Chapter four proteins and amino acids
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Chapter Four: Proteins and Amino Acids. Explain how the chemical structure of proteins differs from the other energy nutrients Identify and describe the multiple functions of protein in the body Explain the difference between essential and non-essential amino acids

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Chapter four proteins and amino acids
Chapter Four: Proteins and Amino Acids

  • Explain how the chemical structure of proteins differs from the other energy nutrients

  • Identify and describe the multiple functions of protein in the body

  • Explain the difference between essential and non-essential amino acids

  • Describe the concept of nitrogen balance


Proteins cntd
Proteins cntd.

  • Describe conditions associated with either positive or negative nitrogen balance

  • Describe causes and characteristics of marasmus and kwashiorkor

  • Explain what makes a protein complete and identify sources of them

  • Explain the types of vegetarian diets


What do you already know
What do you already know?

  • Proteins in Review

    • Energy provided: 4 kcal per gram

    • 12-15% of calories per day

  • Sources in the Food Guide Pyramid

    • Bread, Cereal, Rice and Pasta Group

    • Vegetable Group

    • Milk, Yogurt and Cheese Group

    • Meat and Meat Alternates Group


Chemical view of protein
Chemical View of Protein

  • Contains same elements as other energy nutrients (carbon, hydrogen and oxygen) plus nitrogen

  • Made up of building blocks called amino acids (20 amino acids)

    • Essential amino acids must be supplied in foods (9 are essential)

    • Non-essential am. acids—body can make


Nutritional role of proteins
Nutritional Role of Proteins

  • Primary function is to Build, Maintain, and Repair the Body — not to provideenergy

  • Enzymes: catalysts that facilitate chemical reactions

    • Anabolic—build body compounds

    • Catabolic—dismantle body compounds

      • Example—digestive enzymes


Nutritional roles cntd
Nutritional Roles cntd.

  • Fluid and Electrolyte Balance

    • Help maintain distribution of fluids in the body

    • Proteins are hydrophilic—water loving

  • Acid-Base Balance

    • Controls blood pH (acidity or alkalinity)

    • Release or bind hydrogen ions


Protein roles cntd
Protein roles cntd.

  • Antibodies

    • Formed from protein

    • Maintains resistance to disease

  • Hormones

    • Messenger molecules

    • Examples are insulin and thyroxin

  • Transport—carry other nutrients, e.g. oxygen, lipids, vitamins and minerals


Protein roles cntd1
Protein Roles cntd.

  • Nitrogen Balance—maintenance of same amount of protein in body tissues

    • Positive Balance—nitrogen in > nitrogen out

      • Growing children

      • Pregnant woman

    • Negative Balance—nitrogen in < nitrogen out

      • Fasting or starvation

      • Severe traumas—burns, tissue loss


Protein roles cntd2
Protein Roles cntd.

  • Zero balance

    • Nitrogen in = nitrogen out

    • Normal daily functioning

  • Measured by sample of body tissue or urine


Protein deficiency
Protein Deficiency

  • Marasmus

    • Energy deficiency common in young children ages 6-18 months

    • Food is low in kcalories and protein

  • Kwashiorkor: (Red hair)

    • Protein deficiency common in children after age two—after weaning

    • Symptoms: edema, distended abdomen and orange hair


Proteins in foods
Proteins in Foods

  • Complete Proteins:

    • Contain all essential amino acids

    • Sources are animal foods with the exception of gelatin

  • Incomplete Proteins:

    • Limited in amounts or number of essential amino acids

    • Sources are grains, vegetables and legumes


Protein sparing
Protein Sparing

  • Carbohydrate needed to spare protein from being used for energy

  • If protein is used for energy it is deaminized—nitrogen is removed—and the C, H, and O are used for energy

  • Low carbohydrate diets are not recommended for this reason


Vegetarian diets
Vegetarian Diets

  • Vegetarianism: rely mostly on non animal foods for their diet

  • Levels of Vegetarianism

    • Lacto-vegetarians—milk only

    • Lacto-ova—milk and eggs

    • Vegans—exclude all animal products

  • Advantages:

    • Easier to maintain desired weight

    • Lower cholesterol and higher fiber foods

    • Lower rates of colon cancer and heart disease

    • Better digestion—low fat and high fiber



Vegetarianism cntd
Vegetarianism cntd.

  • Nutritional concerns

    • Vitamin B12 only found in animal products

    • Vitamin D mainly available in milk and animal fats

    • Iron and Zinc are not as available in non-animal sources


Test questions
TEST Questions

  • 1. Proteins are chemically different from carbohydrates and fat because they also contain:

    • A. Phosphorus

    • B. Sodium

    • C. Iron

    • D. Nitrogen


Test questions1
Test Questions

  • 4. The basic building blocks of protein are:

  • a. glucose units

  • b. amino acids

  • c. side chains

  • d. saturated bonds


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