Metal ions such as Zn^2+ and Fe^3+ are often needed by enzymes as A) allosteres.
ID: 507161 • Letter: M
Question
Metal ions such as Zn^2+ and Fe^3+ are often needed by enzymes as A) allosteres. B) inhibitors. C) cofactors. D) substrates. E) isozymes. 24) 'Physiological conditions' for reactions within the body are approximately A) pH 3 and 37 degree C. B) pH 7 and 273 K. C) pH 7 and 37 degree C. D) pH 8 and 273 degree C. E) pH 7 and 37 degree F. A noncompetitive inhibitor A) alters the three dimensional structure of the enzyme. B) increases the rate of the enzyme-catalyzed reaction. C) binds at the active site of the enzyme. D) has its effect reversed by adding more substrate. E) has a structure similar to the substrate. The purpose of the many chemical reactions in our bodies is to A) produce the essential amino acids. B) produce the essential lipids. C) store chemical energy in the body for future use. D) release chemical energy for the production of macromolecules. E) All of the above. The general function of an enzyme in the body is to A) maintain homeostasis. B) catalyze chemical reactions. C) act as a reactant in carbohydrate storage. D) maintain a neutral pH. E) eliminate waste products from the blood. When an end product from an enzyme- mediate sequence is also an inhibitor for an earlier step in the reaction sequence, the process is referred to as A) competitive inhibition. B) concentration control. C) negative catalysis. D) irreversible inhibition. E) feedback control.Explanation / Answer
Solution
23. The limited activity of urease enzyme is called absolute specificity.
Absolute specificity - the enzyme will catalyze only one reaction.
24. Some enzymes works in the presence of other chemicals which serve as helper known as cofactors.
The cofactors are metal ions such as zinc (Zn2+), iron (Fe2+, Fe3+), magnesium (Mg2+) and copper (Cu2+). The metal ions may help to bind the enzyme and substrate together or it may serve as the catalytic centre of enzyme itself.
25. The physiological conditions for the reactions within the body are:-
pH 7 and 37°C
26. A non-competitive inhibitor binds to a site other than where the substrate binds and alters the three dimensional structure of the enzyme results reduces the catalytic efficiency of the enzyme so that Vmax is reduced. The substrate still binds with its usual affinity and hence Km remains the same.
27. The purpose of many reactions in our body is
a. Produce the essential amino acids
b. Produce the essential lipids
c. Store chemical energy in our body for future use
d. Release chemical energy for production of macromolecules
28. The tight control of enzyme activity is essential for homeostasis,
29. If an enzyme produces too much of one substance in the organism, that substance may act as an inhibitor for the enzyme at the beginning of the pathway that produces it, causing production of the substance to slow down or stop when there is sufficient amount is known as feedback inhibition.