#Question id: 2323
#Unit 2. Cellular Organization
Prior to replication the DNA in the nucleus is in the form of a tangled mass called
#Question id: 2002
#Unit 4. Cell Communication and Cell Signaling
What accounts for antibody switching (i.e., the switch of one B cell from producing one class of antibody to another antibody class that is responsive to the same antigen)?
#Question id: 7110
#Unit 5. Developmental Biology
What may be the molecular trigger that causes cells in the presomitic mesoderm to finally condense into somites?
#Question id: 7187
#Unit 5. Developmental Biology
Following statements regarding to feedback loops during limb development.
A. When the limb bud is relatively small, an initial positive feedback loop is established between Fgf10 produced in the mesoderm and Fgf8 produced in the ectoderm, promoting limb outgrowth.
B. As the limb bud grows, the ZPA is established, and another regulatory loop is created by inhibiting the BMP in mesoderm and maintain FGF expression.
C. In anterior region of the limb bud, Fgf8 positively regulates Etv4/5, which in turn repress Shh in this region, further reinforcing the posterior-to-anterior gradient of Shh from the ZPA.
D. In posterior region of the limb bud, Fgf8 positively regulates Etv4/5, which in turn repress Shh in this region, further reinforcing the posterior-to-anterior gradient of Shh from the ZPA.
Which of the following combinations are incorrect?
#Question id: 34105
#Unit 2. Cellular Organization