Topic 3 chapter 4 part 1 nutrients - full
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Topic 3: Chapter 4
Nutrients Nutrients – – Part 1Part 1
The The need need for for
food food + +
CarboCarbohydrathydrat
eses
Chemicals and Reactions that take place in the
cell.• Living organisms contains huge amount of
Macromolecules (large molecules)
• Chemical activities that take place in a cell is known as metabolism.
• Metabolic reactions are categorized as anabolic reactions and catabolic reactions.
Anabolic & Catabolic Reactions
• Anabolic reactions build up large molecules from simple molecules.
• Catabolic reactions break down larger molecules into smaller molecules.
Illustration of Anabolic & Catabolic Reactions
H20 Nitrate Phosphate
Sunlight CO2
Carbohydrates(e.g. Glucose)
Photosynthesis
Illustration of Anabolic & Catabolic Reactions
Nitrate Phosphate
Lipids
Carbohydrates(e.g. Glucose)
Protein
Eat
Digestion
Absorption
Why do organisms need food?
1) To provide energy for the vital activities of the body via respiration.
Physical movement, Digestion, Excretion, etc.
2) To synthesize new protoplasm – for growth & repair, & for reproduction.
3) To maintain good health – prevent deficiency disease.
Vit. C, Calcium, etc.
Nutrients• Chemical substances in food that nourish the body.• They provide energy & raw materials needed by
the body.
(A) Organic Nutrients(A) Organic Nutrients(Contains Carbon)(Contains Carbon)
(A) Organic Nutrients(A) Organic Nutrients(Contains Carbon)(Contains Carbon)
(B) Inorganic Nutrients(B) Inorganic Nutrients(does not contain Carbon)(does not contain Carbon)
(B) Inorganic Nutrients(B) Inorganic Nutrients(does not contain Carbon)(does not contain Carbon)
1)1) CarbohydratesCarbohydrates2)2) FatsFats3)3) ProteinsProteins4)4) VitaminsVitamins5)5) Dietary FibreDietary Fibre
1)1) WaterWater2)2) Mineral SaltsMineral Salts
A(1): Carbohydrates
• Organic compounds made up of the elements carbon (C), hydrogen (H) & oxygen (O).
• The hydrogen & oxygen atoms are present in the ratio 2:1.
• Generalized formula: CnH2mOm.
A(1): Functions of Carbohydrates
a) as a substrate for respiration provide energy for cell activities
b) to form supporting structures e.g. plant cell walls
c) to be converted to other organic compounds such as amino acids and fats
d) for the formation of nucleic acid e.g. DNA
e) to synthesize lubricants e.g. mucus – Carbo + Protein)
f) to produce the nectar in some flowers
A(1): Sources of Carbohydrates
•Broken down quickly to provide energy for the body
• Found naturally in food (Fruits, Milk, etc.)
• Found in processed or refined food ( Candy, Syrup, etc.)
•Lack Vitamins, Minerals & Fibres
•Made of sugar molecules strung together in long complex chains
• Majority of carbohydrates are from complex carbohydrates and naturally occurring sugars.
•Provides Vitamins, Minerals & Fibres
A(1): Groups of Carbohydrates
CarbohydratesCarbohydrates
Polysaccharides (complex carbohydrates)
Polysaccharides (complex carbohydrates)
Disaccharides (double sugars)
Disaccharides (double sugars)
Monosaccharides(single sugars)
Monosaccharides(single sugars)
e.g. glucose fructose, galactose
e.g. glucose fructose, galactose
e.g. starch, glycogen, cellulose
e.g. starch, glycogen, cellulose
e.g. Sucrose, Maltose, Lactose
e.g. Sucrose, Maltose, Lactose
• Simple sugars, sweet
• Smallest basic unit.
• ALL with general formula C6H12O6.
- But differ in arrangement of atoms in molecules.
Monosaccharides(single sugars)
Monosaccharides(single sugars)
Disaccharides(double sugars)
Disaccharides(double sugars)
• Simple sugars, sweet
• Formed when 2 monosaccharides are joined together by condensation.
• ALL with general formula C12H22O11.
