Metabolic pathways frequently contain reactions with positive standard free-energy values, yet the reactions still take place. How is this possible?

Consider the following chemical equation whose delta(G) = 9kcal/mol: AC + BD ---> AB + CD    what are the reactants and what are the products  is this reaction spontaneous? How do you know?  Is energy released or consumed by this reaction?  If an enzyme, which catalyzes this reaction is added, what will happen to delta (G) If this reaction is coupled to another reaction, whose delta(G) is -12 kcal/mol, what will be the net delta(G) value? will the overall reaction be spontaneous

The protein catalase is an enzyme that catalyzes the decomposition of hydrogen peroxide:2 H2O2 (aq) → 2 H2O (l) + O2 (g)and has a Michaelis-Menten constant of 25 × 10-3 mol·dm-3 and a turnover number of 4.0×107s-1.The total enzyme concentration is 0.016×10-6 mol·dm-3 and the initial substrate concentration is4.32×10-6 mol·dm-3 Calculate the maximum reaction rate (????) for this enzyme, and the initial rateof this reaction. Note that catalase has a single active site.

For each pair of biomolecules, identify the type of reaction (oxidation‑reduction, hydrolysis, isomerization, group transfer, or internal rearrangement) required to convert the first molecule to the second. In each case, indicate the general type of enzyme and cofactor(s) or reactants required, and any other products that would result. A(n) (hydrolysis, oxidation reduction, group transfer, isomerization, internal rearrangment) reaction converts glucose to fructose. This reaction is catalyzed by a(n) (dehydrogenase, isomerase, kinase, phosphatase).