#Question id: 5117
#Unit 5. Developmental Biology
The pathway from a gene to a protein in eukaryotic cells involves:
#Question id: 4104
#Unit 3. Fundamental Processes
Consider following statements for catalytic mechanism of RNA polymerase
A. RNA synthesis by RNA polymerase. The reaction involves two Mg2+ ions, coordinated to the phosphate groups of the incoming nucleoside triphosphates (NTPs)
B. Three Asp residues, which are highly conserved in the RNA polymerases of all species. One Mg2+ ion facilitates attack by the 39-hydroxyl group on the phosphate of the NTP; the other Mg2+ ion facilitates displacement of the pyrophosphate, and both metal ions stabilize the pentacovalent transition state.
C. About 17 bp of DNA are unwound at any given time. RNA polymerase and the transcription bubble move from left to right along the DNA as shown, facilitating RNA synthesis. Movement of an RNA polymerase along DNA tends to create negative supercoils (overwound DNA) ahead of the transcription bubble and positive supercoils (underwound DNA) behind it.
D. The RNA polymerase is in close contact with the DNA ahead of the transcription bubble as well as with the separated DNA strands and the RNA within and immediately behind the bubble. A channel in the protein funnels new NTPs to the polymerase active site. The polymerase footprint encompasses about 35 bp of DNA during elongation.
#Question id: 6981
#Unit 5. Developmental Biology
Hedgehog signaling at the compartment boundary in the Drosophila wing disc leads to the expression of what signaling molecule in the adjacent anterior cells?
#Question id: 7220
#Unit 5. Developmental Biology
The anterior-posterior polarity of the drosophila embryo is established while the oocyte is still in the egg chamber, and it involves interactions between the developing egg cell and the follicular cells that enclose it. Following are certain statements:
A. The gurken message appears to be synthesized in the oocyte, and it is transported into the nurse cells. Here it becomes localized between the nucleus of nurse cells and the cell membrane, and it is translated into Gurken protein.
B. Gurken signal is received by the follicle cells at that position through a receptor protein encoded by the torpedo gene.
C. This signal results in the “posterior -anteriorization” of these follicle cells.
D. Posterior follicle cells signals to recruit Par-1 protein organizes microtubules specifically with their minus (cap) and plus (growing) ends at the anterior and posterior ends of the oocyte, respectively.
E. The motor protein kinesin, is an ATPase that will use the energy of ATP to transport material to the plus end of the microtubule. Dynein, however, is a “minus-directed” motor protein that transports its cargo in opposite direction.
F. These zygotic messengers bicoid and nanos mRNAs are carried by motor proteins along the microtubules to the anterior and posterior ends of the oocyte, respectively.
Which combination of the above statements are correct?
#Question id: 19163
#Unit 13. Methods in Biology