NUTR 470 1st EditionExam # 3 Study Guide Lectures: 18 - 22Function of protein in our body: ___ & ____of body tissue. Proper functioning of _____ that resist infection _____ of enzymes and hormonesGrowth and Repair; antibodies, regulationThe 9 Essential Amino Acidshistidine,isoleucine,leucine,lysine, methionine, phenylalanine, threonine, tryptophan, andvaline.Foods of high protein quality include all of the __________.essential amino acidsSources of high-quality protein: ______ sources of proteins have the complete complement of all twenty amino acids.AnimalPlant sources of protein: With the exception of _____, plant sources of protein do not provide all nine essential amino acids.Combinations of plant foods, such as grains and seeds with dried beans, however, yield high-quality protein. soybeansRDA for protein?0.8 grams per kg body weightNitrogen balance— expresses the balance between anabolism and catabolism of nitrogen.Protein requirement can be measuring this. Input - Outputindicates net storage of nitrogenous compounds:Pregnancy?These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Illness?Starvation?Wounding?Positive NBNegative NBNegative NBNegative NBThe 3 Branched-chain amino acids?Leucine, Isoleucine, and ValineArginine— is a precursor of nitric oxide, which causes blood vessel relaxation (vasodilation). may be useful in the treatment of medical conditions that are improved byvasodilation, such as atherosclerosis, coronary artery disease, vascular disease, and vascular headache.Leucineis not produced by the human body; is found in protein-rich animal foods such as beef, chicken, fish, dairy, and eggs.Healthy foods:___ glycemic index, ____ in fiber____ in n-3 fatty acids, ____ in trans fat____ proteinLow, HighHigh, LowHighProteins are broken down to peptide fragments by pepsin in the _____ , and by pancreatic trypsin and chemotrypsin in the ________.stomachsmall intestineEndopeptidases—hydrolyze peptide bonds between specific amino acids throughout themolecule. are the first enzymes to act, yielding a larger number of smaller fragmentsEndopeptidases:_____ in the gastric juice____, _______, and ______ secreted into small intestine by the pancreas.Pepsintrypsin, chymotrypsin, and elastaseExopeptidases— catalyze the hydrolysis of peptide bonds, one at a time, from the ends of peptidesExopeptidases: _________, secreted in the pancreatic juice, release amino acid from the free carboxyl terminal; ________, secreted by the intestinal mucosal cells, release amino acids from the amino terminalCarboxypeptidasesaminopeptidases Dipeptidases— Exopeptidase: in the brush border of intestinal mucosal cells catalyze the hydrolysis of dipeptides, which are not substrates for amino- and carboxypeptidases.The proteases are secreted as ________________.inactive zymogens.In the stomach, pepsinogen is activated to ____ by gastric acid and by activated pepsin (autocatalysis). pepsinIn the small intestine, ______, is activated by enteropeptidase; trypsin can then activate _______ to chymotrypsin,______ to elastase, ______ to carboxypeptidase, and ______to aminopeptidase.trypsinogen; chymotrypsinogen; proelastase; procarboxypeptidase ; proaminopeptidaseProtein digestion typically begins in the _____, and continues in the ________. stomachsmall intestineThe proteolysis in the ________ plays the major role, because the digestion and absorption of dietary protein is not impaired by total absence of pepsin.small intestineThe end product of the action of endopeptidases and exopeptidases is a mixture of whatfour things?free amino acids, dipeptides, tripeptides, and oligopeptdies.Free amino acids are absorbed across the intestinal mucosa by sodium-dependent _______.active transport________ is more important for the basolateral transport, especially for amino acids with hydrophobic side chains. DiffusionTransamination— is the reaction between an amino acid and an alpha-keto acid. typically initiates amino acid catabolism.Oxidative deamination— Removal of the amine from glutamate produces an ammoniumion.The _____ formed by transamination can be oxidized completely into carbon dioxide and water by the citric acid cycle. keto-acidsWhen proteins are in excess, amino acids are converted into pyruvate and acetyl-CoA, and then into lipids by the ______ process.lipogenesisIf carbohydrates are lacking in the diet or if glucose cannot get into the cells (as indiabetes), ______ are converted into pyruvate and oxaloacetate, and then intoglucose.amino acidsA glucogenic amino acid— is an amino acid that can be converted into glucose through gluconeogenesis; Important ones: glycine, alanineWhat 3 enzymes occupy central positions in amino acid biosynthesis.Glutamate dehydrogenase, glutamine synthase, and aminotransferaseThe most common amino acid and α-keto acid in transamination reactions is _____ and________, which participate in reactions with many different aminotransferases.glutamateα-ketoglutarateAlanine a minotransferaseTransamination reaction:Puruvate<—ALT—>L-Alanine; Glutamate<——————>Alpha-ketoglutarate is present predominantly in the liver.Glucose-Alanine Cycle— Shows how skeletal muscle provides energy and how gets rid of nitrogen. In the human body, deamination takes place in the ______.liverHepatic glutamate dehydrogenase (GDH)Deamination:Glutamate———>alpha-ketoglutarate catalyzes the release of nitrogen as ammonia.Significance of Transamination and Deamination:Detox and production of energyDetoxificationSignificance of Transamination and Deamination:In times of dietary surplus, the potentially toxic nitrogen of amino acids is eliminated via transamination, deamination, and urea formation.Production of energySignificance of Transamination and Deamination:In times of dietary surplus, the carbon skeletons are generally conserved as fatty acid via fatty acid synthesis pathways (lipogenesis). Upon fasting or starvation, protein (amino acids) are converted to glucose, via gluconeogenesis, to provide a fuel.Ammonia— is an important source of nitrogen for living systems.Glucose-alanine cycle— is used primarily as a mechanism for skeletal muscle to eliminate nitrogen.Urea— is the major end product of nitrogen catabolism.In the liver:Conversion of _____ to ______ produces free ammonia, which is then converted to urea through urea cycle.glutamineglutamate1st