With respect to X-chromosome inactivation, which, if any, of the following statements are not correct? 

I. X-chromosome inactivation in mammals begins in the pre-implantation embryo 

II. In humans all diploid cells that carry two normal X-chromosomes are subject to a random pattern of X-inactivation. 

III. Once a decision has been made to inactivate an X chromosome (either the paternal or maternal X), all descendant cells show the same pattern of X-inactivation. 

IV. The inactivated X chromosome becomes a highly condensed Barr body in which genes are silenced across the length of the chromosome.

TLS Online TPP Program

#Question id: 2438

#Unit 2. Cellular Organization

Rac, a GTPase superfamily protein,

a. is related to Ras.                             

b. may be activated by growth factors.

c. stimulates lamellipodia formation. 

d. stimulates filopodia formation.

e. stimulates stress fiber assembly.

TLS Online TPP Program

#Question id: 1943

#Unit 4. Cell Communication and Cell Signaling

What is HLA-DR2 a risk factor for?

TLS Online TPP Program

#Question id: 4522

#Unit 3. Fundamental Processes

Gal4p contains a

TLS Online TPP Program

#Question id: 26387

#Unit 3. Fundamental Processes

ORC in S. cerevisiae, Schizosaccharomyces pombe, Drosophila, & Xenopus called respectively

TLS Online TPP Program

#Question id: 4433

#Unit 3. Fundamental Processes

Which cis sequence can function within an intron to regulate transcription?