All of the following are true of enzyme-catalyzed reactions EXCEPT:A.the presence or absence of a post-translational modification may alter the activation energy Ea of the reaction.B.the enzyme does not affect the net reaction rate if the ratio of products to reactants equals Keq for the reaction.C.substrates can covalently modify the enzyme to cause a permanent decrease in the enzyme's turnover number kcat.D.the saturation of enzyme active sites by substrate molecules limits the maximum reaction velocity Vmax.Submit

Which of the following statements is/are true of enzyme catalysts?Group of answer choicesThey bind to substrates but are never covalently attached to substrate or product.They increase the equilibrium constant for a reaction, thus favoring product formation.They increase the rate at which substrate is converted into product.They lower the activation energy for the conversion of substrate to product.To be effective, they must be present at the same concentration as their substrates.

How do enzymes affect the rate of reactions?Enzymes decrease the rate of reaction via the binding of substrates to the enzyme active site.Enzymes increase the rate of reaction without being used up. This is achieved by the binding of substrate to the enzyme active site, where the reaction is catalysed.Enzymes decrease the rate of reaction via the binding of substrates to the enzyme active sites. Enzymes act as reactants.Enzymes increase the rate of reaction via the binding of substrates to the enzyme active sites. Enzymes act as reactants.I DON'T KNOWSUBMIT ANSWER

Enzymes are able to speed up a reaction by lowering the activation energy:Question 59 Answer Choices   A.  only if the reaction is exergonic.   B.  only if the reaction is endergonic.   C.  if the reaction is endergonic or exergonic   D.  if ΔG is positive.

Enzyme A catalyzes the conversion of substrate S to product P.  When enzyme A is phosphorylated, its kcat value changes from 10 s−1 to 5 s−1 and its KM value changes from 100 μM to 20 μM.  If equal concentrations of each enzyme form are used then compared to the unphosphorylated enzyme A, the phosphorylated form:A.has a higher catalytic efficiency and yields a faster reaction rate when [S] < 20 μM.B.has a higher turnover number and yields a faster reaction rate under saturating conditions.C.has a lower affinity for S and yields a slower reaction rate at all [S].D.is allosterically inhibited and yields a lower reaction rate at all [S].

Enzymes are catalysts that affect biological reactions. How do enzymes change the rates of reactions in the body?A.Enzymes decrease reaction rates by decreasing the energy of the products.B.Enzymes decrease reaction rates by lowering the activation energy.C.Enzymes increase reaction rates by lowering the activation energy.D.Enzymes increase reaction rates by increasing the energy of the reactants.