In the first step of aminoacyl group linkage to a tRNA, an amino acid reacts with ATP to yield an aminoacyl-AMP and pyrophosphate. The bond between the amino acyl group and the AMP is described as a mixed anhydride. Explain the differences between an anhydride bond and a mixed anhydride bond. Why is this reaction irreversible?

An enzymatic assay was performed using the enzyme phophofructokinase-1, which catalyses the committed step of the glycolysis pathway. What is the final concentration of the fructose 6-phosphate substrate in a test tube containing the following: 250 µL of 150pM fructose 6-phophate, 100 µL 20 mg.ml-1 phosphofructoskinase-1 and 150 µL 100mM buffer pH 7.5

Select the nonprotein nitrogen compounds from the listed analytes.   Question 57 options:   albumin   bilirubin   creatinine   ammonia   glucose   creatine kinase   uric acid   aspartate aminotransferase   lactate dehydrogenase   urea

Explain why site-directed mutagenesis of aspartate to asparagine in the active site of trypsin decreases the catalytic 10,000-fold.