#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: 7139
#Unit 5. Developmental Biology
If apoptosis in the developing limb were blocked, what feature of a normal limb would not form?
#Question id: 4967
#Unit 11. Evolution and Behavior
Recent evidence indicates that the first major diversification of multicellular eukaryotes may have coincided in time with the
#Question id: 28311
#Unit 5. Developmental Biology
zona pellucida is made of glycoproteins, Which of the following zona pellucida or ZP protein is differentiating between mouse and human?
#Question id: 10482
#Unit 6. System Physiology – Plant
A herbicides dichlorophenyldimethylurea (DCMU) is known as diuron an inhibitor of photosynthetic electron transport. Which one of the following option would be correct about diuron?
a.) Blocks electron flow at the plastoquinone acceptors of PSII by competing for the binding site of plastoquinone
b.) causes a partial inhibition of stomatal closing
c.) accepts electrons from the early acceptors of PSI such as A0 and then reacts with oxygen to form superoxide, O2 –
d.) causes a partial inhibition of light-stimulated stomatal opening