NUTR 202 1nd EditionExam # 2 Study Guide Lectures: 11 - 17Ch 6 Proteins and Amino AcidsDiscussion: Disadv. Of Atkins Diet/ high protein: positives/negatives need supervision because don’t want to limit carbs to much for brain activity and RBCs. Try to maintain macronutrient distributions. May not be sustainable because limits majority of foods. Should you intake as much protein as possible to encourage muscle growth? Proteins are not stored! Carbs & fats are equally important. Not only in animals! Plants are also a great source of protein! • Proteins are the predominant structural and functional material in every cell• Proteins contains carbon, hydrogen, oxygen and a unique element: Nitrogen• Elemental component of proteins are amino acids: each has a carbon center, amine group (-NH2), acid group (COOH), hydrogen, unique side chain Twenty different amino acids found in proteins Nine amino acids are essential: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine. Eleven amino acids are nonessential:Can be synthesized in the body from other amino acids or by adding nitrogen to C-containing structuresSome amino acids are conditionally essential amino acids: Cannot be made in the body in adequate amounts under certain condition. Ex: Tyrosine is syn in liver from phenylalanine. Ppl with PKU cannot convert Phe to Tyr; therefore tyrosine is now a conditional essential aa. Connected by peptide bonds. Side chains can interact with each other. Can attract/repel/interact. Some side chains are hydrophilic or hydrophobic. Form specific 3D shapes due to interactions between the side chains of amino acids. Shape is critical to protein function. Definition of denaturation: alteration of a protein’s 3D structure includes: Heat (cooking), Mechanical Agitation(cooking & digestion), Acids, Salt, EnzymesWhat happens to the proteins you eat? Pepsin in stomach and HCl breakdown food.Absorption of AA requires Active Transport: requires energy and carrier molecule. This allows amino acids to move from area of high concentration to low concentrationProtein Absorption Competition in Brush Border: purple & green use same transport system; if consume more green  larger amt of green will limit the absorption of the purple ones. If body uses 100g from diet and 200g from breakdown of different body proteins  body is going to on avg use 300g. Majority is obtained from protein breakdown. If intake is more  eliminated. AA and proteins are not stored  become apart of pool for anabolic/catabolic reactions. Can be used to syn. new proteins. AA can be converted to glucose or catabolized complete to generate E. When E intake exceeds  converted to FAs and stored in adipose tissue. Must have amino acid pool first. Need to produce hemoglobin, syn. enzymes, syn. antibodies = main fxn.Synthesize new proteins: DNA in nucleus contains instructions for protein synthesis.First step –Transcription (location in nucleus) then Translation (location=ribosomes)1. Make mRNA 2. mRNA joins ribosome (protein maker) 3. tRNA delivers amino acidsProtein Functions: reiterate that proteins are needed for energy necessarily; has many other important functions. 1. Provide structural & mechanical support to body tissues (500,000 different proteins):  Key components of muscles, bones, skin, hair, nails… Collagen is the most abundant protein in your body=connective tissues.  Tissues and organs in our body are constantly broken down and repaired (protein turnover). We need structural proteins for growth and repair of tissues (severe burns)2. Transport substances throughout the body3. Build most enzymes and hormones4. Contribute to a healthy immune system (Abs)5. Maintain Fluid Balance: - Proteins help maintain acid-base balance- Protein improves satiety and appetite control- Blood clotting- Movement of muscles (actin & myosin)- Regulate chemical signals (hormones)- Can provide energy (4kcal/gram) yet we want proteins for their other functions!How much do you need? Healthy adults should consume enough dietary protein to replace the amount they use each day, whereas pregnant women, people recovering from surgery, and growing children need more protein to supply the necessary amino acids and nitrogen to build new tissue.Healthy adults have nitrogen balance, injury/illness cause negative balance and might have a lot of nitrogen in urea (secreting more than consuming), growth and development you have a positive balance (infancy/ adolescence). As you get older, unless you’re an athlete, the amount of protein you need will decrease.  Endurance athletes: 1.2 to 1.4 g/kg. Strength Athletes: 1.6 to 1.7 g/kg RDA: 0.8 g/kg of body weight/ day (for adults). With more weight, more protein is needed. To convert weight in pounds to kilograms (kg): Weight in lbs ¸ 2.2Increased needs: Infancy, Pregnancy / lactation, InjuryProblem/ Calculate: 140-pound adult female, healthy, not pregnant or lactating, regular physical activity (no competitive). Convert weight in # to kg: 140 lbs = 63.6 kg63.6 kg x 0.8 g/kg = ~51 g/day, anything above  excreted/ converted to triglycerides. Remember AMDR is 10-35%. Rec. for women is 50g and for men its 60g. Animal Foods: Most concentrated sources of Protein:• Eggs, Meat, Fish and Poultry= one ounce equals 7 grams of protein• Dairy Products: 1 serving= 1 cup of milk= 8 grams of protein• Low in fiber, high in cholesterol & saturated fats• Source of B vitamins, iron, zinc, calcium (absorbable form)Plant Foods: Less conc. sources of protein:• Nuts**, Legumes**, Grains, Vegetables • Low in fiber, high in cholesterol & saturated fats• Source of some B vitamins, iron, zinc, calcium (less absorbable form)• Excellent sources of fiber, phytochemicals, and unsaturated fats. Protein quality: Is a measure of how good the protein in a food is… at providing the essential amino acids the body needs to synthesize proteins. Digestibility & amino acid profile determine protein quality: 70-90% from plant digested vs. 90-99% from animalProteins that contain all of the essential amino acids with some nonessential ones: Complete dietary proteins=High Quality! Examples: Animal proteins, soy, possibly quinoa (not animal but contain those 2 factorsto be considered high quality). Incomplete Proteins: low in one or more essential aa, like plant proteins and can be “upgraded” or made complete with “complementary