Chapter 6 – Protein: Amino Acids
Describe how the chemical structure of proteins differs from the structures of carbohydrates and fats?
-The nitrogen atoms give the name amino (nitrogen containing) to the structures of carbohydrates and fats.
Explain the process used by the body to synthesize new proteins.
-More than half of the amino acids are nonessential, meaning the body can synthesize them for itself. Proteins in foods usually deliver these amino acids, but it is not essential that they do so. Each human being is unique because of small differences in the body’s proteins. These differences are determined by genes. The instructions for making every protein in a person’s body are transmitted by way of the genetic information received at conception.
List the 8 major functions of proteins
-Growth and maintenance
Building blocks for most body structures (collagen)
Replacement of dead or damaged cells
-Enzymes
Break down, build up, and transform substances
Catalysts – assist with quicker, more efficient reactions
-Hormones
Messenger molecules
Transported in blood to target tissues
-Regulators of fluid balance
Edema-swelling due to excess fluid
-Acid (base regulators)
Maintain balance between acid and base within body fluids
-Transporters
Carry lipids, vitamins, minerals
-Antibodies
Defend body against disease
Specificity- Immunity – memory works quicker the second time exposure occurs
-Energy and Glucose
Starvation and insufficient carbohydrate intake
Body can break down protein to make AA available for energy (glucose).
Describe nitrogen balance and provide examples of positive nitrogen balance, negative nitrogen balance, and equilibrium.
-In healthy adults, protein synthesis balances with degradation, and protein intake from food balances with nitrogen excretion in the urine, feces, and sweat. When nitrogen intake equals nitrogen output, the person is in nitrogen equilibrium, or zero nitrogen balance. If the body synthesizes more than it degrades, then the protein added and nitrogen status becomes positive. If the body degrades more than it synthesizes, the protein is being lost and nitrogen status becomes negative.
Describe denomination, where it occurs in the body, the produce and fate of these products.
-When amino acids are broken down (as occurs when they are used for energy or to make glucose or fat), they are first delaminated – stripped of their nitrogen – containing amino groups. Two products result from denomination: one is ammonia; the other product is the carbon structure without its amino group – often keto acid. Ammonia – released in blood stream, converted to urea by the liver, and filtered by the kidneys. Keto acid – used for energy, used to produce glucose, fat.
Discuss the factors used to evaluate protein quality.
-Two factors in protein quality are digestibility and amino acid compositions. Protein digestibility depends on such factors as the protein’s source and the other foods eaten with it. The digestibility of most animal
