NUT Week 4 Flashcards
What are the structural units of proteins?
amino acids
What differentiates amino acids from fats and carbohydrates?
the presence of nitrogen
how many different amino acids exist based on R groups?
20
What does it mean that amino acids are amphoteric?
they can carry a positive or negative charge depending on the pH of the solution
How do labile protein reserves differ from fat reserves?
labile protein reserves are limited and easily broken down for immediate needs, whereas fat reserves are more substantial
what percentage of total body protein is labile protein?
approximately 1%
what happens if protein intake is insufficient for an extended period?
skeletal muscle is broken down to provide amino acids
what accelerates protein catabolism?
critical illness, infections, caloric restriction, starvation, extensive burns, and surgery
What does nitrogen balance refer to?
the total nitrogen in the body, including protein nitrogen, urea, uric acid, and ammonia
how is nitrogen lost from the body
through urine, feces, sweat, and shedding of skin and gastrointentinal tract cells
what is negative nitrogen balance?
when body nitrogen loss exceeds intake
what does positive nitrogen balance occur?
during growth, pregnancy, and strength training
what is nitrogen equilibrium?
when nitrogen intake and loss are approximately equal in healthy individuals
name the 9 essential amino acids
- histidine
- isoleucine
- leucine
- lysine
- methionine
- phenylalanine
- threonine
- tryptophan
- valine
name 6 contionally essential amino acids
- arginine
- cysteine
- glutamine
- glycine
- proline
- tyrosine
Name 5 nonessential amino acids
- alanine
- aspartic acid (aspartate)
- asparagine
- glutamic acid (glutamate)
- serine
what determines protein quality?
The ability to provide essential and conditionally essential amino acids and digestibility
what must happen for amino acids to be absorbed?
they must be liberated from their protein structure
what is a complete protein?
a food source that provides all essential amino acids
name some complete protein sources
eggs, milk, cheese, meat, poultry, fish, tofu
what is an incomplete protein?
a protein that lacks or has too little of one or more essential amino acids
How can incomplete proteins be combined to form a complete protein?
By pairing foods with complementary amino acid profiles, like rice (high in methionine, low in lysine) and beans (high in lysine, low in methionine)
