1. Protein
Chapter 05

2. What Are Proteins? Nitrogen-containing macronutrient
Amino acid subunits
Peptide bond
Most abundant organic substance in body
Classification
Number of amino acids

3. What Are Proteins? Amino acid structure Common components
Central carbon bonded to hydrogen
Amino group
Nitrogen
R-group
Carboxylic acid group
Shape of protein imparts its function

4. Components of an Amino Acid

5. What Are Proteins? Amino acids Essential Nonessential
Nine
Nonessential
Eleven
Transamination
Conditionally essential
Six
PKU

6. Essential, Nonessential, & Conditionally Essential Amino Acids

7. What Are Proteins? Proteins of animal origin
Proteins found in plant-derived foods
Complete protein source
Balanced amount of essential amino acids
Incomplete protein source
Limiting amino acid
Protein complementation
Different incomplete proteins

8. How Do Cells Make Proteins?
Protein synthesis
Step 1: Cell signaling
Cellular needs conveyed to cell nucleus
Step 2: Transcription
mRNA is constructed using DNA as a template
Exits nucleus
Chromosome
Gene

9. How Do Cells Make Proteins?
Protein synthesis
Step 3: Translation
mRNA binds to a ribosome
tRNA
Carry amino acids to the ribosome
Peptide is released from ribosome

10. Protein Synthesis

11. Why Is a Protein’s Shape Critical to Its Function?
Primary structure
Number and sequence of amino acids in a single chain
Determined by DNA code
Critical to function
Sickle cell anemia

12. Primary Structure of Protein

13. Why Is a Protein’s Shape Critical to Its Function?
Secondary structure
α-helix
β-folded sheet
Tertiary structure
Interactions between R-groups

14. Secondary Structure of a Protein

15. Why Is a Protein’s Shape Critical to Its Function?
Quaternary structure
Two or more peptide chains join together
Not all proteins have this structure
Prosthetic groups
Often contain minerals
Denaturation
Denaturing agents

16. Quaternary Structure & Prosthetic Groups of Hemoglobin

17. What Is Meant by Genetics and Epigenetics?
Genotype
DNA
Phenotype
Physical characteristics
Mutations
Alteration in a gene
Inherited if present in DNA of egg or sperm

18. What Is Meant by Genetics and Epigenetics?
Alterations in protein synthesis not involving DNA sequence
May be passed on to next generation
Nutritional status
May impact long term epigenetic modifications

19. How Are Proteins Digested, Absorbed, & Circulate?
Digestion
Begins in the stomach
Gastrin
Hydrochloric acid
Disrupts chemical bonds
Converts proenzyme pepsinogen to pepsin
Pepsinogen
Proenzyme for pepsin

20. How Are Proteins Digested, Absorbed, & Circulate?
Digestion
Small intestine
In lumen and within cells
Secretin
Stimulates pancreas to release bicarbonate
Cholecystokinin (CCK)
Stimulates release of proenzymes from pancreas

21. Overview of Protein Digestion

22. How Are Proteins Digested, Absorbed, & Circulate?
Absorption
Amino acids are absorbed in the duodenum
Amino acids enter the bloodstream
Circulation
Travel to the liver for processing

23. How Are Proteins Digested, Absorbed, & Circulate?
Food allergy
Major allergens
Food labels
Immune response
Common signs and symptoms
Anaphylaxis
Food intolerance or sensitivity
Lactose intolerance

24. Why Do You Need Proteins and Amino Acids?
Structure
Structural materials of the body
Growth and development
Enzymes
Biological catalysts
Movement
Contraction and relaxation of muscles
Voluntary and involuntary movements
Actin and myosin

25. Why Do You Need Proteins and Amino Acids?
Transport
Escorting substances into and around the body
Secondary malnutrition
Communication
Hormones
Cell-signaling proteins
Protection
Antibodies

26. Why Do You Need Proteins and Amino Acids?
Fluid balance
Albumin
Edema
Regulation of pH
Source of glucose and energy
Proteolysis
Gluconeogenesis
Lipogenesis
Other purposes

27. Regulation of Fluid Balance by Albumin

28. Major Functions of Proteins in the Body

29. How Does the Body Recycle & Reuse Amino Acids?
Protein turnover
Adaptation to periods of growth and development
Nitrogen excretion
Ammonia
Liver converts to urea
Nitrogen balance & protein status
Negative nitrogen balance
Positive nitrogen balance

30. How Much Protein Do You Need?
Reasons to consume dietary protein
For adequate amounts of essential amino acids
For nitrogen
DRIs for amino acids
Milligrams per kilogram per day (mg/kg/day)
Set relative to body size
No ULs

31. RDAs for the Essential Amino Acids in Adults

32. How Much Protein Do You Need?
DRIs for protein
Expression
Grams per day (g/day)
Grams per kilogram body weight per day (g/kg/day)
Times for greater protein intake
No UL
Athlete protein needs
AMDRs

33. Can Vegetarian Diets Be Healthy?
Forms of vegetarianism
Lacto-ovo-vegetarian
Lactovegetarian
Vegan
Micronutrient deficiencies
Special recommendations for vegetarians
Enjoy assortment of foods
Consume foods in moderation

34. What Are the Consequences of Protein Deficiency & Excess?
Protein-energy malnutrition (PEM)
Micronutrient deficiencies
Risk for infection and illness
Marasmus
Severe, chronic, overall malnutrition
Kwashiorkor
Severe edema in extremities
Ascites

35. What Are the Consequences of Protein Deficiency & Excess?
Adults
Rarely experience kwashiorkor
Extreme muscle loss
Protein excess
High intakes of protein accompany high intakes of fat, saturated fat, & cholesterol
Red meat consumption
Cancer risk