Protein Lab.  We soaked samples of egg white in test tubes of pepsin, hydrochloric acid and in a mixture of pepsin and hydrochloric acid, which we call gastric juice.  Our results supported our hypothesis that neither hydrochloric acid nor pepsin alone has a digestive effect on protein.  Gastric juices (a mixture of hydrochloric acid and pepsin) break proteins down into amino acids in the stomach.

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