Protein
Chapter 5
What Are Proteins?
• Complex molecules
• Amino acids
• Peptide bonds
– Condensation reaction

• Nitrogen
• Classification
...
What Are Proteins?
• Amino acids
• Three common parts
• Central carbon bonded to a hydrogen
• Amino group (-NH2)
• Carboxy...
The Main Components of an
Amino Acid
What Are Proteins?
• Amino acids
• Classification
• Essential – 9 amino acids
• Nonessential – 11 amino acids
• Conditiona...
Essential, Nonessential, &
Conditionally Essential Amino Acids
Are All Food Proteins Equal?
• Categorization of food proteins
• Complete protein sources
• Sources
• Incomplete protein s...
How Are Proteins Made?
• Step 1: Cell signaling initiates protein synthesis
• Up-regulation
• Down-regulation
• Step 2: Tr...
The Steps of Protein Synthesis
How Do Proteins Get Their
Shapes?
• Protein structure
• Primary structure
• Number and sequence of amino acids
• Critical ...
The Primary Structure of a
Protein
The Secondary Structure of a
Protein
How Do Proteins Get Their
Shapes?
• Protein structure
• Tertiary structure
• Folding due to R-group interactions
• Quatern...
The Quaternary Structure &
Prosthetic Groups of Hemoglobin
Genetics, Epigenetics, Nutrition,
and Nutrigenomics
• Genetic alterations
• Mutations
• Chance genetic modification
• Poly...
Genetics, Epigenetics, Nutrition,
and Nutrigenomics
• Nutrigenomics
• How nutrition and genetics interact to influence
hea...
How Are Dietary Proteins
Digested, Absorbed, & Circulated?
• Chemical digestion begins in the stomach
• Gastrin
• HCl
– Di...
How Are Dietary Proteins
Digested, Absorbed, & Circulated?
• Protein digestion continued in small intestine
• In lumen and...
Overview of Protein Digestion
How Are Dietary Proteins
Digested, Absorbed, & Circulated?
• Absorption occurs in small intestine
• Transported from lumen...
How Are Dietary Proteins
Digested, Absorbed, & Circulated?
• Food intolerance
• Food allergy
•
•
•
•

Common allergens
Sig...
What Are the Major Functions of
Proteins & Amino Acids in the Body?

• Provide structure
• Important during periods of gro...
What Are the Major Functions of
Proteins & Amino Acids in the Body?

• Transport proteins
• Protein deficiency
• Communica...
What Are the Major Functions of
Proteins & Amino Acids in the Body?

• Fluid balance
• Intracellular vs. extracellular spa...
Regulation of Fluid Balance by
Albumin
Protein and Energy Metabolism
Protein Turnover, Urea
Excretion, and Nitrogen Balance
• Protein turnover
• Proteolysis
• Labile amino acid pool
• Regulat...
Urea Synthesis and Excretion
Protein Turnover, Urea
Excretion, and Nitrogen Balance
• Nitrogen balance
•
•
•
•

When protein loss equals protein intake...
How Much Protein Do You
Need?
• Reasons for protein consumption
• Essential amino acids
• Needed additional nitrogen
• DRI...
The RDAs for the Essential
Amino Acids in Adults
How Much Protein Do You
Need?
• Protein needs of athletes
• Debated among experts
• DRI committee
• International Society ...
Vegetarian Diets: Healthier Than
Other Dietary Patterns?
• Various forms of vegetarianism
• Lacto-ovo-vegetarian
• Lactove...
What Are the Consequences of
Protein Deficiency?
• Children are especially affected
• Protein-energy malnutrition (PEM)
• ...
Protein Excess: Is There Cause
for Concern?
• Not causally associated with adverse health
outcomes
• High protein intakes ...
Nutrition Matters
Food Safety
What Causes Foodborne
Illness?
• Foodborne illness
• Disease caused by ingesting unsafe food
• Causes
• Infectious agents
...
Infectious Agents of Foodborne Illness,
Food Sources, & Symptoms of Infection
Infectious Agents of Foodborne Illness,
Food Sources, & Symptoms of Infection
Infectious Agents of Foodborne Illness,
Food Sources, & Symptoms of Infection
What Causes Foodborne
Illness?
• Preformed toxins
• Serious and rapid reactions
• Staphylococcus aureus
• Toxin is not eas...
What Causes Foodborne
Illness?
• Preformed toxins
• Clostridium botulinum
• Food sources
• High cooking temperatures destr...
What Causes Foodborne
Illness?
• Enteric toxins
• Result in diarrhea in one to five days
• Noroviruses
• Symptoms
• Cannot...
What Causes Foodborne
Illness?
• Enterohemorrhagic
• Invasion of intestinal cells
• Signs and symptoms
• Salmonella
• Food...
What Causes Foodborne
Illness?
• Parasites
• Protozoa
• Cysts
• Giardia intestinalis
– Symptoms

