Chapter 32, Problem 1MC

Which of the following statements is False?

a. Overheating to 108˚F is likely to disrupt covalent bonds in enzymes.

b. Overly acidic conditions can disrupt protein structure.

c. Low body temperature will reduce the rate at which enzymes catalyze reactions.

d. Considerable metabolic activity is required to maintain a relatively constant environment.

Summary Introduction

Introduction:

The catalysts that promote the reaction to proceed in a biological environment are called as catalysts. Catalysts are used for accelerating the rate of a biological reaction, in fact, all molecular reaction within an organism need enzymes for its catalysis. Enzymes are said to catalyze in more than 5000 biological reactions. Most of the enzymes are proteins in nature; they increase the rate of reaction by decreasing the activation energy. There are total of six classes of enzymes based on their mechanism

Answer to Problem 1MC

Correct answer:

Covalent bonds in enzymes are stable at $\text{108°F}$ so there is no breakage of covalent bonds at $\text{108°F}$ Therefore Option (a) is the correct answer

Option (a) is given as “Overheating to $\text{108°F}$ is likely to disrupt covalent bonds in enzymes”.

Explanation of Solution

Justify reason for the correct statement:

The rate of enzymatic reaction increases with the increase in temperature. For every $\text{10°C}$ rise in temperature the rate of reaction goes up by $\text{50}\text{to}\text{100\%}$, this rate of reaction increases up to $1\text{00°F}$. Further increase in temperature leads to denaturing of the enzyme. But covalent bonds in the enzymes are the strongest bonds and have the capacity to withstand high-temperature changes and are important in maintaining the structure of the protein. Other bonds like Vander-wall forces, hydrogen bonds, and ionic bonds are comparatively weaker than the covalent bonds. Hence they break much before, then the enzyme does, making the enzyme non-functional.

Hence, option (a) is correct.

Justify reasons for the incorrect statements:

Option (b) is given as “Overly acidic conditions can disrupt protein conditions”.

The $\text{pH}$ also plays an important role in the activity of the enzyme. Higher acidic conditions have an effect on the state of ionization of the acidic and basic amino acid residues present in the protein leading to alteration of the protein structure hence making the enzyme nonfunctional. Since the given statement is true Hence, it is a wrong answer.

Option (c) is given as “low body temperature will reduce the rate at which enzymes catalyze reactions”.

The optimum temperature for the activity of enzymes is around $\text{37°C}$ decreases in temperature by $\text{10°C}$ lowers the activity of the enzyme by $\text{50}\text{-}\text{100\%}$. Since the given statement is true Hence, it is a wrong answer.

Option (d) is given as “Considerable metabolic activity is required to maintain a constant environment”.

Metabolic activity generates heat that is required to increase the temperature of the surrounding making it optimum for its activity. Since the statement is true Hence, it is a wrong answer.

Hence, options (b), (c), and (d) are incorrect.

Conclusion

Enzymes are made up of proteins and proteins are made from a specialized arrangement of amino acids. There are various bonds responsible for structural integrity of the protein such as hydrogen bond, ionic bond, bonds formed from the weak Vander-wall force and covalent bond. Some bonds are stable only for a narrow range in conditions such as temperature, $\text{pH}$, solubility and many more and any fluctuation in these conditions results in breakage of these bonds resulting in denaturation of the enzyme.