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Protein: Amino Acids

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Protein: Amino Acids Chapter 6 Protein-Energy Malnutrition (PEM) Insufficient intake of protein, energy, or both Prevalent form of malnutrition worldwide Impact on ... – PowerPoint PPT presentation

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Title: Protein: Amino Acids


1
Protein Amino Acids
  • Chapter 6

2
The Chemists View of Proteins
  • Atoms
  • Carbon, hydrogen, oxygen, nitrogen
  • Amino acids
  • Carbon
  • Hydrogen
  • Amino group
  • Acid group
  • Side group or side chain

3
The Chemists View of Proteins
4
The Chemists View of Proteins
  • More complex than carbohydrates or fats
  • Twenty amino acids
  • Different characteristics
  • Essential amino acids
  • Nonessential amino acids
  • Conditionally essential

5
The Chemists View of Proteins
6
The Chemists View of Proteins
  • Proteins
  • Peptide bonds link amino acids
  • Condensation reactions
  • Amino acid sequencing
  • Primary structure chemical bonds
  • Secondary structure electrical attractions
  • Tertiary structure hydrophilic hydrophobic
  • Quaternary structure two or more polypeptides

7
The Chemists View of Proteins
8
The Chemists View of Proteins
  • Protein
  • Denaturation
  • Disruption of stability
  • Uncoil and lose shape
  • Stomach acid

9
Protein Digestion
  • Mouth
  • Stomach
  • Hydrochloric acid denatures proteins
  • Pepsinogen to pepsin
  • Small intestine
  • Hydrolysis reactions
  • Peptidase enzymes

10
Protein Digestion
11
Protein Absorption
  • Transport into intestinal cells
  • Uses of amino acids by intestinal cells
  • Unused amino acids transported to liver
  • Enzyme digestion
  • Predigested proteins

12
Protein Synthesis
  • Uniqueness of each person
  • Amino acid sequences of proteins
  • Genes DNA
  • Diet
  • Adequate protein
  • Essential amino acids

13
(No Transcript)
14
Protein Synthesis
  • DNA template to make mRNA
  • Transcription
  • mRNA carries code to ribosome
  • Ribosomes are protein factories
  • mRNA specifies sequence of amino acids
  • Translation
  • tRNA
  • Sequencing errors

15
Protein Synthesis
16
Protein Synthesis
  • Gene expression and protein synthesis
  • Capability of body cells
  • Protein needs
  • Dietary influence on gene expression
  • Disease development

17
Roles of Proteins
  • Growth and maintenance
  • Building blocks for most body structures
  • Collagen
  • Replacement of dead or damaged cells
  • Enzymes
  • Break down, build up, and transform substances
  • Catalysts

18
Roles of Proteins
19

The separate compounds, A and B, are attracted to
the enzymes active site, making a reaction
likely.
The enzyme forms a complex with A and B.
The enzyme is unchanged, but A and B have formed
a new compound, AB.
Stepped Art
Fig. 6-9, p. 181
20
Roles of Proteins
  • Hormones
  • Messenger molecules
  • Transported in blood to target tissues
  • Regulators of fluid balance
  • Edema
  • Acid-base regulators
  • Attract hydrogen ions
  • Transporters specificity

21
Roles of Proteins
22
Roles of Proteins
  • Antibodies
  • Defend body against disease
  • Specificity
  • Immunity memory
  • Energy and glucose
  • Starvation and insufficient carbohydrate intake
  • Other roles

23
Preview of Protein Metabolism
  • Protein turnover amino acid pool
  • Continual production and destruction
  • Amino acid pool pattern is fairly constant
  • Used for protein production
  • Used for energy if stripped of nitrogen
  • Nitrogen balance
  • Zero nitrogen balance
  • Positive and negative nitrogen balance

24
Preview of Protein Metabolism
  • Making other compounds
  • Neurotransmitters
  • Melanin
  • Thyroxin
  • Niacin
  • Energy and glucose
  • Wasting of lean body tissue
  • Adequate intake of carbohydrates and fats

25
Preview of Protein Metabolism
  • Making fat
  • Energy and protein exceed needs
  • Carbohydrate intake is adequate
  • Can contribute to weight gain
  • Deaminating amino acids
  • Stripped of nitrogen-containing amino group
  • Ammonia
  • Keto acid

26
Preview of Protein Metabolism
  • Make proteins nonessential amino acids
  • Breakdown of proteins
  • Keto-acids
  • Liver cells and nonessential amino acids
  • Converting ammonia to urea
  • Liver ammonia and carbon dioxide
  • Dietary protein

