Question

Enzymes, such as the one shown in the picture, work by fitting onto the substrate molecule like a lock-and-key action. Which statement is true, with regard to the enzyme and the substrate? A) The enzyme weakens chemical bonds in the substrate and catalyzes a change into the product. The enzyme itself remains unchanged. B) The enzyme weakens chemical bonds in the substrate and catalyzes a change into the product. The enzyme is also consumed in the reaction. C) The substrate reacts with the enzyme in the active site to produce a product. The enzyme, though changed, does not become a part of the product. Eliminate D) The substrate reacts with the enzyme in the active site to produce a product. Both the enzyme and the substrate combine and change into a product.

Answer 1

A) The enzyme weakens chemical bonds in the substrate and catalyzes a change into the product. The enzyme itself remains unchanged. 

Answer 2

The right answer is A) The enzyme weakens chemical bonds... The enzyme itself remains unchanged

The enzymes accelerate (catalyze) millions of times the chemical reactions. There are  numerous specific enzymes that play a role in physiological processes.

However, enzymes can be classified into six categories according to the biochemical reaction they perform:

*oxidoreductases, which catalyze redox reactions (such as peroxidase);

*transferases, which transfer a functional group from one molecule to another (such as methyltransferases that transfer a methyl group);

*hydrolases, which hydrolyze chemical bonds (such as nucleases that cut DNA or RNA);

*lyases, which break bonds but produce new ones simultaneously (such as the adenylate cyclase that produces cyclic AMP from ATP);

*isomerases, which rearrange the functional groups of a molecule to form isomers (such as topoisomerases that roll up DNA);

*ligases or synthetases, which allow the joining of two molecules (such as DNA ligases).

Only substrates and products vary from one enzyme to another.

Their cell concentration is always extremely low, of the order of 10-7 to 10-9 mol / l; indeed, as for any catalyst, the enzyme is not consumed during the reaction that it catalyzes.