Condensation
• Chemical reaction in which
• A water molecule is needed
• to break up a complex molecule into smaller molecules
• Chemical reaction in which
• A water molecule is needed
• to break up a complex molecule into smaller molecules
• Chemical reaction in which
• 2 simple molecules are joined together to form a larger molecule
• with the removal of water
• Chemical reaction in which
• 2 simple molecules are joined together to form a larger molecule
• with the removal of water
Hydrolysis
Condensation: Formation of
LactoseLactose
• occurs naturally in milk (milk sugar). • broken down by the enzyme “lactase” during
digestion to yield glucose and galactose by hydrolysis• When milk sours, bacteria converts lactose to lactic
acid
Condensation: Formation ofMaltase
Maltase
• Malt Sugar• Important component in the process of fermenting
barley that can be used for brewing beer.• broken down by the enzyme “maltase” during
digestion to yield 2 glucose molecules by hydrolysis
Condensation: Formation ofSucrose
Sucrose
• occurs naturally in sugarcane (cane sugar), sweet fruits, honey and certain storage roots (e.g. carrots).
• Not found in mammals
Hydrolysis: Breaking down ofSucrose
Sucrose
+
enzyme
glucose fructosesucrose water
+
• broken down by the enzyme “sucrase” / “invertase” during digestion to yield glucose and fructose by hydrolysis
Polysaccharides(complex carbohydrates)
Polysaccharides(complex carbohydrates)
• Consists of many monosaccharide molecules joined together by condensation.
• Starch, Glucogen and Cellulose are complex carbohydrates which are made up of numerous glucose molecules condensed together.
starch
Polysaccharides(complex carbohydrates)
Polysaccharides(complex carbohydrates)
Starch Starch
• Long straight or branched chains of glucose molecules
• Made and stored in plants but not in animals
starch
Polysaccharides(complex carbohydrates)
Polysaccharides(complex carbohydrates)
Cellulose Cellulose
• Long straight chains of glucose molecules
• But different linkages from starch.
• Main part of plant cell wall
• Forms fibre in the diet of mammals
starch
Polysaccharides(complex carbohydrates)
Polysaccharides(complex carbohydrates)
Glycogen Glycogen
• Highly branched chains of glucose
• Made and stored in animals and fungi but not in plants
Storage Glucose
• Starch
• Stored in leaves, tubers and roots
Plants
Animals• Gycogen
• Stored mainly in liver and muscles
Glycogen and Starch as storage materials
• Insoluble in water
do not change the water potential in cells
• Large molecules
Unable to diffuse through cell membranes
• Easily hydrolysed to glucose when needed
e.g for tissue respiration
• Compact shapes which occupies less space.
Hydrolysis and Condensation
maltase maltase maltase maltase
Starch (in plants)Starch (in plants)
MaltoseMaltose
GlucoseGlucose
Hydrolysis in the mouth
Hydrolysis in the guts by enzyme maltase
Condensation in the liver
Glycogen (in animals)Glycogen (in animals)
Consumed and undergoes Digestion
Digestion
Glucogenesis
Food Test (1) Food Test (1) Test for Starch – Iodine Test for Starch – Iodine
TestTest
Procedure:• Add 1-3 drops of iodine solution onto any
substance.
Results:• If starch is present, the iodine solution
changes from yellowish brown to blue-black colour.
Food Test (2) Food Test (2) Test for Reducing Sugars – Test for Reducing Sugars –
Benedict’s TestBenedict’s TestReducing Sugars: Reducing Sugars:
Glucose, Fructose, Maltose, Lactose
Procedure:Procedure:
