Chapter 6 Flashcards
What makes up the basic structure of a protein?
Composed of carbon, hydrogen, oxygen, and nitrogen
Arranged in strands of amino acids
What is the main determinant of a protein’s function?
The DNA (genetic sequence)
Specific structure/shape of proteins enables them to perform different tasks
What are the main functions of different proteins?
WORKING proteins: enzymes, antibodies, hormones, oxygen carriers, etc
STRUCTURAL proteins: tendons, ligaments, muscle fibres, found in bone, teeth, hair, nails
What does the stomach do for digesting proteins?
Gastric acid (HCl) denatures proteins, and pepsin cleaves some peptide bonds
What does the small intestine lumen do for digesting protein?
Pancreatic enzymes cleave polypeptides to di/tri peptides
What does the brush border membrane (SI) do for digesting proteins?
Enzymes cleave di/tri peptides to singe amino acids
Give 7 basic functions of proteins
Growth/maintenance
Hormones/enzymes
Immune function
Acid-Base balance
Fluid & electrolyte balance
Blood clotting
Energy
When are amino acids wasted?
Energy is lacking
Protein is over abundant
An AA is oversupplied (eg. supplement)
Diet has too few essential AAs
What is the daily recommended intake (DRI) for proteins?
0.8g per kg of body weight
males: ~56 g/day
females: ~46g/day
DRI min: 10% total energy
DRI max: 30% total energy
What 2 factors influence protein quality?
Digestibility (improved by moist heat)
-animal protein: >90% absorbed
-plant protein: 70-90% absorbed
Amino acid composition
What are complementary proteins?
2+ proteins whose AA structures supply the essential AAs missing from the other
What does “PDCAAS” stand for?
Protein Digestibility-Corrected Amino Acid Score
reflects protein digestibility and proportion of AAs provided
On the 0-100 scale of protein digestibility, what are some examples of what some foods might score?
Egg white, ground beef, chicken products, tuna = 100
Soybean = 94
Wheat = 25
How does a person’s size and stage of growth affect their nitrogen balance?
Equilibrium: normal healthy adult
Positive: child, pregnant woman
Negative: surgery patient, astronaut
What are the 2 types of protein malnutrition?
MARASMUS
-<2 years old
-total diet deficiency
-slow, chronic
-severe weight loss
KWASHIORKOR
-1-3 years old
-rapid onset, acute
-some weight loss & muscle wasting
-edema (swelling)
What are some consequences of excessive protein intake?
Associated with obesity
Increased sat. fats
Kidney & liver problems
Bone mineral loss
More Ca++ lost through urine
Is high protein intake a good or bad treatment for an existing kidney problem?
Bad, it will make it worse
The most effective way is the reduce the protein intake
