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Chapter 3: Nutrition

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Title: Chapter 3: Nutrition


1
Chapter 3 Nutrition
  • Leaving Certificate Biology
  • Higher Level

2
Function of Food
  • Food is a complex of chemicals required by a
    living organism to maintain metabolism and
    continuity of life

3
Common Elements in Food
  • Carbon C
  • Hydrogen H
  • Oxygen O
  • Nitrogen N
  • Phosphorus P
  • Sulphur S

4
Elements in Food as Dissolved Salts
  • 5 elements present in dissolved salts
  • Sodium Na
  • Magnesium Mg
  • Calcium Ca
  • Potassium K
  • Chlorine Cl

5
Trace minerals
  • 3 trace elements (minerals) present in living
    organisms
  • Iron Fe
  • Copper Cu
  • Zinc Zn

6
Biomolecules
  • Biomolecules are chemicals found in and produced
    by living organisms
  • There are 4 major types of biomolecules
  • Carbohydrates
  • Lipids
  • Proteins
  • Vitamins

7
Carbohydrates
  • C, H, O Ratio Cx(H2O)y
  • Three categories
  • Monosaccharides
  • Disaccharides
  • Polysaccharides (CH2O)n

8
Monosaccharides
  • Glucose C6H12O6 - a reducing sugar and formed
    by breakdown of glycogen
  • Fructose C6H12O6 - a reducing sugar and found
    in many fruits
  • Galactose C6H12O6 - a reducing sugar and formed
    by breakdown of lactose (found in milk)

9
Disaccharides
  • Maltose (a reducing sugar)
  • Found in germinating seeds (e.g. barley)
  • Glucose Glucose ? Maltose C12H22O11 H2O
  • Sucrose (NOT a reducing sugar)
  • Commonly known as table sugar
  • Glucose Fructose ? Sucrose C12H22O11 H2O
  • Lactose (a reducing sugar)
  • Found in milk - some people have
    lactose-intolerance
  • Glucose Galactose ? Lactose C12H22O11 H2O

10
Polysaccharides
  • Starch (also known as amylose)
  • Plants store glucose as starch, e.g. potatoes,
    bananas
  • Long chains and some branching of glucose
    molecules making it easy to digest
  • Cellulose (also known as fibre/roughage)
  • Found in cell walls and stems of plants such as
    celery
  • Composed of many glucose molecules bonded
    together in long chains making it difficult to
    digest
  • Glycogen
  • Animals store glucose as glycogen in liver and
    muscles
  • Glycogen is more branched than starch

11
Structural and Metabolic roles of Carbohydrates
  • Structural role
  • Cellulose component of cell walls keeps plant
    upright
  • Metabolic role
  • Energy Mono-, Di-, and Polysaccharides are
    metabolised to release energy

12
Lipids
  • Lipids consist of the elements C, H, and O, but
    have fewer O atoms than carbohydrates
  • Two main categories
  • Triglycerides
  • Phospholipids
  • Food sources of lipids
  • Butter, oils, margarines, cream, olives, animal
    fat

13
Triglycerides
  • Triglycerides one molecule of glycerol linked to
    three fatty acid molecules
  • Fats solid at room temperature (RT)
  • Oils liquids at RT - contain different types of
    fatty acids than fats

Glycerol
Fatty acid 1
Fig. 1 A Triglyceride
Fatty acid 2
Fatty acid 3
14
Phospholipids
  • Phospholipids one fatty acid replaced by a
    phosphate

Glycerol
Fatty acid 1
Fig. 2 A Phospholipid
Fatty acid 2
P
15
Structural and Metabolic roles of Lipids
  • Structural role
  • Phospholipids component of cell membranes of all
    living cells
  • Triglycerides form adipose tissue that surrounds
    important internal organs and acts as a shock
    absorber
  • Metabolic role
  • Energy triglycerides are stored by organisms as
    a source of energy

16
Proteins
  • Proteins consist of elements C, H, O, N - no
    particular ratios
  • Sulfur and phosphorus are also present in some
    proteins
  • There are 20 common amino acids found in proteins
  • Two main categories of protein
  • Fibrous proteins - little or no folding (e.g.
    proteins found in hair, skin nails)
  • Globular proteins - lots of folding (e.g. protein
    hormones, enzymes and antibodies)

17
Structural and Metabolic roles of Proteins
  • Structural role
  • Skin, nails and hair contain keratin
  • Muscle composed of actin and myosin
  • Bone, ligaments and tendons contain collagen
  • Metabolic role
  • Enzymes, antibodies and some hormones are proteins

18
Vitamins
  • Complex organic substances needed only in tiny
    amounts
  • Share no common chemical characteristics - all
    chemically unique
  • Identified by letters based on their chemical
    structure
  • A, D, E, and K are fat-soluble vitamins
  • B-group and C are water-soluble vitamins

19
1.3.6 Structural Role of Biomolecules
Vitamins
  • Structural role
  • Vitamins do not have any structural role in
    living organisms

