Question

The human stomach is lined with glands that produce several chemicals that help in the process of digestion. One of these chemicals is hydrochloric acid, a powerful acid that makes the stomach very low in pH. Another substance is mucus--this substance lubricates and protects the stomach wall. A third substance is the enzyme pepsin which helps to break down protein molecules into smaller molecules called peptides.

If the chemical enzyme pepsin was mixed with some proteins in a test tube in a laboratory, which of these outcomes would you predict?
A) Pepsin would probably NOT break down proteins in the test tube because enzymes cannot exist outside of the human body.
B) Pepsin would partially break down the protein molecules but would not work well due to the absence of DNA in the test tube.
C) Pepsin would probably NOT break down proteins in the test tube because pepsin is designed to work at very acidic pH ranges.
D) Pepsin would break down the protein molecules equally well in the laboratory as in the human stomach since it is a stable chemical.

Answer 1

C) Pepsin would probably NOT break down proteins in the test tube because pepsin is designed to work at very acidic pH ranges.

Step-by-step explanation:

Pepsin is the main proteolytic enzyme active in gastric juice, an aqueous solution rich in hydrochloric acid and enzymes that act on protein digestion. Gastric juice leaves the stomach with very low pH levels, which means that the stomach becomes extremely acidic, an ideal environment for the work of enzymes that work on digestion, including pepsin. Pepsin is produced by the main stomach cells via zymogens and has the function of digesting proteins by catalyzing the hydrolysis of these molecules by breaking down the peptide bonds between some amino acids. The products of this breakdown are relatively long chains of amino acids, oligopeptides such as peptides and proteoses.

As stated earlier, pepsin works at very low pH conditions, ie in very acidic environment, so we can conclude that if pepsin were mixed with some proteins in a test tube, pepsin would probably not break down the proteins. in the test tube because pepsin is designed to work in very acidic pH ranges.

Answer 2

The right answer is C.

Pepsin (from Greek pepsis, meaning digestion, peptein = digest) is a digestive endoprotease of gastric juice.

Pepsin degrades food bolus proteins by hydrolysing peptide bonds before aromatic amino acids.

The optimum pH of action of pepsin is between 1.8 and 4.4.

It is mostly composed of aspartic acid and glutamic acid.