1. Add 2 cm3 of Benedict’s solution to equal volume of test solution.
2. Mix the solutions by shaking.
3. Heat the mixture in a boiling water-bath for 5 minutes.
4. Prepare a control using distilled water instead of the test solution Benedict’s solution
Food Test (2) Food Test (2) Test for Reducing Sugars – Test for Reducing Sugars –
Benedict’s TestBenedict’s TestResults
Colour change Amount of reducing sugar present
blue to green mixture trace amount
blue to yellow / orange precipitate moderate amount
blue to brick-red precipitate large amount
Food Test (2) Food Test (2) Test for Reducing Sugars – Test for Reducing Sugars –
Benedict’s TestBenedict’s TestResults
Positive Benedict’s test Negative Benedict’s test
Brick Red Precipitate
Blue solution
Topic 3: Chapter 4
Nutrients Nutrients – – Part 2Part 2
FFatatss
LipidsLipids
SteroidsSteroids
ExamplesExamples
Phospholipids Phospholipids FatsFats
For storage of energy
For storage of energy e.g. cholesterole.g. cholesterol
Makes up the Plasma
membrane
Makes up the Plasma
membrane
A(2): FATS• Organic compounds made up of the elements
carbon (C), hydrogen (H) & oxygen (O).
• but unlike carbohydrates, they contain much less oxygen in proportion to hydrogen. (E.g. Beef Fat: Tristearin – C57H110O6)
• No General formula for fats
• Fats fall under the category of LIPIDS
A(2): Composition of a Fat Molecule
• A fat molecule is made up of four parts:
- 1 molecule of glycerol
- 3 fatty acid chains
Glycerol
Fatty Acids
A(2): Breaking down fatsHydrolysi
sHydrolysi
s
• The breaking down of 1 fat molecule involves the addition of 3 water molecules to form 1 glycerol and 3 fatty acid molecules IN THE PRESENCE OF AN ENZYME (Lipase)
A(2): Forming fatsCondensatio
nCondensatio
n
• Conversely, a fat molecule can be formed by adding 3 fatty acid molecules to 1 glycerol molecule, removing 3 molecules of water
A(2): Groups of Fats
FatsFats
Unsaturated FatsUnsaturated FatsSaturated FatsSaturated Fats
A(2):
• Found mostly in animals• Fatty acids are straight chains
• Most are solid at room temperature (e.g butter)
• Cholesterol usually found with polysaturated fats Increases risk of Coronary Heart Diseases & Gall stone formation
Saturated FatsSaturated Fats
• Found mostly in vegetables (except Coconut and Palm Oil)
• Fatty acids are bent in some places
• Most are liquid at room temperature (e.g Olive Oil)
• Fatty acid chains contains double bonds and are able to take in 1 or more pairs of H-atoms
• Hydrogenation of unsaturated fats Trans-fat
A(1): Unsaturated FatsUnsaturated Fats
Saturated Fats Unsaturated Fats
Butter Cheese Fatty Meats Coconut oil Palm oil
Peanuts Walnuts Olives Corn Oil Soybean Most fishes (e.g Salmon,
mackerel, tuna, sardines)
A(2): Sources of Fats
A(1): Functions Fatsa) as a source and store of energy
b) Insulating material (Prevents excessive heat loss)
e.g layer of blubber beneath the skin of whales
c) Solvent for fat-soluble substances
some vitamins and vital substances (e.g hormones)
d) Essential part of the protoplasm e.g cell membrane (Phospholipds and cholesterol)
e) A way to reduce water loss from the skin surface
Food Test (3) Food Test (3) Test for Fats – Alcohol Test for Fats – Alcohol
Emulsion TestEmulsion Test
Procedure: Add 2 cm3 of ethanol to the test solution and
shake the mixture thoroughly for 5 minutes. Observe for changes.
Add 2 cm3 of water to the mixture and shake the mixture. Observe for changes.
Liquid Food
Food Test (3) Food Test (3) Test for Fats – Alcohol Test for Fats – Alcohol
Emulsion TestEmulsion Test
Procedure: Cut the sample into small pieces and place
them in a test tube. Add 2cm3 of ethanol and shake thoroughly. Allow the solid particles to settle. Decant the
ethanol into another test tube containing 2cm3 of water. Make observations.
Solid Food
Food Test (3) Food Test (3) Test for Fats – Alcohol Test for Fats – Alcohol
Emulsion TestEmulsion Test
Results: A white emulsion is formed if fats is present
white emulsio
n
Topic 3: Chapter 4
Nutrients Nutrients – – Part 3Part 3
ProProteintein
ss
Where are Proteins found in our body?