20
1.3.7 Metabolic Role of Biomolecules
Vitamins
  • Metabolic role
  • Homeostasis and normal metabolism
  • Note for the Leaving Certificate you need to
    know one fat-soluble and one water-soluble
    vitamin, their functions, and the diseases caused
    by their deficiency

21
1.3.7 Metabolic Role of Biomolecules
  • Vitamin A
  • Properties
  • Fat-soluble 2 types retinol (from animal
    sources) and carotene (from plant sources)
    stored in liver
  • Functions
  • Necessary for healthy epithelia tissue skin,
    retina (vision) bone growth energy regulation
    antioxidant
  • Sources
  • Animal products liver, eggs, milk
  • Fruit and vegetables carrots, tomatoes, sweet
    potatoes, apricots
  • Symptoms of vitamin A deficiency
  • Night-blindness
  • Brain and spinal cord injury in infants

22
1.3.7 Metabolic Role of Biomolecules
  • Vitamin D
  • Properties
  • Fat-soluble 2 types
  • D2 (ergocalciferol - produced by UV action on
    skin)
  • D3 (cholecalciferol - from animal sources)
  • Functions
  • Necessary for proper uptake of calcium, teeth and
    bone growth and bone mineralisation
  • Sources
  • Main source is sunlight action on skin cod liver
    oil
  • Symptoms of vitamin D deficiency
  • Rickets in children
  • Osteomalacia in adults (more frequent in women)

23
1.3.7 Metabolic Role of Biomolecules
  • Vitamin E (tocopherol)
  • Properties
  • Fat-soluble stored in adipose tissue
  • Functions
  • Antioxidant - protects important biomolecules
    such as protein and DNA from oxidation (damage)
  • Sources
  • Vegetable oils, leafy green vegetables
  • Whole grains, wheat germ, milk, eggs, meat, fish
  • Symptoms of vitamin E deficiency
  • Muscle weakness and muscular dystrophy
  • Sterility in animals
  • Anaemia in infants

24
1.3.7 Metabolic Role of Biomolecules
  • Vitamin K fat-soluble in its natural form
  • Properties 3 types
  • K1 fat-soluble food-based
  • K2 fat-soluble made by bacteria found in the
    gut
  • K3 water-soluble man-made 2-3 times more
    potent than K1 and K2
  • Functions
  • Blood clotting
  • Sources
  • K1 liver and green vegetables K2 intestinal
    bacteria
  • Symptoms of vitamin K deficiency
  • Bleeding - inability of wounds to form clots

25
1.3.7 Metabolic Role of Biomolecules
  • Vitamin B Complex Vitamins 8 types
  • Thiamine (Vitamin B1)
  • Riboflavin (Vitamin B2)
  • Niacin/Nicotinic acid/Nicotinate (Vitamin B3)
  • Pyridoxine (Vitamin B6)
  • Folic acid/Folate
  • Cyanocobalamin (Vitamin B12)
  • Pantothenic acid/Pantothenate
  • Biotin
  • Functions
  • All 8 vitamins of the B group function as
    coenzymes (activate enzymes) involved in
    carbohydrate, protein and DNA metabolism

26
1.3.7 Metabolic Role of Biomolecules
  • Thiamine (Vitamin B1)
  • Properties
  • Water-soluble
  • Function
  • Coenzyme in carbohydrate metabolism
  • Sources
  • Pork, wheat germ, yeast, black beans, sunflower
    seeds
  • Symptoms of vitamin B1 deficiency
  • Beriberi (neurological and cardiovascular
    abnormalities)

27
1.3.7 Metabolic Role of Biomolecules
  • Riboflavin (Vitamin B2)
  • Properties
  • Water-soluble
  • Function
  • Coenzyme in protein metabolism
  • Sources
  • Organ meats, milk, vegetables
  • Symptoms of vitamin B2 deficiency
  • Ariboflavinosis (lesions in mouth and lips)

28
1.3.7 Metabolic Role of Biomolecules
  • Niacin/Nicotinic Acid/Nicotinate (Vitamin B3)
  • Properties
  • Water-soluble
  • Function
  • Coenzyme in carbohydrate metabolism
  • Sources
  • Meat, peanuts, coffee
  • Symptoms of vitamin B3 deficiency
  • Pellagra (dermatitis diarrhoea, dementia)

29
1.3.7 Metabolic Role of Biomolecules
  • Pyridoxine (Vitamin B6)
  • Properties
  • Water-soluble
  • Function
  • Coenzyme in protein metabolism
  • Sources
  • Pork, liver, bananas, whole grains
  • Symptoms of vitamin B6 deficiency
  • Extremely rare no specific term for B6
    deficiency symptoms include dermatitis and
    convulsions

30
1.3.7 Metabolic Role of Biomolecules
  • Folic Acid/Folate
  • Properties
  • Water soluble
  • Function
  • Necessary for DNA replication formation of RBCs
  • Sources
  • Liver, green leafy vegetables
  • Symptoms of Folic Acid deficiency
  • Swollen tongue, heart-burn, diarrhoea, fatigue,
    depression, megaloblastic anaemia, spina bifida
    (which can be prevented by pregnant women taking
    folic acid supplements) most common vitamin
    deficiency

