Chapter 5 Proteins Proteins Protein is an important part of a balanced diet and a vital macronutrient List the elemental units of an amino acid Individual units of protein made up of Carbon Hydrogen Oxygen Nitrogen Unique to protein Protein also supplies energy 4 kcal per gram Energy not primary function Amino Acids Proteins are made up of combinations of amino acids linked together Building blocks for protein List the 4 different groups of each amino acid All amino acids are made of a central carbon connected to four different groups Amino group has nitrogen Acid group carboxyl referenced as acid Hydrogen group R group side chain Unique in each of the different amino acids Essential and nonessential amino acids Define essential non essential and conditionally essential amino acids Amino acids that make up proteins divided into 2 primary categories Essential amino acids Nutrient that must be acquired by the diet Nonessential amino acids Can be made by the body in adequate amounts Must move an amino group from one amino acid to a new compound make a nonessential amino acid Transamination In rare circumstances nonessential amino acids cannot be made by the body in the quantities needed These amino acids are called Conditionally essential amino acids Nutrition Page 1 Identify essential amino acids PVT TIM HALL Nonessential amino acids Arginine Cysteine Glutamine Proline Tyrosine Protein structure Every protein in the body has a specific chain and sequence of amino acids These amino acids are linked together by Peptide bonds amino carboxyl The acid group of one amino acid linked to the amine group of another The unique side chains R group of amino acids may or may not be able to mix with water If not will move to inside of protein structure Forces the protein to fold into a 3 dimensional shape This shape determines the function of the protein influences the function Shape Dictates function Discuss why proteins have a 3 dimensional shape and how that shape affects the protein s function Correct sequence of amino acids results in predictable 3 D shape Therefore a predictable function If incorrect amino acid placed in sequence or is missing the shape changes This changes the function Ex Sickle cell anemia Nutrition Page 2 Ex Sickle cell anemia Denaturation A protein s structure can be changed by heat acid enzymes agitation or alcohol Denaturation Changing the shape this changes the function Ex Cooking an egg or stomach acid denatures proteins we eat PROTEIN FUNCTION Functions of Protein in the Body List and describe the functions of proteins Nuts legumes Protein Function Fluid Balance Proteins in the blood help keep an optimal balance between the fluids inside and outside your cells and blood vessels Primary protein that does this Albumin protein that maintains fluid in vascular space Edema may develop if albumin in blood is low Condition characterized by excess of watery fluid collecting in the cavities or tissues of the body Define edema and describe how it develops Acid base balance As a normal part of the body s chemical reactions acids and bases are constantly being produced The body strives to maintain its pH or its acid base balance in a tight range Proteins act as buffers raising basic lowering acidic Serve to maintain pH in balance meaning we stay neutral Immune Function Foreign substances that enter our bodies that trigger the immune system Antigens is what triggers immune response Foreign substance that triggers the response Mucus present in the respiratory system and intestine is the body s first defense mechanism Made up of amino acids Traps bacteria and keep other foreign substances Proteins produced by the immune system as major defense against these foreign bodies Antibodies Enzymes Enzymes Nutrition Page 3 Enzymes Proteins that speed up chemical reactions Made up of string of 100 and 1 000 amino acids Play vital roles that keep the body functioning optimally Sometimes a particular enzyme is not created because of a problem in genetic coding Other times the enzyme is damaged or levels are reduced by medications illness or inadequate nutrition Hormones Hormones Messengers that help regulate the various systems and functions of the body Some hormones are made of lipids while some like insulin are made from proteins Body s traffic cop Transport Proteins help transport substances across cell walls by acting as pumps sodium potassium pumps help maintain the balance of sodium and potassium between the outside and inside of the cell X Proteins also serve as transporters of nutrients throughout the bloodstream Ex Retinol binding protein Proteins have water repelling and water attracting ends which allow them to interact with the fat and the water Lipoproteins have phospholipids and proteins Energy Energy production is perhaps the least efficient purpose for proteins Protein has no major storage form for immediate use Describe situations in which the body may use protein for energy When will body use protein for energy When energy from carbohydrate and fats are too low Muscle may be broken down to supply amino acids for energy Animals store glucose as glycogen Glucose can be released to raise blood cells Protein Turnover Describe protein turnover and the impact of a limiting amino acid Protein turnover includes Protein synthesis Protein breakdown Body is constantly building and breaking of proteins All essential amino acids must be present in adequate amounts for protein synthesis Any amino acid not available in adequate amounts to make a particular protein Limiting amino acid Free amino acids temporarily available after protein is broken down and available for immediate use Amino acid pool Measuring Protein Turnover Extra amino acids not stored in they body Instead they may be broken down The amino group must be removed prior to elimination in a process known as Deamination stripping off the amino group Occurs primarily in the liver Amino group further converted to urea Contains nitrogen extra is eliminated in urine Excreted in urine Protein intake relative to protein needs in the body Nutrition Page 4 Protein intake relative to protein needs in the body Nitrogen balance Measure of nitrogen in protein vs nitrogen lost deaminated Protein Turnover and Nitrogen Balance Positive and Negative Nitrogen Balance Describe nitrogen balance and provide examples of when a person may be in positive nitrogen balance and negative nitrogen balance When intake is more than what is excreted