1. Proteins: From Foods to Cells in the Body

2. Protein Denaturation to Digestion
Causes the protein to change shape or conformation but the protein and the amino acids are still intact.
Can be caused by heat, alkali or acid treatments, or metals.
Enables the protein can be digested
Example: cooking an egg; adding lemon to milk
Digestion
Protease enzymes secreted by pancreas and GI mucosal cells break the protein strand down releases the amino acids.
Amino acids are absorbed, transported to cells and used to build

3. Protein Synthesis
We eat protein, denature & digest the protein, absorb & transport the amino acids to the cells, then within each cell, protein is made (synthesized) according to the DNA.
Protein is synthesized in a process of converting DNA to RNA & then protein.
In transcription, the double-stranded DNA is copied into single-stranded mRNA(messenger RNA) by the enzyme RNA polymerase
Protein synthesis consists of a number of stages including: preparing tRNA molecules for use by the ribosome; attaching the ribosome molecule to the mRNA; and the translation of the mRNA information to the ribosome for protein formation.

4. Animation: https://www.youtube.com/watch?v=NJxobgkPEAo
Cytoplasm
Animation:

5. Protein Configuration
Protein character determined by:
How the 20 amino acids are combined together (the sequence).
The polypeptide strand folding & interacting
Configuration:
Primary - linear
Secondary helical or beta sheet formation.
Tertiary - 3 dimensional folding
Quaternary – more than one polypeptide chain
Ex: Hemoglobin
Ex: myoglobin
Enzyme:
Triose-phosphate isomerase

6. Functions of Body Proteins
Growth and maintenance replace, repair – skin, hair, bones, muscles, tendons, ligaments
Regulatory Roles
Body structures
Enzyme action
Hormones insulin & glucagon, secretin & cholecystokinin.
Antibodies, complement proteins, circulating components of immunity
Fluid (Albumin) and electrolyte balance
Acid-Base Balance (alkalosis, acidosis, buffers)
Transport Proteins
(sodium/potassium pump; lipoproteins)
Energy Production

7. Function of Protein in the Body7

8. Protein-Energy Malnutrition -PEM
Kwashiorkor –lack of protein
Produces edema (swelling of body tissues)
Maramus– lack of calories
The individual looks undernourished (skin & bones, starvation)
Dysentery
AIDS

9. Protein Excess Is most common in athletes & fad dieters.
Increases risk of:
Dehydration- body requires more water to flush protein waste from system (urea)
Liver & spleen enlargement.
Accelerated kidney aging.
Metabolic acidosis (with low carbohydrate intake)
Vitamin B6 deficiency, Ca & Zn loss.
Heart disease & cancer.
Body Builders sample diet analysis results
5500 calories
36% calories from protein, 49% carbohydrate, 15% fat
Inadequate in vitamin E and calcium

10. Adult Protein Need (DRI & AMDR) Sample Calculations
Eric weighs 90 Kg and ate 88 g of protein and 3000 Calories in one day.
What is his DRI for protein?
90 Kg x 0.8 gm/Kg = 72 gm protein
What % of his DRI for protein did he consume?
88 gm ÷ 72 gm x 100 = 122%
Intake high or low?
What % of calories in his diet came from protein?
88 g protein x 4 kcal/gm = 352 kcal from protein
352 kcal ÷ 3000 kcal x 100 = 11.7%
High, low, normal?