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FINAL EXAM - HNSC 1210 > Proteins & Amino Acids - Chapter 6 > Flashcards

Proteins & Amino Acids - Chapter 6 Flashcards

1
Q

Structure of the Basic Protein

A
  • Composed of carbon, hydrogen, oxygen and nitrogen
  • Arranged in strands of amino acids (AAs)
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2
Q

Basic Protein Structure & Function

A
  • All AAs have the same chemical backbone
    • A single carbon atom, with an amine group and an acid group attached
    • Each AA has a distinctive side chain which gives it its identity and chemical nature
    • The side chains make the AA differ in size, shape and electrical charge (positive, negative or neutral)
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3
Q

Basic Protein Structure
& Function (20 AAs)

A
  • 8 indispensable/essential, some may become
    conditionally essential (e.g., histidine)
  • Joined together by peptide bonds to form proteins
    • 2 AA = dipeptide
    • 3 AA = tripeptide
    • > 3 AA = polypeptide
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4
Q

Building Protein

A
  • AAs chemically attracted to or repelled from each
    other
    • Creates a coil shape
  • Spots along the coil attracted/repelled
    • Globular structure or fibrous structure
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5
Q

Sequence & Shape Determine Function

A
  • DNA (genetic sequence) determines the AA sequence in proteins
  • Specific structure/shape of proteins enables them to perform different tasks in the body
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6
Q

Function of Protein

A
  • Working proteins: enzymes, antibodies, hormones, oxygen carriers, etc.
  • Structural proteins: tendons, ligaments, fibres of muscles, found in our bones, teeth, hair and nails
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7
Q

Protein Synthesis Errors

A
  • For each protein, there exists a standard AA sequence which is specified by heredity
  • If a wrong AA is inserted = health consequence
    • E.g., genetic diseases
      - Sickle cell disease
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8
Q

Protein Digestion (Stomach)

A

Gastric acid (HCl) denatures protein, and pepsin (enzyme) cleaves some
peptide bonds

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9
Q

Protein Digestion (Small intestine lumen)

A

Pancreatic enzymes cleave polypeptides to di- and tri-peptides

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10
Q

Protein Digestion (Brush border membrane)

A

Enzymes cleave di- and tri-peptides to single AAs

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11
Q

Protein Absorption

A
  • Intestinal cells absorb AAs and some di- and tri peptides and release them into the bloodstream
  • Absorbing larger peptides may contribute to food allergies (immune response)
  • Carried to liver – used or released back into blood to be taken up by body cells
  • Body can reconnect AAs to make proteins
  • Body can use AA for energy if necessary
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12
Q

All Different Functions of Proteins (Part 1)

A
  1. Growth and maintenance
    • Structure, new tissue, repair (e.g., RBC lifespan is 90-120 days)
  2. Hormones and enzymes
    • E.g., growth factors, insulin
  3. Immune function
    • Antibodies
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13
Q

All Different Functions of Proteins (Part 2)

A
  1. Fluid and electrolyte balance
    • Protein transport
    • E.g., protein malnutrition and edema
  2. Acid-base balance
    • E.g., protein buffers
  3. Blood Clotting
    - Energy (Fig. 6-12)
    • Secondary function,
      only if diet is deficient
      in carbohydrate or total energy
    • No storage form of
      AAs
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14
Q

Protein Utilization (Build Protein)

A
  • AA used to build proteins
  • Converted to other small nitrogen-containing compounds, e.g.,
    vitamins (tryptophan → niacin)
  • Converted to other AAs
  • After removal of amino group:
    • Gluconeogenesis: carbon skeleton → glucose → blood
    • Lipogenesis: carbon skeleton → fat (for fuel or storage)
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15
Q

Protein Utilization (Waste)

A
  • AAs are wasted when:
    • Energy is lacking
    • Protein is overabundant
    • An AA is oversupplied (e.g., supplement)
    • Diet has too few essential AA (i.e., low protein quality)
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16
Q

Protein Utilization (Protein Synthesis)

A
  • To prevent wasting and permit protein synthesis:
    • Dietary protein must be adequate and supply all essential AA in proper amounts
    • Need adequate energy from carbohydrate and fat
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17
Q

Recommendations

A
  • Recommendations for intake:
    • DRI: 0.8g/kg body weight
      • Females: 46g/day
      • Males: 56g/day
    • DRI minimum amount: 10% total energy
      ◦ DRI maximum amount: 35% total energy
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18
Q

Protein Quality &
Quantity

A
  • Malnutrition:
    • Digestive enzyme secretion slows as the digestive tract lining degenerates, impairing protein digestion and absorption
  • Infection:
    • Protein is required to enhance immune function
  • Efficient use of protein:
    • Must be accompanied by the full array of vitamins and minerals
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19
Q

Protein Quality &
Quantity (factors)

A
  • Two factors influence protein quality:
    • Digestibility (improved by moist heat)
    • Animal protein:
      - >90% absorbed
    • Plant protein:
      - 70-90% absorbed
  • Amino acid composition
    • High-quality proteins contain ample amounts
      of all essential AAs
20
Q

Protein Quality &
Quantity (Complementary proteins)

A
  • 2 or more proteins whose AA structures supply the essential AAs missing from the other
  • Need complementary proteins in same day
21
Q

Measuring Protein
Quality (PDCAAS)

A
  • Protein digestibility corrected amino acid score:
    • Reflects protein digestibility
    • Proportion of AAs provided
22
Q

Measuring Protein
Quality (Scale 0-100)

A
  • Egg white, ground beef, chicken products, fat-free milk, tuna = 100
  • Soybean protein = 94
  • Wheat protein = 25
  • Combining complementary proteins can increase score
23
Q

