Protein: Amino Acids Copyright 2005 Wadsworth Group, a division of Thomson Learning Amino acids: building blocks of protein

Amino Acids Copyright 2005 Wadsworth Group, a division of Thomson Learning Proteins: compounds composed of C, O, N, H atoms Arranged into amino acids linked in a chain.

Amino Acids Nonessential amino acids –a.k.a dispensable amino acids Essential amino acids –a.k.a indispensable amino acids Conditionally essential amino acids Copyright 2005 Wadsworth Group, a division of Thomson Learning

Extra Credit Which amino acid is not essential for adults, but is essential for infants?

Proteins Peptide bond –Unites each amino acid to the next –Connects the acid end of one aa to the amino end of another aa.

Proteins Dipeptide – two amino acids bonded together Copyright 2005 Wadsworth Group, a division of Thomson Learning

Proteins Tripeptide – three amino acids bonded together.

Proteins Polypeptide Copyright 2005 Wadsworth Group, a division of Thomson Learning

Proteins Amino acid sequences –Series of amino acids bonded together to make protein –Amino acids = letters of the alphabet –Proteins = words Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Review Proteins are made from… –Amino acids Two amino acids bonded together… –Dipeptide (for example: val-arg) The bond that link amino acids together –Peptide bond

What gives protein its shape and function? –Amino acid sequence

Copyright 2005 Wadsworth Group, a division of Thomson Learning Protein shape and function Amino acids sequence gives protein its shape and function

Proteins Protein denaturation –Uncoil and lose their shapes and loses its functions –Example: Heat Acid Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Digestion Stomach –HCl = uncoils, so enzymes can attack peptide bonds –Pepsinogen (proenzyme)  pepsin (active) HCl activates pepsinogen in the stomach Pepsin cleaves large polypeptides  smaller polypeptides and some amino acids. Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Digestion Small intestine –Proteases Intestinal and pancreatic Hydrolyze to tripeptides, dipeptides, and amino acids –Peptidases On membranes of intestinal cells split most dipeptides & tripeptides into amino acids ***Prepared and ready for absorption Copyright 2005 Wadsworth Group, a division of Thomson Learning

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Protein Digestion in the GI Tract

Protein Absorption Carriers – transport into intestinal cells and be used Capillaries – transport to liver Absorption misconceptions –Enzyme/amino acid supplements Copyright 2005 Wadsworth Group, a division of Thomson Learning

Roles of Proteins Building material –Growth: build bone –Maintenance: replacement, ie. dead skin cells, hair, fingernails. Copyright 2005 Wadsworth Group, a division of Thomson Learning

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Roles of Proteins Proteins act as enzymes and hormones Copyright 2005 Wadsworth Group, a division of Thomson Learning

Roles of Proteins Regulation of fluid balance Acid-base regulation Transporters for nutrients –Hemoglobin carries Fe Copyright 2005 Wadsworth Group, a division of Thomson Learning

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Roles of Proteins Immunity –Antibodies (proteins) –Antigens (invaders) Copyright 2005 Wadsworth Group, a division of Thomson Learning

Roles of Proteins Source of energy Other roles 3 general functions: –Maintenance & Growth –Regulatory –Energy Copyright 2005 Wadsworth Group, a division of Thomson Learning

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Protein Metabolism Protein turnover: process in which or body continually make and breakdown proteins. –Amino acid pool Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Metabolism Using amino acids to make proteins Using amino acids to make nonessential amino acids Copyright 2005 Wadsworth Group, a division of Thomson Learning

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Protein Metabolism Using amino acids to make other compounds –Neurotransmitters Tyrosine  epinephrine, nor- Using amino acids for energy and glucose Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Metabolism Deamination: N are stripped when aa are broken down –Ammonia  liver  urea  kidneys Using amino acids to make fat Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Quality High-quality proteins Digestibility –Animal vs. plant Amino acid composition –Limiting amino acid Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Quality Reference protein –How protein vs. requirement Complementary proteins Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Quality PDCAAS –Protein digestibility- corrected amino acid score Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein-Energy Malnutrition (PEM) Acute PEM Chronic PEM Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein-Energy Malnutrition (PEM) Marasmus Kwashiorkor Marasmus-kwashiorkor mix Copyright 2005 Wadsworth Group, a division of Thomson Learning

Marasmus

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Protein-Energy Malnutrition (PEM) Infections –Dysentery; infection of GI tract Rehabilitation Copyright 2005 Wadsworth Group, a division of Thomson Learning

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Health Effects Heart disease Cancer Adult bone loss –osteoporosis Copyright 2005 Wadsworth Group, a division of Thomson Learning

Health Effects Weight control Kidney disease Copyright 2005 Wadsworth Group, a division of Thomson Learning

Recommended Intakes RDA –0.8 g/kg/day –10% - 35% of energy intake Copyright 2005 Wadsworth Group, a division of Thomson Learning

Recommended Intakes Adequate intake Protein in abundance Copyright 2005 Wadsworth Group, a division of Thomson Learning

Supplements Protein supplements –Digestibility –Athletes –Initial body building Amino acid supplements –May cause an imbalance of other amino acids Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Synthesis Sequencing errors Copyright 2005 Wadsworth Group, a division of Thomson Learning

Vegetarian Diets Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Synthesis Delivering the instructions –DNA mRNA Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Synthesis Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Synthesis Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Synthesis Copyright 2005 Wadsworth Group, a division of Thomson Learning

Protein Synthesis Nutrients and gene expression Copyright 2005 Wadsworth Group, a division of Thomson Learning