1. Protein
Chapter 5

2. What Are Proteins?
• Complex molecules
• Amino acids
• Peptide bonds
– Condensation reaction
• Nitrogen
• Classification
• Number of amino acids
– Oligopeptides and polypeptides

3. What Are Proteins?
• Amino acids
• Three common parts
• Central carbon bonded to a hydrogen
• Amino group (-NH2)
• Carboxylic acid (-COOH)
• R-group

4. The Main Components of an
Amino Acid

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. Essential, Nonessential, &
Conditionally Essential Amino Acids

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. 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. The Steps of Protein Synthesis

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. The Primary Structure of a
Protein

12. The Secondary Structure of a
Protein

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. The Quaternary Structure &
Prosthetic Groups of Hemoglobin

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. Genetics, Epigenetics, Nutrition,
and Nutrigenomics
• Nutrigenomics
• How nutrition and genetics interact to influence
health
• Human Genome Project
• Future for personalized nutrition

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. 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. Overview of Protein Digestion

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. How Are Dietary Proteins
Digested, Absorbed, & Circulated?
• Food intolerance
• Food allergy
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Common allergens
Signs and symptoms
Anaphylaxis
Best prevention is avoidance

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. 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. 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. Regulation of Fluid Balance by
Albumin

26. Protein and Energy Metabolism

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. Urea Synthesis and Excretion

29. Protein Turnover, Urea
Excretion, and Nitrogen Balance
• Nitrogen balance
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When protein loss equals protein intake
Measure of overall protein status
Negative nitrogen balance
Positive nitrogen balance

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. The RDAs for the Essential
Amino Acids in Adults

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. 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. 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. 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. Nutrition Matters
Food Safety

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. Infectious Agents of Foodborne Illness,
Food Sources, & Symptoms of Infection

39. Infectious Agents of Foodborne Illness,
Food Sources, & Symptoms of Infection

40. Infectious Agents of Foodborne Illness,
Food Sources, & Symptoms of Infection

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. What Causes Foodborne
Illness?
• Preformed toxins
• Clostridium botulinum
• Food sources
• High cooking temperatures destroy the toxin
• Disease of botulism
• Aspergillus
• Aflatoxin
• Food sources

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. 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. What Causes Foodborne
Illness?
• Parasites
• Protozoa
• Cysts
• Giardia intestinalis
– Symptoms
• Worms
• Trichinella
• Anisakis simplex

46. What Causes Foodborne
Illness?
• Prions
• Altered proteins
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• Secondary structure is disrupted
Resilient
Mad Cow disease
Creutzfelt-Jakob disease
• Variant Creutzfeldt-Jakob disease
WHO recommendations

47. How Can Noninfectious Substances
Cause Foodborne Illness?
• Algae toxins
• Shellfish poisoning
• Marine toxins
• Red tide
– Brevetoxins
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Pesticides
Herbicides
Antibiotics
Hormones

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. How Do Food Manufacturers
Prevent Contamination?
• Food-handling techniques
• Food production, preservation, and packaging
• Hazard Analysis Critical Control Points
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(HACCP)
Salting, smoking, drying, and fermentation
Heat treatment
Pasteurization
Cold treatment
Irradiation

50. Guidelines for Cooking, Serving, &
Reheating Foods to Prevent
Foodborne Illness

51. What Steps Can You Take to
Reduce Foodborne Illness?
• Check consumer advisory bulletins
• FightBac!
• Clean
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• Hands, surfaces, and cooking utensils
Wash
• Fruits and vegetables
Separate foods
Cook foods to proper temperature
Chill

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. 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