NSC 170C1 1st Edition Lecture 12 Outline of Last Lecture I Cardiovascular Disease Current Lecture Outline I What is protein A Amino Acids II Protein Functions Current Lecture I II III IV What is protein A The building blocks proteins are amino acids B Essential amino Acids i Amino acids are like digits in a phone numberthey link together to create an unique sequence ii Contain carbon hydrogen and nitrogen iii A unique side chain gives the amino acid its distinguishing qualities iv There are 20 amino acids Essential and nonessential amino acids A There are nine essential amino acids i The body cannot create these ii They must be obtained from foods iii Found in foods such as milk and meat B The remaining 11 nonessential amino acids i They can be created in the body so they are not essential in our diet Building protein from amino acids A Amino acids are joined together by peptide bonds B Dipeptide two amino acids C Tripeptide three amino acids D Polypeptide many E Proteins typically consist of 100 to 1 000 amino acids in a specific sequence Protein Function is altered by denaturation A Denaturation the alternation of a protein s shape die to exposure to heat acids or salts V VI VII B Does not alter the sequence of amino acids C Alters its function sometimes permanently i I E frying eggs marinating chicken acidic stomach juices What happens to protein you eat A Protein digestion begins in the stomach B stomach acid denatures protein strands C In the small intestine i polypeptides are broken down into tripeptides and dipeptides ii these are absorbs by intestinal cells and broken down into single amino acids iii Amino acids enter the body and travel to the liver iv The liver uses the amino acids according to your body s needs D The diet provides essential and nonessential amino acids E A limited amount of all these are stockpiled in amino acids pools in the blood and cells F The body constantly degrades its proteins to replenish the amino acids pools and build the new proteins it needs Protein Turnover A The process of continually degrading and synthesizing protein within the body i 200 grams of protein are turned over daily ii The intestines and liver account for as much as 50 percent of turnover B Protein and amino acids are lost daily through sloughed off skin hair nails and intestinal cells C Amino acids pools provide the building materials to synthesize replacement proteins and non protein substances such as thyroid hormones and melanin D Your body degrades and synthesizes proteins E When amino acids are broken down the components parts meet different fats i The nitrogen forms ammonia which is converted to urea by the liver and excreted in urine via the kidneys ii The carbon containing remnants are converted to glucose and used as energy or stored as fat F Surplus amino acids from excess dietary protein can t be stored as protein so they are stored as fat Proteins provide structural and mechanical support A Fibrous proteins in your bones muscles and other tissues help hold your body B Collagen i VIII IX The most abundant protein in your body and is found in all your connective tissues C Other proteins provide mechanical support by helping your muscles contract D Eating extra protein won t make muscles larger but weightbearing exercise will Proteins help maintain body tissues A Daily wear and tear on the body causes breakdown of hundreds of grams of protein each day B Proteins help create a new layer of outer skin every 25 to 45 days C Your body has trillions of red blood cells with life spans of just 120 days D The cells lining the inner surface of your organs such as lungs and intestines are constantly sloughed off excreted and replaced Proteins Build Enzymes and Hormones A Enzymes are substances that speed up reactions in the body i Many are proteins ii Are not changed damaged or used up in the process iii Many reactions also utilize a coenzyme such as a vitamin to initiate the reaction B Hormones are protein or lipid based chemical messengers that initiate or direct a specific action C Released from tissues and organs and travel to target cells in another part of the body to direct an activity i Examples glucagon and insulin