Objectives
• Discuss at least four functions of protein in the body
• Distinguish between essential and nonessential amino acids
• Describe the primary steps in protein synthesis and what determines the sh
a protein
• Explain how denaturation may alter protein function
• Summarize protein digestion and absorption
• Identify the Recommended Dietary Allowances and Acceptable Macronutrie
Distribution Ranges of protein for adults
• Explain protein turnover and how amino acids may be used for energy
• Explain the concept of nitrogen balance and the factors required to retain le
body mass
• Identify at least three sources of protein in the U.S. diet and factors to consi
choosing protein foods
• Describe protein deficiency diseases and identify regions in the world where
condition is prevalent
Protein is an essential, energy-yielding macronutrient
Macronutrients
• Include protein, carbohydrates, fats and water
• are essential nutrients that must be supplied through the diet
• Are needed in large amounts compared to the micronutrients (vitamins and
minerals)
, • With the exception of water, all macronutrients supply energy (calories)
Protein, carbohydrates, and fats are composed of carbon, hydrogen, and oxygen. Protein
contains nitrogen
Why do we Need Protein?
Protein has many critical roles in the body:
Protein has many critical roles in the body
Structural material
• Muscle
• Bone
• Hair
• Skin
, • Fingernails
Growth, maintenance and repair
Energy source
Other critical functions
• Enzymes
• Hormones
• Antibodies
• Fluid balance
• pH balance
• Transporters
• Blood clotting
In order for proteins to work
they must have the right 3-D shape
It all starts by assembling the right protein building blocks in the right configuration
• These protein building blocks are known as amino acids
All amino acids have the same structure which includes:
• a central carbon atom (C)
• an amino group (-NH2)
• a carboxylic acid group (-COOH)
• a unique side chain
The unique side chain determines WHICH amino acid we are talking about
• there are 20 different side chains for 20 different amino acids