Question

Which of the following is true about allosteric enyzmes? A) They typically catalyze the last reaction in a metabolic pathway since it is the critical step in the synthesis of the desired end product. B) They can have one subunit or several, depending on their catalytic needs. C) Their activity is often altered by a downstream product to form a feedback regulatory loop. D) They show a hyperbolic activity curve that increases with high levels of substrate. E) A and C The Michaelis-Menten model states that an enzyme catalyzes a chemical reaction by: A) converting products to substrates. B) speeding up the reaction by always operating at its maximal velocity. C) binding to the substrate to form an enzyme-substrate complex. D) overcoming competitive inhibition. E) becoming covalently modified through an acyl-enzyme intermediate.

Answer 1

9) Option E) is TRUE

Allosteric enzymes typically catalyze the last reactions within a metabolic pathway. Allosteric enzymes are regulatory enzymes. (Option ATRUE) Chemical signals in their activities are controlled by cell. Allosteric regulations are a natural example of control loops, such as feedback from downstream products or feedforward from upstream substrates. ((Option C is TRUE). They are made up of multiple subunits assembled into a single enzyme complex by noncovalent bonds and have more than one active site. They are made up of multiple subunits assembled into a single enzyme complex by noncovalent bonds, so Option B is FALSE. Conformational changes in the enzyme, giving sigmoidal kinetics rather than the hyperbolic kinetics of classical enzymes, so Option D is FALSE

10) Option C) is TRUE

The Michaels menten model states that an enzyme catalyzes a chemical reaction by binding to substrate to form enzyme substrate complex.

Michaelis–Menten proposed a mathematical model of the reaction. It involves an enzyme, E, binding to a substrate, S, to form a complex, ES, which in turn releases a product, P, regenerating the original enzyme. This may be represented as-

E + S ç==è ES <=> E + P