Practice Questions

Low temperatures slow molecular motion without permanently altering enzyme structure. Normal activity usually returns when the temperature is restored to the optimum value.

As substrate becomes depleted, enzyme-substrate complex formation decreases, reducing the overall reaction rate.

Temperature and pH strongly influence enzyme activity. Keeping them constant allows the effect of the experimental variable to be measured accurately.

More enzyme molecules provide more active sites, allowing more substrate molecules to be converted into product per unit time.

The ionization state of amino acid residues determines substrate binding and catalytic efficiency. Changes in pH alter these charges.

Thermophilic enzymes are structurally adapted to function efficiently at temperatures that would denature most ordinary enzymes.

Enzymes from different organisms and tissues have different amino acid compositions and structures, resulting in different optimum temperatures.

At low substrate concentrations, many active sites remain free. Therefore, increasing substrate concentration proportionally increases enzyme-substrate complex formation.

At saturation, all enzyme molecules are engaged in enzyme-substrate complexes, so increasing substrate concentration no longer increases the reaction rate.

High temperatures disrupt hydrogen bonds and other weak interactions, causing loss of the enzyme's three-dimensional structure and decreasing catalytic activity.