A bone marrow transplant may not be appropriate from a given donor (Jane) to a given recipient (Janeʹs cousin Bob), even though Jane has previously given blood for one of Bobʹs needed transfusions. Which of the following might account for this?

#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: 2903

#Unit 2. Cellular Organization

There are five known families of enzyme complexes that actively move or displace nucleosomes, hydrolyzing ATP in the process, three of which are particularly important in transcriptional activation. Which of the following statement is/are correct regarding these nucleosome remodeling complexes?

I. SWI/SNF remodels chromatin so that nucleosomes become more irregularly spaced, and stimulate the binding of transcription factors. It includes a bromodomain near the C-terminus of the active ATPase subunit, which interacts with acetylated histone tails.

II. Some members of a family, SWR1, are involved in deposition of the H2A.Z histone variant in transcriptionally inactive chromatin. 

III. NURF, a member of the ISW1 family, remodels chromatin in ways that complement and overlap the activity of SWI/SNF. These two enzyme complexes are crucial in preparing a region of chromatin for active transcription.

#Question id: 3026

#Unit 2. Cellular Organization

Not present in all bacteria, this structure enables those that possess it to germinate after exposure to harsh conditions, such as boiling:

#Question id: 2033

#Unit 4. Cell Communication and Cell Signaling

Initiator complement components

#Question id: 4320

#Unit 3. Fundamental Processes

Forms of the Ras protein found in tumors usually cause which of the following events to occur?