31
1.3.7 Metabolic Role of Biomolecules
  • Cyanocobalamin (Vitamin B12)
  • Properties
  • Water-soluble stored in the liver
  • Function
  • Necessary for folic acid use in DNA replication
  • Sources
  • Meat, fish, shellfish, poultry, milk
  • Symptoms of vitamin B12 deficiency
  • Pernicious anaemia (sore tongue, numbness and
    tingling in hands and feet, depression)

32
1.3.7 Metabolic Role of Biomolecules
  • Pantothenic Acid/Pantothenate
  • Properties
  • Water-soluble
  • Functions
  • Coenzyme in carbohydrate, lipid and protein
    metabolism
  • Sources
  • Liver, egg yolk, milk, brussels sprouts
  • Symptoms of Pantothenic Acid deficiency
  • Extremely rare - has only occurred under
    experimental conditions has no specific term

33
1.3.7 Metabolic Role of Biomolecules
  • Biotin
  • Properties
  • Water-soluble
  • Functions
  • Coenzyme in lipid, protein, and DNA synthesis
  • Sources
  • Intestinal bacteria can synthesise biotin, liver,
    meat egg yolk, tomatoes
  • Symptom of Biotin deficiency
  • Dermatitis

34
1.3.7 Metabolic Role of Biomolecules
  • Ascorbic Acid/Ascorbate (Vitamin C)
  • Properties
  • Water-soluble most animals can manufacture their
    own vitamin C - however, primates cannot
  • Functions
  • Formation of collagen - maintenance of skin,
    gums, cartilage, bones, blood vessels and wound
    healing antioxidant facilitates iron absorption
  • Sources
  • Citrus fruits, green peppers, tomatoes
  • Symptoms of vitamin C deficiency
  • Scurvy (tender, sore gums that bleed very easily
    delayed wound healing)

35
Minerals
  • Plants
  • Calcium (Ca)
  • Required for the formation of the middle lamella
    cement that glues neighbouring plant cells
    together
  • Magnesium (Mg)
  • Key component of chlorophyll - lack of magnesium
    leads to a deficiency of chlorophyll and
    reduction in photosynthesis

36
Minerals
  • Animals
  • Calcium (Ca)
  • Required for formation of teeth
  • Growth and maintenance of bone
  • Iron (Fe)
  • Key component of haemoglobin - deficiency of iron
    leads to lack of haemoglobin, resulting in
    anaemia - tiredness and fatigue

37
1.3.8 Water
  • Water is vital to life as we know it
  • It makes up 70 - 95 of cell mass
  • It is an excellent solvent in which all
    biochemical reactions occur
  • It participates in chemical reactions - e.g.
    photosynthesis, respiration and digestion
  • Carries substances around the body of animals and
    plants
  • Carries substances into and out of cells
  • Good absorber of heat energy

38
Anabolism and Catabolism
  • Anabolism is the building up of large
    biomolecules from smaller molecules using energy
  • e.g. photosynthesis and protein synthesis
  • Catabolism is the breaking down of large
    biomolecules into smaller molecules with the
    release of energy
  • e.g. respiration and digestion

39
Mandatory Experimentto conduct qualitative
tests for
  1. Starch
  2. Fat
  3. A Reducing Sugar
  4. A Protein

40
Title (a) to test for starch
  • Apparatus/Chemicals
  • Record the names of everything you use in the
    experiment
  • Method
  • Label test tubes A and B
  • Add 2 ml starch solution to test tube A
  • Add 2 ml of water to test tube B
  • Add a few drops of iodine solution to both test
    tubes and mix
  • Observe any colour changes and repeat experiment
  • Results
  • Test tube A red-yellow ? blue-black
  • Test tube B no colour change

41
Title (b) to test for fats
  • Apparatus/Chemicals
  • Record the names of everything you use in the
    experiment
  • Method
  • Label two pieces of brown paper A and B
  • Drop a few drops of water onto brown paper A
    (control)
  • Rub some butter onto brown paper B (test)
  • Place both pieces of brown paper onto a radiator
    to dry
  • Repeat experiment
  • Results
  • Brown paper A not translucent
  • Brown paper B translucent

42
Title (c) to test for a reducing sugar
  • Apparatus/Chemicals
  • Record the names of everything you use in the
    experiment
  • Method
  • Label test tubes A and B
  • Add 2 ml glucose solution to test tube A
  • Add 2 ml of water to test tube B
  • Add 2 ml of Benedicts reagent to each test tube
    and mix
  • Observe any colour changes and repeat experiment
  • Results
  • Test tube A blue ? brick red
  • Test tube B no colour change

43
Title (d) to test for a protein
  • Apparatus/Chemicals
  • Record the names of everything you use in the
    experiment
  • Method
  • Label test tubes A and B
  • Add 2 ml diluted milk to test tube A
  • Add 2 ml of water to test tube B
  • Add 2 ml of sodium hydroxide to each test tube
  • Add a few drops of copper sulfate solution to
    both test tubes and mix
  • Observe any colour changes and repeat experiment
  • Results
  • Test tube A blue ? violet
  • Test tube B no colour change
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