Chapter 6: Proteins

 A nutrient made up of carbon, hydrogen, oxygen,and nitrogen.  Proteins are composed of Amino Acids linked together into a chain.  Although all amino acids have the same basic structure, the 4 th carbon bonding site distinguishes the amino acid.

 Figure 6-1: Amino group and Acid group  The Simplest Amino Acid: Glycine- only contains a hydrogen atom for the side group.  (Refer to Figure 6-2)  There are 20 common amino acids, 9 of which are essential. (What does this mean?)

 Condensation reactions link the amino acids.  Di-peptide Bond: 2amino acids bonded together  Tri-peptide bond: 3 amino acids linked together.  Poly-peptide bond: several amino acids linked together. Most of the proteins that make up your body are poly-peptide bonds,  For example Insulin (Refer to figure 6-4)

 Amino acids are linked together in different sequences to form different proteins in the body.  That is why there are so many different proteins.

 There are an estimated 30,000 different kinds of proteins.  Each human body is different because of the amino acids sequence that is determined by genetics.

 Deoxyribonucleic Acid (DNA) serves as a template for making strands of MRNA.  Messenger RNA carries a code which specifies the sequence of amino acids attaching together in a chain to form proteins.  MRNA attaches to a ribosome and presents its list, so the amino acids then line up in the proper order to form the correct protein.  Transfer RNA- is responsible for collecting the amino acids from the cell fluids and bringing them to the MRNA.

 The amino acids then line up in order, the enzymes bind them together to form a protein strand, and the strand is released.  There is a circumstance where there is an error in sequencing of the amino acids.  Valine is in the place of glutamic acid.  What is the form of anemia called?

 (Refer to Figure 6-8)  The red blood cells appear crescent in shape and interfere with oxygen transport and blood flow.

 Page 185  When glucose and fats are limited, the cells are forced to use amino acids for energy and glucose.  When the amino acids are broken down, they are first deaminated.  Deamination - stripping of the NH2 group  Nh2 group is converted into ammonia by the liver-----liver combines it with co2, which converts it to urea-----bloodstream--- to kidneys---filtered out in the urine.

 The body needs a great amount of water to aid the kidney in ridding itself of the urea.  Someone on a high protein diet must consume high amounts of water to dilute and help excrete the urea.  If you consume a high protein diet, and not enough water, you are risking dehydration.

 High quality proteins contain all essential amino acids and are referred to as ◦ Complete Protein Foods: all animal derivatives.  (meats, fish, poultry, eggs, dairy products) ◦ Incomplete Protein Foods: lack one or two amino acids: Vegetables, grains, nuts, seeds,and legumes.

 Two incomplete protein food sources that lack different amino acids and provide all essential amino acids  Vegetarians will eat proteins from different incomplete sources at some point during the day and receive all amino acids.  Refer to Handout

 Page 181.  1. Building and Repairing Body Tissues ◦ Protein forms the building blocks of the muscles, blood, and skin. ◦ Collagen is a protein substance that must be layed down for building bones and teeth, and it provides the material of ligaments and tendons. ◦ Protein helps to repair or replace damaged cells.  Ex- muscle tissues use protein to build larger muscles and stronger muscles after exercise.

 2. To make Enzymes-which facilitate chemical reactions. ◦ Chapter 3 focused on several digestive enzymes that break down the 3 energy nutrients. ◦ These enzymes are protein substances.

 3. Some Hormones are made of Protein- chemical messengers that send a message to facilitate a chemical reaction. ◦ Ex- Insulin regulates blood glucose  Thyroxin regulates metabolic rate  Calcitonin regulates blood calcium

 4. Fluid Balance -large proteins of the blood don’t normally cross through the walls of the blood vessels.  Protein is hydrophillic and attracts water, which helps to maintain osmotic pressure in the blood stream.  When someone is suffering from extreme malnutrition, the blood proteins will seep out of the blood vessels and into the tissues, resulting in edema.(because the water follows the protein into the tissues and causes the swelling).

 5. Acid-Base Balance-protein accepts or release hydrogen ions, thereby maintain acid/base balance of the body fluids.

 6. Transporters- Proteins are responsible for carrying nutrients and other substances throughout the body. ◦ Examples-  Lipoproteins: carries? __________  Hemoglobin: carries? ___________

 7. Antibodies-which defends the body against disease or foreign bodies. ◦ When the body detects an invading antigen, it produces antibodies which work quickly to fight off the antigen. Once the body has made the specific antigen it remembers to make them each time the body comes in contact with that antigen and immediately fights it off. ◦ Bonus Question- Identify a case where the body tries to fight off an antigen, when this is undesirable.

 8. Source of Energy and Glucose  9.Other Roles -Blood clotting (fibrin) and  Vision (opsin)

 Protein energy malnutrition- PEM  (Refer to Table 6-3)  Marasmus  Kwashiorker

 Heart Disease  Cancer  Bone Losses and Osteoporosis  Weight Control  Kidney Disease

.8 grams/Kg. of body weight  Athletes need about 1.2 to 1.7 grams/kg of body weight  For someone who weighs 195 lbs. and is an elite athlete, needing the greatest amount of protein, how much should he get daily?

 Protein Powders- When supplements may slightly increase protein synthesis but it does not enhance athletic performance  Amino Acid Supplements- large doses cause diarrhea.  An excess of one amino acid creates a demand for a carrier for other amino acids, possibly resulting in a deficiency of it.