Chapter 5: ProteinsProtein is an important part of a balanced diet and a vital macronutrient•ProteinsCarbon○Hydrogen○Oxygen○Unique to proteinNitrogen○Individual units of protein made up of:•4 kcal per gram○Energy not primary function○Protein also supplies energy:•List the elemental units of an amino acid.Building blocks for protein○Proteins are made up of combinations of amino acids linked together•Amino AcidsAmino group – has nitrogen○Acid group (carboxyl) – referenced as acid○Hydrogen group○Unique in each of the different amino acids R group (side chain)○All amino acids are made of a central carbon connected to four different groups •List the 4 different groups of each amino acidEssential and nonessential amino acidsNutrient that must be acquired by the dietEssential amino acids:○Can be made by the body in adequate amountsTransamination□Must move an amino group from one amino acid to a new compound make a nonessential amino acid:Nonessential amino acids:○Conditionally essential amino acidsIn rare circumstances, nonessential amino acids cannot be made by the body in the quantities needed. These amino acids are called:○Amino acids that make up proteins divided into 2 primary categories:•Define essential, non-essential and conditionally essential amino acids. Nutrition Page 1PVT TIM HALL○Arginine○Cysteine○Glutamine○Proline○Tyrosine○Nonessential amino acids•Identify essential amino acidsEvery protein in the body has a specific chain and sequence of amino acids.•Peptide bonds (amino -> carboxyl)○The acid group of one amino acid linked to the amine group of another○These amino acids are linked together by:•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)○The unique side chains (R group) of amino acids may or may not be able to mix with water.•Protein structureShape Dictates functionTherefore a predictable function○Correct sequence of amino acids results in predictable 3-D shape•This changes the function○Ex. Sickle cell anemiaIf incorrect, amino acid placed in sequence or is missing, the shape changes•Discuss why proteins have a 3 dimensional shape and how that shape affects the protein’s function Nutrition Page 2Ex. Sickle cell anemia○Denaturation○Changing the shape; this changes the function○Ex: Cooking an egg or stomach acid denatures proteins we eat○A protein’s structure can be changed by heat, acid, enzymes, agitation, or alcohol:•DenaturationPROTEIN FUNCTIONFunctions of Protein in the BodyList and describe the functions of proteins.Nuts, legumes•Albumin (protein that maintains fluid in vascular space)○Condition characterized by excess of watery fluid collecting in the cavities or tissues of the bodyEdema -> may develop if albumin in blood is low○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:•Protein Function: Fluid BalanceDefine edema and describe how it developsAs a normal part of the body’s chemical reactions, acids and bases are constantly being produced•Proteins act as buffers (raising-basic, lowering-acidic)○Serve to maintain pH in balance (meaning we stay neutral)○The body strives to maintain its pH, or its acid–base balance, in a tight range•Acid-base balanceForeign substance that triggers the responseAntigens (is what triggers immune response)○Foreign substances that enter our bodies that trigger the immune system:•Made up of amino acids○Traps bacteria and keep other foreign substances○Mucus present in the respiratory system and intestine is the body’s first defense mechanism•Antibodies○Proteins produced by the immune system as major defense against these foreign bodies:•Immune FunctionEnzymes:•Enzymes Nutrition Page 3Proteins 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○Enzymes:•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 •Messengers that help regulate the various systems and functions of the body○(Body’s traffic cop)Some hormones are made of lipids; while some, like insulin, are made from proteins○Hormones:•Hormonessodium-potassium pumps help maintain the balance of sodium and potassium between the outside and inside of the cell X○Proteins help transport substances across cell walls by acting as pumps•Ex: Retinol-binding protein○Proteins also serve as transporters of nutrients throughout the bloodstream•Lipoproteins – have phospholipids and proteins○Proteins have water-repelling and water-attracting ends, which allow them to interact with the fat and the water•TransportEnergy production is perhaps the least efficient purpose for proteins•Protein has no major storage form for immediate use•EnergyWhen energy from carbohydrate and fats are too low○… Animals store glucose as glycogen□Glucose can be released to raise blood cells□Muscle may be broken down to supply amino acids for energy○When will body use protein for energy:•Describe situations in which the body may use protein for energy.Protein TurnoverProtein synthesis○Body is constantly building and breaking of proteinsProtein breakdown○Protein turnover includes:•All essential amino acids must be present in adequate amounts for protein synthesis. •Limiting amino acid○Any amino acid not available in adequate amounts to make a particular protein:•Amino acid pool○Free amino acids temporarily available after protein is broken down and available for immediate use:•Describe protein turnover and the impact of a limiting amino acid.Deamination (stripping off the amino group)○Occurs primarily in the liver○Contains nitrogen (extra is eliminated in urine)Excreted in urineAmino group further converted to urea○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:•Protein intake relative to protein needs in the body:•Measuring Protein Turnover Nutrition Page 4Measure of nitrogen in (protein) vs. nitrogen lost