• Worms
• Trichinella
• A...
What Causes Foodborne
Illness?
• Prions
• Altered proteins
•
•
•
•

• Secondary structure is disrupted
Resilient
Mad Cow d...
How Can Noninfectious Substances
Cause Foodborne Illness?

• Algae toxins
• Shellfish poisoning
• Marine toxins
• Red tide...
How Can Noninfectious Substances
Cause Foodborne Illness?

• Food allergies and sensitivities
• Monodosium glutamate (MSG)...
How Do Food Manufacturers
Prevent Contamination?
• Food-handling techniques
• Food production, preservation, and packaging...
Guidelines for Cooking, Serving, &
Reheating Foods to Prevent
Foodborne Illness
What Steps Can You Take to
Reduce Foodborne Illness?
• Check consumer advisory bulletins
• FightBac!
• Clean
•
•
•
•

• Ha...
What About Avoiding Foodborne
Illness While Traveling or Camping?

• Drink only purified or treated water
• Bottle water
•...
What Are Some Emerging
Issues of Food Biosecurity?
• Food biosecurity
• Prevention of terrorist attacks on food supply
• B...
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Chapter5

  1. 1. Protein Chapter 5
  2. 2. What Are Proteins? • Complex molecules • Amino acids • Peptide bonds – Condensation reaction • Nitrogen • Classification • Number of amino acids – Oligopeptides and polypeptides
  3. 3. What Are Proteins? • Amino acids • Three common parts • Central carbon bonded to a hydrogen • Amino group (-NH2) • Carboxylic acid (-COOH) • R-group
  4. 4. The Main Components of an Amino Acid
  5. 5. What Are Proteins? • Amino acids • Classification • Essential – 9 amino acids • Nonessential – 11 amino acids • Conditionally essential – 6 amino acids • Transamination • α-keto acid
  6. 6. Essential, Nonessential, & Conditionally Essential Amino Acids
  7. 7. Are All Food Proteins Equal? • Categorization of food proteins • Complete protein sources • Sources • Incomplete protein sources • Limiting amino acids • Protein complementation • Protein quality • High-quality vs. low-quality protein sources • GMOs
  8. 8. How Are Proteins Made? • Step 1: Cell signaling initiates protein synthesis • Up-regulation • Down-regulation • Step 2: Transcription transfers genetic info • Chromosomes and genes • Messenger ribonucleic acid (mRNA) • Step 3: Translation produces new peptide • Ribosomes • Transfer ribonucleic acid (tRNA)
  9. 9. The Steps of Protein Synthesis
  10. 10. How Do Proteins Get Their Shapes? • Protein structure • Primary structure • Number and sequence of amino acids • Critical to function of protein • Sickle cell anemia • Secondary structure • α-helix • β-folded sheets
  11. 11. The Primary Structure of a Protein
  12. 12. The Secondary Structure of a Protein
  13. 13. How Do Proteins Get Their Shapes? • Protein structure • Tertiary structure • Folding due to R-group interactions • Quaternary structure • Two or more peptide chains come together • Prosthetic groups • Denaturation • Denaturating agents • FDA and EPA recommendations
  14. 14. The Quaternary Structure & Prosthetic Groups of Hemoglobin
  15. 15. Genetics, Epigenetics, Nutrition, and Nutrigenomics • Genetic alterations • Mutations • Chance genetic modification • Polymorphism • Health and disease risks • Epigenetics • Connection between genes & physiology • Chronic degenerative disease risk
  16. 16. Genetics, Epigenetics, Nutrition, and Nutrigenomics • Nutrigenomics • How nutrition and genetics interact to influence health • Human Genome Project • Future for personalized nutrition
