In goats, a beard is produced by an autosomal allele that is dominant in males and recessive in females. We’ll use the symbol Bb for the beard allele and B for the beardless allele. Another independently assorting autosomal allele that produces a black coat (W) is dominant over the allele for white coat (w). A cross allowed between BBbWw (male) X BBbWw (female). What is proportional of female progeny will beard with black coat?

#Question id: 1239

#Unit 4. Cell Communication and Cell Signaling

GTPases serve in many signal transduction pathways and the presence of GTP or GDP dictates whether the pathway is on or off, respectively. Which of the following statements is TRUE regarding guanine nucleotide exchange factors (GEF) and the role in these signaling pathways?

#Question id: 1238

#Unit 4. Cell Communication and Cell Signaling

Which of the following can lead to loss-of-heterozygosity in a tumor-suppressor gene?

a. deletion of the normal copy                       

b. non dysjunction during mitosis

c. somatic mutation of the normal copy

d. mitotic recombination between a wild-type and mutant allele

#Question id: 1237

#Unit 4. Cell Communication and Cell Signaling

Arrange the following events in the proper order in which they occur during transduction of the Notch/Delta signaling pathway:

a. cleavage of Notch by TACE                                  

b. binding of Delta to Notch

c. translocation of Notch segment to the nucleus      

d. interaction of Notch with transcription factors     

e. cleavage of Notch by Presenilin 1  

#Question id: 1236

#Unit 4. Cell Communication and Cell Signaling

Arrange the following events in the proper order in which they occur during transduction of the TNF-α signal

a. phosphorylation of I-κB                 

b. binding of E3 ubiquitin ligase to I-κB       

c. polyubiquitination of I-κB             

d. nuclear localization of NF-κB       

e. activation of TAK1 kinase

#Question id: 1235

#Unit 4. Cell Communication and Cell Signaling

Arrange the following events in the proper order in which they occur during transduction of the EGF signal:

a. transphosphorylation of the EGF receptor

b. dissociation of GDP from Ras                   

c. dissociation of Ras from Sos         

d. binding of GRB2 to the EGF receptor      

e. binding of GTP to Ras  

#Question id: 1234

#Unit 4. Cell Communication and Cell Signaling

Which of the following mutations would likely have a similar cancer-promoting effect as the RasD mutation?

a. mutation in Grb2 so that it cannot bind Sos

b. mutation in Sos so that it binds Ras independent of Grb2

c. mutation in GAP so that it cannot bind Ras

d. mutation in EGF receptor so that it binds GRB2 independent of EGF