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: 10304

#Unit 6. System Physiology – Plant

Pyruvate is coverted into the Acetyl-CoA, Acetyl-CoA contain the acetyl group which are comes from the pyruvate and Coenzyme A (CoA) that contain other groups such as;

a) A reactive thiol (—SH) group that is critical to the role of CoA as an acyl carrier in a number of metabolic reactions

b) contain pantothenic acid,  A hydroxyl group of pantothenic acid is joined to a modified ADP moiety by a phosphate ester bond

c) pantothenic acid carboxyl group is attached to β-mercaptoethylamine in amide linkage

d) Hydroxyl group at the 3’ position of the ADP moiety has a phosphoryl group not present in free ADP

which of the following correct observation about Coenzyme A (CoA)?

#Question id: 10305

#Unit 6. System Physiology – Plant

Pyruvate dehydrogenase complex Consists of three Distinct enzymes and it requires Coenzymes, these are;

#Question id: 10306

#Unit 1. Molecules and their Interaction Relevant to Biology

pyruvate dehydrogenase (PDH) complex requires five different coenzymes or prosthetic groups and these enzymesalso require four different vitamins in human nutrition are vital components of this system:

#Question id: 10306

#Unit 6. System Physiology – Plant

pyruvate dehydrogenase (PDH) complex requires five different coenzymes or prosthetic groups and these enzymesalso require four different vitamins in human nutrition are vital components of this system:

#Question id: 10307

#Unit 6. System Physiology – Plant

pyruvate dehydrogenase (PDH) complex requires many enzymes for their functions, which of the following enzyme are not the part of this complex?

#Question id: 10308

#Unit 1. Molecules and their Interaction Relevant to Biology

Oxidative decarboxylation of pyruvate to acetyl-CoA by the PDH complex, how the pyruvate dehydrogenase complex carries out the five consecutive reactions in the decarboxylation and dehydrogenation of pyruvate?

 A) Pyruvate reacts with the bound thiamine pyrophosphate (TPP) of pyruvate dehydrogenase, undergoing decarboxylation to the hydroxyethyl derivative

 B) A transesterification in which the —SH group of CoA replaces the —SH group of E2 to yield acetyl-CoA and the fully reduced (dithiol) form of the lipoyl group

 C) The reduced FADH2 of E3 transfers a hydride ion to NAD1 , forming NADH, the enzyme complex is now ready for another catalytic cycle

 D) The transfer of two electrons and the acetyl group from TPP to the oxidized form of the lipoyllysyl group of the core enzyme, dihydrolipoyl transacetylase, to form the acetyl thioester of the reduced lipoyl group

 E) Dihydrolipoyl dehydrogenase promotes transfer of two hydrogen atoms from the reduced lipoyl groups of E2 to the FAD prosthetic group of E3 , restoring the oxidized form of the lipoyllysyl group of E2

 Find out the correct sequence of action of this complex enzyme?