NutritionLesson 3 of 5 in the course Metabolism and Nutrition

Protein Digestion, Amino Acid Metabolism, and Related Disorders

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Proteins are essential building materials and working molecules throughout the body. To use dietary protein, the digestive system must break it into amino acids and small peptides that can be absorbed and used by cells.

Proteins serve many roles: they form structural materials such as collagen in bones and tendons, act as enzymes, carry oxygen in hemoglobin, and participate in cell signaling, transport, and muscle function. Protein is also needed for growth and tissue repair.

All flashcards

What are essential amino acids?
Amino acids the body cannot synthesize in sufficient amounts and must obtain from food.
How do stomach acid and pepsin contribute to protein digestion?
Hydrochloric acid denatures proteins; pepsin cuts them into shorter polypeptides and peptides.
How is trypsin activated in the small intestine?
Enterokinase converts inactive trypsinogen into active trypsin.
What is the role of the urea cycle?
It converts nitrogen from ammonium into urea, helping prevent toxic ammonium accumulation.
What metabolic conversion is impaired in pyruvate dehydrogenase complex deficiency?
The conversion of pyruvate into acetyl CoA is limited.

Quiz questions

  1. Which pancreatic response to secretin helps neutralize acidic chyme entering the small intestine?Answer: Increased release of sodium bicarbonate
  2. Where does the urea cycle occur primarily?Answer: In the liver
  3. What happens during transamination?Answer: An amino group transfers from an amino acid to a keto-group-containing molecule.
  4. Which conversion is directly catalyzed by the pyruvate dehydrogenase complex?Answer: Pyruvate to acetyl CoA
  5. Which enzyme deficiency causes phenylalanine to accumulate in phenylketonuria?Answer: Insufficient phenylalanine hydroxylase activity

Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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