Draw the chemical mechanism (with electron-pushing arrows) for the addition of an RNA nucleotide triphosphate to a growing mRNA transcript. Be sure to explicitly show the attacking nucleophile and the leaving group.

Eukaryotes modify mRNA with an m7G cap: an  N7-methylated guanosine linked via a 5′ to 5′ triphosphate linkage, and by methylation at the 2'-hydroxyl of the penultimate nucleoside. What cofactors involved in the capping reaction? Show their structure and properties

Human ribonucleotide reductase has two allosteric sites, the S site and the A site. What is the function of each? How does this compare with the E. Coli enzyme discussed in the text?

Draw the mechanism of action of an HIV protease. Label the substrate, the intermediates, and the products. Indicate each type of catalysis that occurs throughout the mechanism..

Give only typing answer with explanation and conclusion

Consider the mechanism of the enzyme RNase:   What would happen to the Km (i.e., would it increase, decrease, or stay the same) if the his12 was mutated to a lysine? Explain.   What would happen to the Kcat (i.e., would it increase, decrease, or stay the same) if the his12 was mutated to a valine? Explain.

The biosynthetic pathway for the two amino acides E and H is shown schematically in the Figure below: A W E 2 Z H How would this pathway change if C was mutated and non-functional?

RNAi (or RNA interference) is the process of creating double-stranded RNA in the cells. Explain how  this strategy can be effective against COVID19 and describe how you would go about doing this generally.

A number of mutations affect the expression of the lac operon in E. coli. The genotypes of several E. coli strains are shown below. ("+" indicates a wild-type gene with normal function and "-" indicates a loss-of-function allele.) Please predict which of the following strains would have the lowest beta-galactosidase enzyme activity, when grown in the lactose medium. Orpt o* z* r* Orpt ot z* Y OrptoztY Orrotzr OrPotz*Y

The intermediates A, B, C, D, E, and F all occur in the same biochemical pathway G is the product of the pathway, and mutations 1 through 7 are all G –, meaning that they cannot produce substance G. The following table shows which intermediates will promote growth in each of the mutants. Arrange the intermediates in order of their occurrence in the pathway at which each mutant strain is blocked. A “+” in the table indicates that the strain will grow if given that substance, an “o” means lack of growth.