One activated receptor can activate many G proteins.

One adrenaline molecule can bind to and activate many receptors simultaneously.

Why do the functions of many receptor kinases depend on the fluid nature of the plasma membrane? Binding of ligand to the receptor requires a fluid membrane. The receptor monomers must move together and dimerize to be activated. Phosphorylation requires a fluid membrane. The generation of cAMP requires a fluid membrane.

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

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 responding cell None of the other answer options is correct. a signaling molecule a signaling cell a receptor protein

a receptor protein

Kohler and Lipton first discovered platelet-derived growth factor by observing that fibroblasts: could not grow in cell culture without adding PDGF to the growth medium. could not grow and repair wounding without the action of platelets. could not grow in cell culture without the addition of purified red blood cells. could not grow in cell culture without adding bovine blood serum to the growth medium. grew better in cell culture when blood serum from clotted blood was added to the growth medium instead of blood plasma from unclotted blood

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

Platelet-derived growth factor (PDGF) is a signaling molecule that functions in which of the following types of cell signaling? autocrine All of these choices are correct. contact-dependent paracrine endocrine

paracrine

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

All of these choices are correct.

According to Figure 9.6, what is a key difference between cell signaling by a cell-surface receptor and cell signaling by an intracellular receptor? None of the other answer options is correct. Cell-surface receptors bind to specific signaling molecules; intracellular receptors bind any signaling molecule. Cell-surface receptors typically bind to signaling molecules that are smaller than those bound by intracellular receptors. Signaling molecules that bind to cell-surface receptors lead to cellular responses restricted to the cytoplasm; signaling molecules that bind to intracellular receptors lead to cellular responses restricted to the nucleus. Cell-surface receptors bind polar signaling molecules; intracellular receptors bind nonpolar signaling molecules.

Cell-surface receptors bind polar signaling molecules; intracellular receptors bind nonpolar signaling molecules.

Which type of receptor is involved in rapid responses of muscle cells and neurons? G protein-coupled receptor intracellular receptor ligand-gated ion channel receptor kinase

ligand-gated ion channel

According to Figure 9.14, phosphate groups play a key role in receptor kinase activation by: activating the dimerization of the receptor kinase proteins in the membrane. All of these choices are correct. activating receptor kinase activity. activating the receptor, so that the receptor is capable of binding its signal. providing binding sites to recruit and activate signal-transduction proteins.

providing binding sites to recruit and activate signal-transduction proteins.