Protein digestion/absorption and within the diet. Flashcards
Where does protein digestion occur?
NOT IN MOUTH
- Stomach
- Proteases and proenzymes
- Pepsin from pepsinogen - Small Intestine
Protein breakdown in stomach?
- Proteins are denatured by hydrochloric acid
- Pepsin begins digestion
- 10–20% of digestion
Where does Undigested protein go?
-Feces
Problems with digestion
- Celiac disease (Gluten from wheat, rye and barley)
2. Cystic fibrosis
Is pepsinagin active or inactive?
Inactive
Protein digestion in small intestine?
Proteases and intestinal lining cells
Where are Amino acids and peptide absorbed?
Small intestine
What are Pancreatic Proteases?*
Arginine + lysine+ Phenylalanine + Tyrosine
Specific to individual bonds. Made in pancreas- used in small intestine.
What is the first step of pepsin when digesting proteins?
- break down the chains of amino acids
- Trypsin breaks the bonds of arginine and lysine.
- Chymotrypsin breaks the bond of Phenylalanine and tyrosine.
Carboxpeptidase?*
Phenylalanine + Arginine+ Lysine+ tyrosine
ability to clean off/slip off the terminal Amino Acids
Dipeptidase?*
Arginine+ lysine+ phenylalanine
comes from small intestine
Tyrosine is connected to?*
Arginine
Chymotrypsin is connected?*
Phenylalanine
Protein synthesis
-Directed by cellular DNA
Amino Acid assembled in specific sequence
Draws on Amino Acid pool as needed
Synthesis of nonprotein molecules
Precursors:
- Neurotransmitters
- Vitamins (niacin (nonessential)
- DNA
- RNA
- melanin
- histamine
- glucose
Protein turnover?
Constant recycling of protein
Amino Acid Pool?
Available AA:
-Protein synthesis; produce energy and glucose
Protein and nitrogen excretion in the body?
Breakdown of amino acids:
- Removes nitrogen (amino) group
- Converts amino group to ammonia
- Ammonia to liver for conversion to urea
- Urea excretion via urine
Goes from liver ->urea -> excreted through urine.
Nitrogen balance
Nitrogen intake vs. nitrogen output
Nitrogen equilibrium
Nitrogen intake = nitrogen output
-Healthy grown adults
Positive nitrogen balance
Nitrogen intake > nitrogen output
Growth; recovery from illness
Negative nitrogen balance
Nitrogen input is less then Nitrogen Output
ACUTE Injury + Illness
T/F: During the acute phases of injury and illness you are in the first phases of negative nitrogen balance.
TRUE
T/F: During recovery you want to be in a Negative nitrogen balance.
FALSE a positive nitrogen balance
Recommended protein intake for adults?
0.8 gram per kilogram body weight
Recommended protein intake for infants?
1.5 grams per kilogram body weight
Physical Stress
Infection, burns, fevers, surgery, and intensive weight training
Recommended protein intake for elderly?
1.0 grams per kg body weight.
T/F: Consumption in the United States;
Generally protein intake > protein needs
TRUE
Complete Proteins?
Supply all indispensable amino acids
Animal proteins; soy proteins
Incomplete Proteins?
Missing one or more indispensable amino acids
Most plant proteins
Two incomplete proteins = one complete
Complimentary Proteins?
Beans and rice. Together they give you all of the indespensible AA.
Evaluating protein quality has to have what?
- Amino acid composition has to be there.
- Needs to be Digestible
- Protein Digestibility-Corrected Amino Acid Score (PDCAAS)
What is Protein Digestibility-Corrected Amino Acid Score (PDCAAS)?
- Looks at your proteins and what will actually be in your body and bloodstream
- This is Used to determine %DV
Protein and Amino Acid additives
Structure, texture, and taste of foods
Protein and Amino Acid supplements
Generally not needed
Risks unknown
*Most individuals don’t need protein supplements.
(RARE) Too many of these ill result in kidney failure. *