  17. 17. How Are Dietary Proteins Digested, Absorbed, & Circulated? • Chemical digestion begins in the stomach • Gastrin • HCl – Disrupts secondary, tertiary, and quaternary structures – Converts pepsinogen to pepsin • Pepsin – Breaks bonds between amino acids • Mucus and other substances
  18. 18. How Are Dietary Proteins Digested, Absorbed, & Circulated? • Protein digestion continued in small intestine • In lumen and enterocytes • Secretin and CCK • Pancreas releases bicarbonate • Pancrease releases proenzymes – Trypsin – Chymotrypsin – Elastase – Carboxypeptidase
  19. 19. Overview of Protein Digestion
  20. 20. How Are Dietary Proteins Digested, Absorbed, & Circulated? • Absorption occurs in small intestine • Transported from lumen into brush border cells • Passive and active transport mechanisms • Circulation • Circulated to liver via the hepatic portal system
  21. 21. How Are Dietary Proteins Digested, Absorbed, & Circulated? • Food intolerance • Food allergy • • • • Common allergens Signs and symptoms Anaphylaxis Best prevention is avoidance
  22. 22. What Are the Major Functions of Proteins & Amino Acids in the Body? • Provide structure • Important during periods of growth and development • Enzymes • Catalysts • Speed up chemical reactions • Facilitate movement • Skeletal muscle • Actin and myosin
  23. 23. What Are the Major Functions of Proteins & Amino Acids in the Body? • Transport proteins • Protein deficiency • Communication • Hormones • Cell-signaling process • Immune system • Antibodies
  24. 24. What Are the Major Functions of Proteins & Amino Acids in the Body? • Fluid balance • Intracellular vs. extracellular space • Intravascular vs. interstitial fluid • Edema • Regulate pH • Glucose synthesis and ATP production • Gluconeogenesis • Other purposes
  25. 25. Regulation of Fluid Balance by Albumin
  26. 26. Protein and Energy Metabolism
  27. 27. Protein Turnover, Urea Excretion, and Nitrogen Balance • Protein turnover • Proteolysis • Labile amino acid pool • Regulated by hormones • Urea excretion • Deamination • Ammonia (NH3) – Liver converts to urea
  28. 28. Urea Synthesis and Excretion
  29. 29. Protein Turnover, Urea Excretion, and Nitrogen Balance • Nitrogen balance • • • • When protein loss equals protein intake Measure of overall protein status Negative nitrogen balance Positive nitrogen balance
  30. 30. How Much Protein Do You Need? • Reasons for protein consumption • Essential amino acids • Needed additional nitrogen • DRIs for amino acids • RDAs • No ULs • DRIs for proteins • RDAs • Life stages with higher protein recommendations
  31. 31. The RDAs for the Essential Amino Acids in Adults
  32. 32. How Much Protein Do You Need? • Protein needs of athletes • Debated among experts • DRI committee • International Society of Sport Nutrition • American College of Sports Medicine • Supplements • Other recommendations • AMDRs • USDAs dietary source recommendations
  33. 33. Vegetarian Diets: Healthier Than Other Dietary Patterns? • Various forms of vegetarianism • Lacto-ovo-vegetarian • Lactovegetarians • Vegans • Deficiency risks • Key to a healthy vegetarian diet • Wide variety of foods in moderation
  34. 34. What Are the Consequences of Protein Deficiency? • Children are especially affected • Protein-energy malnutrition (PEM) • Micronutrient deficiencies • Types • Marasmus – Severe, chronic, overall malnutrition – Adults and children • Kwashiorkor – Edema and ascites
