Proteins: From Foods to Cells in the Body

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

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.

Animation: https://www.youtube.com/watch?v=NJxobgkPEAo Cytoplasm http://image.slidesharecdn.com/protein-synthesis-1211978288012505-9/95/protein-synthesis-1-728.jpg?cb=1211952941 Animation: https://www.youtube.com/watch?v=NJxobgkPEAo

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 http://cnx.org/resources/fb4997cac700d686322c9930cf9abc5cfa187982/Figure_03_04_09.jpg

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

Function of Protein in the Body 7

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

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. http://www.learn-bodybuilding.com/images/bb/levron11.jpg Body Builders sample diet analysis results 5500 calories 36% calories from protein, 49% carbohydrate, 15% fat Inadequate in vitamin E and calcium

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?