A researcher studying bacterial toxin predicts that a lysine within the toxin is important for binding it’s target cell.  She used site-directed mutagenesis to change a codon for lysine (AAA) to one for asparagine (AAU).  However, the mutant toxin still binds to its target cell just as well as the wild-type toxin bound and appears to have no other changes. This type of mutation is probably

#Question id: 1393

#Unit 4. Cell Communication and Cell Signaling

In research on aging (both cellular aging and organismal aging), it has been found that aged cells do not progress through the cell cycle as they had previously. Which of the following, if found in cells or organisms as they age, would provide evidence that this is related to cell signalling?

#Question id: 1394

#Unit 4. Cell Communication and Cell Signaling

Apoptosis involves all but which of the following?

#Question id: 1395

#Unit 4. Cell Communication and Cell Signaling

Which of the following mutations would promote malignancy in cells whose proliferation is inhibited by TGFβ?

a. overexpression of Smad2               

b. loss of Smad 4

c. overexpression of TGFβ receptor I

d. loss of TGFβ receptor II

#Question id: 1396

#Unit 4. Cell Communication and Cell Signaling

Trks are:

a. endonucleases.        b. transmembrane receptors.   c. proteases.     d. protein kinases.      

#Question id: 1397

#Unit 4. Cell Communication and Cell Signaling

The vertebrate equivalent of CED-9 is:

#Question id: 1398

#Unit 4. Cell Communication and Cell Signaling

Which of the following properties is (are) characteristic of a benign tumor?

a. well differentiated              b. localized to tissue of origin             c. metastatic               

d. promotes angiogenesis        e. surrounded by a fibrous capsule