  35. 35. Protein Excess: Is There Cause for Concern? • Not causally associated with adverse health outcomes • High protein intakes often accompanied by high intakes of fat, saturated fat, and cholesterol • Intake of red meat or processed meats • Increased cancer risk • Recommendations
  36. 36. Nutrition Matters Food Safety
  37. 37. What Causes Foodborne Illness? • Foodborne illness • Disease caused by ingesting unsafe food • Causes • Infectious agents • Noninfectious agents • Strains of microorganisms • Serotypes – genetic strains or types • Incubation period
  38. 38. Infectious Agents of Foodborne Illness, Food Sources, & Symptoms of Infection
  39. 39. Infectious Agents of Foodborne Illness, Food Sources, & Symptoms of Infection
  40. 40. Infectious Agents of Foodborne Illness, Food Sources, & Symptoms of Infection
  41. 41. What Causes Foodborne Illness? • Preformed toxins • Serious and rapid reactions • Staphylococcus aureus • Toxin is not easily destroyed by cooking • Common foods • MRSA • “Community acquired” • MRSA-infected foods
  42. 42. What Causes Foodborne Illness? • Preformed toxins • Clostridium botulinum • Food sources • High cooking temperatures destroy the toxin • Disease of botulism • Aspergillus • Aflatoxin • Food sources
  43. 43. What Causes Foodborne Illness? • Enteric toxins • Result in diarrhea in one to five days • Noroviruses • Symptoms • Cannot be treated with antibiotics • Some serotypes of E. coli
  44. 44. What Causes Foodborne Illness? • Enterohemorrhagic • Invasion of intestinal cells • Signs and symptoms • Salmonella • Food sources • Incubation period • E. coli O157:H7 and E. coli O104:H4 • Incubation period • Food sources
  45. 45. What Causes Foodborne Illness? • Parasites • Protozoa • Cysts • Giardia intestinalis – Symptoms • Worms • Trichinella • Anisakis simplex
  46. 46. What Causes Foodborne Illness? • Prions • Altered proteins • • • • • Secondary structure is disrupted Resilient Mad Cow disease Creutzfelt-Jakob disease • Variant Creutzfeldt-Jakob disease WHO recommendations
  47. 47. How Can Noninfectious Substances Cause Foodborne Illness? • Algae toxins • Shellfish poisoning • Marine toxins • Red tide – Brevetoxins • • • • Pesticides Herbicides Antibiotics Hormones
  48. 48. How Can Noninfectious Substances Cause Foodborne Illness? • Food allergies and sensitivities • Monodosium glutamate (MSG) • Sulfites • Food proteins • New concerns • Acrylamide • Melamine • Bisphenol A (BPA)
  49. 49. How Do Food Manufacturers Prevent Contamination? • Food-handling techniques • Food production, preservation, and packaging • Hazard Analysis Critical Control Points • • • • • (HACCP) Salting, smoking, drying, and fermentation Heat treatment Pasteurization Cold treatment Irradiation
  50. 50. Guidelines for Cooking, Serving, & Reheating Foods to Prevent Foodborne Illness
  51. 51. What Steps Can You Take to Reduce Foodborne Illness? • Check consumer advisory bulletins • FightBac! • Clean • • • • • Hands, surfaces, and cooking utensils Wash • Fruits and vegetables Separate foods Cook foods to proper temperature Chill
  52. 52. What About Avoiding Foodborne Illness While Traveling or Camping? • Drink only purified or treated water • Bottle water • Avoid ice • Avoid or carefully wash fresh fruits & veggies • Avoid beef and beef products • Areas with variant Creutzfelt-Jakob disease
  53. 53. What Are Some Emerging Issues of Food Biosecurity? • Food biosecurity • Prevention of terrorist attacks on food supply • Bioterrorism Act • Changes in food production and distribution • Origin of food on label

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