27
Preview of Protein Metabolism
28
Preview of Protein Metabolism
29
Preview of Protein Metabolism
  • Excreting urea
  • Liver releases urea into blood
  • Kidneys filter urea out of blood
  • Liver disease
  • Kidney disease
  • Protein intake and urea production
  • Water consumption

30
Preview of Protein Metabolism
31
Protein Quality
  • Two factors
  • Digestibility
  • Other foods consumed
  • Animal vs. plant proteins
  • Amino acid composition
  • Essential amino acid consumption
  • Nitrogen-containing amino groups
  • Limiting amino acid

32
Protein Quality
  • Reference protein
  • Preschool-age children
  • High-quality proteins
  • Animal proteins
  • Plant proteins
  • Complementary proteins
  • Low-quality proteins combined to provide adequate
    levels of essential amino acids

33
Protein Regulations for Food Labels
  • Quantity of protein in grams
  • Percent Daily Value
  • Not mandatory
  • Protein claims
  • Consumption by children under 4 years old
  • Quality of protein

34
Protein-Energy Malnutrition (PEM)
  • Insufficient intake of protein, energy, or both
  • Prevalent form of malnutrition worldwide
  • Impact on children
  • Poor growth
  • Most common sign of malnutrition
  • Impact on adults
  • Conditions leading to PEM

35
Protein-Energy Malnutrition (PEM)
  • Marasmus
  • Chronic PEM
  • Children 6 to 18 months
  • Poverty
  • Little old people just skin and bones
  • Impaired growth, wasting of muscles, impaired
    brain development, lower body temperature
  • Digestion and absorption

36
Protein-Energy Malnutrition (PEM)
  • Kwashiorkor
  • Acute PEM
  • Children 18 months to 2 years
  • Develops rapidly
  • Aflatoxins
  • Edema, fatty liver, inflammation, infections,
    skin and hair changes, free-radical iron
  • Marasmus-Kwashiorkor mix

37
Protein-Energy Malnutrition (PEM)
38
Protein-Energy Malnutrition (PEM)
  • Infections
  • Degradation of antibodies
  • Dysentery
  • Heart failure and death
  • Rehabilitation
  • Rehydration and nutrition intervention
  • Add protein slowly

39
Health Effects of Protein
  • High-protein diets
  • Heart disease
  • Animal-protein intake
  • Homocysteine levels
  • Arginine levels
  • Cancer
  • Protein-rich foods not protein content of diet
  • Kidney disease
  • Acceleration of kidney deterioration

40
Health Effects of Protein
  • High-protein diets
  • Osteoporosis
  • Calcium excretion increases
  • Ideal ratio has not been determined
  • Animal protein intake
  • Weight control
  • Satiety

41
Recommended Intakes of Protein
  • Need for dietary protein
  • Source of essential amino acids
  • Practical source of nitrogen
  • 10 to 35 percent of daily energy intake
  • RDA
  • Adults 0.8 grams / kg of body weight / day
  • Groups with higher recommended intakes
  • Assumptions

42
Recommended Intakes of Protein
  • Protein in abundance
  • Intake in U.S. and Canada
  • Dietary sources
  • Serving sizes
  • Key diet principle moderation

43
Protein and Amino Acid Supplements
  • Protein powders
  • Muscle work vs. protein supplements
  • Athletic performance
  • Whey protein
  • Impact on kidneys
  • Amino acid supplements
  • Potential risks associated with intake
  • Lysine tryptophan

44
Highlight 6
  • Nutritional Genomics

45
Nutritional Genomics
  • New field
  • Nutrigenomics
  • Nutrients influence gene activity
  • Nutrigenetics
  • Genes influence activity of nutrients
  • Human genome

46
Nutritional Genomics
47
A Genomics Primer
  • DNA
  • 46 chromosomes
  • Nucleotide bases
  • Gene expression
  • Genetic information to protein synthesis
  • Gene presence vs. gene expression
  • Epigenetics
  • DNA methylation

48
A Genomics Primer
49
Genetic Variation and Disease
  • Genome variation
  • About 0.1 percent
  • Goal of nutritional genomics
  • Customize recommendations that fit individual
    needs
  • Single-gene disorders
  • Phenylketonuria (PKU)

50
Genetic Variation and Disease
  • Multigene disorders
  • Study expression and interaction of multiple
    genes
  • Sensitive to environmental influences
  • Example
  • Heart disease
  • Single nucleotide polymorphisms (SNPs)
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