A(3): Proteins• Are very large complex organic moluecules
containing carbon (C), hydrogen (H), oxygen (O) and nitrogen (N). Sometimes, Sulfur (S) and Phosphorus (P)
• E.g. Insulin: C254H317O75N65S6
• Made up of basic small units called amino acids
ProteinsProteins
Acidic Group-COOH
Acidic Group-COOH
Formed from
Formed from
R-Groups:May contain:
Sulphur, Acidic groups,
amino groups, and/orHydroxyl groups
R-Groups:May contain:
Sulphur, Acidic groups,
amino groups, and/orHydroxyl groups
Amino Group-NH2
Amino Group-NH2
Amino AcidsNH2-CHR-COOH
Amino AcidsNH2-CHR-COOH
A(3): General Structure of an amino acid
• A fat molecule is made up of four parts:
- 1 Amino Acid group (-NH2)
- 1 Acidic Group (-COOH)
- 1 Side Chain (denoted by R)
Can be:•Sulfur (S)•Acidic groups (-COOH)•Amino groups (--NH2) and/or•Hydroxyl groups (-OH)
A(3): Why is there a need for so many different R-groups?
• The R-Group determines the type of amino acid formed.
• There are 20 naturally occuring amino acid:• Examples –
• Leucine, Valine, Glutamine:
• 8 Essential a.a: Cannot be synthesized by the body. Must be obtained through the diet
• 12 Non-Essential a.a: Can be synthesized by the body
A(3): Synthesis of Proteins
• The bond between 2 amino acids is called: Peptide Bond• Many amino acids link together by peptide bonds to form a
polypeptide chain / peptone
Condensation
Condensation
amino acids polypeptides Protein molecule
A(3): Synthesis of ProteinsPrimary / Secondary
StructurePrimary / Secondary
StructureTertiary StructureTertiary Structure
Amino acids are linked by
peptide bonds to form
polypeptide chains
Amino acids are linked by
peptide bonds to form
polypeptide chains
Polypeptide chains coil and
fold around each other to form a
3-d structure held by weak
H-bonds
Polypeptide chains coil and
fold around each other to form a
3-d structure held by weak
H-bonds
Different proteins have a different sequence of A.A
A.A sequence determines the bonds formed and the structure of the protein.
Different proteins with different structures perform different functions.
Weak H-bonds can be easily broken by:
• Heat• Chemicals like Acid and AlkalisProtein loses its structure
and function (is
DENATURED)
Different proteins have a different sequence of A.A
A.A sequence determines the bonds formed and the structure of the protein.
Different proteins with different structures perform different functions.
Weak H-bonds can be easily broken by:
• Heat• Chemicals like Acid and AlkalisProtein loses its structure
and function (is
DENATURED)
Structure VS FunctionStructure VS Function
A(3): Digestion of Proteins
polypeptides
amino acids
protein
hydrolysis (digestion)
hydrolysis (digestion)
Protein molecules are too large to pass through the cell membranes
Smaller and simpler A.A molecules are soluble in water and can pass through the cell membrane into the cells to synthesize new proteins
Animals Plants
Milk Eggs Seafood Chicken Lean beef
Nuts Soy bean Grains Vegetables
A(3): Sources of Proteins
A(1): Functions Proteins
a) Formation of new protoplasm
for growth & repair of worn-out body parts/ cells
b) Synthesis of enzymes and hormones e.g digestive enzymes and insulin / sex and
growth hormones
c) Formation of antibodies to combat diseases
d) Can be source of energy
Food Test (4) Food Test (4) Test for Proteins – Biuret Test for Proteins – Biuret
TestTest
Procedure: Add 1 cm3 of sodium hydroxide solution to the
2 cm3 of test solution. Shake thoroughly. Add 1% copper (II) sulphate solution, drop by
drop, shaking after each drop.
ALTERNATIVELY Add 2cm3 of test solution to an equal volume
of Biuret solution. Shake well and allow the mixture to stand for 5 minutes.
Food Test (4) Food Test (4) Test for Proteins – Biuret Test for Proteins – Biuret
TestTest
Results: A violet colouration is
formed if proteins is present
positive test for protein
positive test for protein