Cell Communication: Chp 11

Question 1

what are the three stages to cell signaling

Answer 1

reception, transduction, and response

Question 2

reception

Answer 2

the target cell’s detection of a signal molecule coming from outside the cell

Question 3

transduction

Answer 3

the conversion of the signal to a form that can bring about a specific response

Question 4

response

Answer 4

the specific cellular response to the signal molecule

Question 5

intracellular receptors

Answer 5

found inside the plasma membrane in the cytoplasm or nucleus

Question 6

plasma membrane receptors

Answer 6

bind to water-soluble ligands

Question 7

G protein-coupled receptor

Answer 7

a membrane receptor that works with the help of a G protein

Question 8

Steps for how the G protein-coupled receptor and G protein work together

Answer 8

1: the pigand or signaling molecule binds to the G protein-coupled receptor. this causes a confornmational change in the receptor so that it may now bind to an inactive G protein, causing a GTP to displace the GDP activating the G protein.
2: the G protein binds to a specific enzyme and activates it. when the enzyme is activated, it can trigger the next step in a pathway leading to a cellular response. all the molecular shape changes are temporary. to continue the response new signal molecules are required.

Question 9

receptor tyrosine kinase steps

Answer 9

1: the binding of signal molecules to the receptors and the subsequent formation of a dimer. in the dimer confiduration each tyrosine kinase adds a phosphate from an ATP molecule
2: the fully activated receptor protein initiates a uniqu cellular response for each phosphorylated tyrosine.
* The ability of a single ligand to activate multiple cellular responses is a key difference between G protein-coupled receptors and receptor tyrosine kinases

Question 10

phosphorylation cascade

Answer 10

a multistep pathway that amplifies the signal that exists

Question 11

protein kinases

Answer 11

the enzymes that at each step phosphorylate and thereby activate many proteins at the next level. this cascade of phosphorylation greatly enhances the signal, allowing for a large cellular response

Question 12

protein phosphtases

Answer 12

enzymes that remove phosphate groups and inactive protein kinases. thus, the signal can be turned on by kinases, and off by phosphatases

Question 13

second messengers

Answer 13

small, nonprotein water-soluble molecules or ions. once they are activated they initiate a phosphorylation cascade resulting in a cellular response

Question 14

apoptosis

Answer 14

cell suicide. it is triggered by signals that activate a cascade of “suicide” proteins in the cells