Nitrogen Balance

A
  • Nitrogen intake compared to nitrogen excretion (through urine, feces,
    skin, sweat, body fluids)
    • Depends on size and stage of growth:
      - Equilibrium: normal healthy adult
      - Positive: growing child, pregnant individual
      - Negative: surgery patient, astronaut
24
Q

Protein Energy
Malnutrition (Marasmus)

A
  • <2 years age
  • Total diet deficiency
  • Slow, chronic
  • Severe weight loss
  • Muscle and fat loss
  • <60% weight for age
  • No edema
  • No fatty liver
  • Anxiety, apathy
  • Appetite varies
  • Hari, skin problems
25
Q

Protein Energy
Malnutrition (Kwashiorkor)

A
  • 1 – 3 years age
  • Protein deficiency
  • Rapid onset, acute
  • Some weight loss
  • Some muscle wasting
  • 60-80% weight for age
  • Edema
  • Fatty liver
  • Apathy, irritability
  • Loss of appetite
  • Hair, skin problems
26
Q

Protein Energy
Malnutrition

A
  • Worldwide:
    • 33,000 children die every day, many are malnourished
  • North America:
    • PEM associated with chronic disease, poverty, eating disorders
27
Q

What is Excess? (Protein Excess)

A

> 35% calories from protein

28
Q

High intakes of animal protein (Protein Excess)

A
  • Associated with obesity
  • Increased intake of saturated fat
  • Kidney and liver problems in animals
  • More bone mineral loss with high intakes of purified protein
  • More calcium lost in urine
  • Evidence mixed for effect of meat protein on Ca
29
Q

High intakes of protein (Protein Excess)

A
  • Worsen existing kidney disease in humans
  • Increase work of the kidney to excrete nitrogen wastes:
    • Amine group of AAs is excreted as ammonia or urea
  • Effective treatment for kidney problems = reduce protein intake
30
Q

High protein diets for weight loss (Protein Excess)

A
  • Protein used for energy and making glucose: must remove amino group and excrete it as urea via kidneys
  • Low CHO: if <130 g CHO/d, then no glycogen stores and “ketotic”
    • Body fat → ketone bodies for energy
    • Blood glucose made from
      • Dietary AAs (after meals)
      • Muscle protein (when post-absorptive), and this results in muscle wasting
31
Q

High Protein Diets

A
  • Initial rapid weight loss due to more water loss from body; loss of body fat and muscle mass in long term
  • Diet high in saturated fat: long term CVD risk?
  • Diet high in dietary cholesterol
  • Diet often low in some vitamins and minerals (e.g., calcium), and low in fibre
32
Q

Controversy 6: Vegetarian Diets (Vegetarian)

A
  • People choose vegetarian eating for many reasons:
    • Healthy eating
    • Culture
    • Ethics
    • Others?
33
Q

Controversy 6: Vegetarian Diets (TERMS TO KNOW - Vegetarian)

A

Plant-based foods, some or all animal foods eliminated

34
Q

Controversy 6: Vegetarian Diets (TERMS TO KNOW - Vegan)

A

Only food from plant sources (vegetables, grains, legumes, fruits, seeds, nuts,
etc.)

35
Q

Controversy 6: Vegetarian Diets (TERMS TO KNOW - Raw Vegan)

A

As above, but sprouted grains, and 75-100% of dietary intake is from uncooked food

36
Q

Controversy 6: Vegetarian Diets (TERMS TO KNOW - Lacto-ovo-vegetarian)

A

Eats dairy and eggs; no
flesh or seafood

37
Q

Controversy 6: Vegetarian Diets (TERMS TO KNOW - Lacto-vegetarian)

A

Eats dairy; no eggs, flesh, or
seafood

38
Q

Controversy 6: Vegetarian Diets (TERMS TO KNOW - Ovo-vegetarian)

A

Eats eggs; no milk products, flesh, or seafood

39
Q

Controversy 6: Vegetarian Diets (TERMS TO KNOW - Partial Vegetarian)

A

No red meat or limited
quantities

40
Q

Controversy 6: Vegetarian Diets (TERMS TO KNOW - Pesco-vegetarian/pescatarian)

A

No red meat or poultry

41
Q

Controversy 6: Vegetarian Diets (TERMS TO KNOW - Fruitarian)

A

Eats raw/dried fruit, seeds, nuts

42
Q

Controversy 6: Vegetarian Diets (TERMS TO KNOW - Macrobiotic Diet)

A

Progressively eliminates
foods → brown rice, herbal tea, water → malnutrition and death

43
Q

Controversy 6: Vegetarian Diets (Positive Health Aspects of Vegetarian Diets)

A
  • Reduced risk of disease (obesity, heart disease, diabetes, hypertension, cancer)
    • Diet is high in F&V, fibre, phytochemicals, some
      vitamins/minerals (e.g., A, C, folate)
    • Lifestyle often excludes smoking and alcohol, and
      emphasizes physical activity
  • Lower fat diet and leaner body composition
    • Maintain healthier body weight
    • Better control of caloric intake due to fibre-rich bulky foods?
44
Q

Controversy 6: Vegetarian Diets (Potential Pitfalls of Vegetarian Diets)

A
  • May be harder to meet additional requirements for pregnancy, breastfeeding, illness, etc.
  • Vitamin B12, vitamin D, Ca, Fe, Zn, and omega-3 fatty acid intakes may fall short,
    especially for infants, children, adolescents, and older adults
  • Requires careful planning
45
Q

Controversy 6: Vegetarian Diets (Summary)

A
  • Whichever diet you choose, important that diet is well planned to include all necessary nutrients
  • Aim for adequate, balanced, Calorie controlled, and varied
  • Use moderation when choosing foods high in saturated fat, sugar, salt, or Calories

FINAL EXAM - HNSC 1210 (7 decks)

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