 to maintain life  to supply energy & give warmth ◦ carbohydrates ◦ fats ◦ proteins  for growth and repair ◦ Proteins  keep healthy & help to fight against disease

 elements : C, H, O ◦ ratio of H : O = 2 : 1  monosaccharides ◦ C 6 H 12 O 6 ◦ all are sweet & soluble in water ◦ all are Reducing Sugars ◦ include Glucose, Fructose & Galactose

u disaccharides (from 2 monosaccharides) – C 12 H 22 O 11 – all are sweet & soluble in water – Maltose ( 2 glucose molecules ) – Sucrose ( glucose + fructose) (non-reducing sugar) – Lactose ( glucose + galactose) Carbohydrates surcose surcose

 polysaccharides (NOT sugar)  for energy storage ◦ starch (store in plants) glycogen (store in animals)  Hydrolysis: Polysaccharide + H 2 O  Disaccharides + H 2 O  Monosaccharides

u main source of energy u cellulose: - fibrous material of Plant Cell Wall - dietary fibre: stimulates Peristalsis u excess carbohydrates - stored as glycogen in liver & muscle - stored as fats under skin Functions of Carbohydrates

Test for Reducing Sugars (Benedict’s Test)

Is there any colour change in tubes A and B ? Ans: Only the mixture in tube A has a colour change. AB glucose solution + Benedict’s solution distilled water + Benedict’s solution water bath

What is the sequence of change when there is a colour change ? Ans: The blue solution changes first to green, then to a yellow coloration and eventually a brick-red precipitate is produced. AB glucose solution + Benedict’s solution distilled water + Benedict’s solution water bath

Test for Starch (Iodine Test)

What is the final colour in tube A ? Ans: The solution in tube A changes from brown to blue black. iodine solution starch solution distilled water A B

What is the purpose of setting up tube B ? Ans: To act as a control. iodine solution starch solution distilled water A B

 elements: C, H, O, N, sometimes S, P  components : amino acids forms dipeptides & polypeptides  Condensation: Amino acids –H 2 O  Dipeptides –H 2 O  Polypeptide

 are compounds of carbon, hydrogen, oxygen, nitrogen and sometimes sulphur, phosphorus  amino acids: ◦ unit of proteins ◦ about 20 different types ◦ essential and non-essential types

H 2 N amino group COOH carboxyl group C R H

hydrolysiscondensation

H2NH2NC R1R1 H C O OH H N H C H R2 COOH H2N C R1R1 H O H C H R2R2 COOH C---N H2O

u cannot be stored - excess proteins are deaminated by liver ~ to Urea which will be excreted away by Kidney ~ to Carbohydrates (Glycogen) which will be stored in Liver Proteins

 for growth and repair of body cells (as structural components (cell membrane and cytoplasm) of cells)  to produce hormones and enzymes and antibodies  to give energy  for making Haemoglobin in blood  for making Antibodies

Kwashiorkor

Test for Proteins (Biuret Test)

egg white solution 1 cm 3 NaOH solution Put CuSO 2 solution drop by drop, and shake the mixture after addition of each drop Positive result: purple colour

What colour changes in tubes A and B ? Ans: Mixture in tube A changes from blue to purple while mixture in tube B remains blue without any change. copper sulphate solution egg white + sodium hydroxide solution water + sodium hydroxide solution A B

 elements : C, H, O  components of 1 lipid molecule: 1 glycerol + 3 fatty acids  insoluble in water  soluble in organic solvent

Functions of Lipids u give energy u component of cell membrane u form fatty tissues under skin > to store energy > acts as insulator to keep warm u to transport fat-soluble vitamins (A, D, E, K)

Spot Test for Fat

Which substance, oil or water, leaves a permanent translucent spot on the filter paper ? Ans: Oil.

Emulsion Test for Fat

Which test tube has an emulsion formed ? Ans: Test tube A. 2 drops of cooking oil 2 cm 3 of alcohol 2 cm 3 of distilled water after shaking to form a clear solution shake and then allow to stand emulsion oil water shake and then allow to stand shaking 2 drops of cooking oil 2 cm 3 of distilled water A B

What happens to the other tube ? Ans: The mixture separates into two layers because fats do not dissolve in water. 2 drops of cooking oil 2 cm 3 of alcohol 2 cm 3 of distilled water after shaking to form a clear solution shake and then allow to stand emulsion oil water shake and then allow to stand shaking 2 drops of cooking oil 2 cm 3 of distilled water A B

 no energy value  essential for small amount to maintain good health  water soluble vitamins ( B, C )  fat soluble vitamins ( A, D, E, K ) u excessive of some vitamins may be harmful

Vitamin A  formed in the body from Carrotene (a yellow pigment in carrots)  destroyed at high temperature  essential for forming visual purple (maintain dim light vision)

Vitamin C  Destroyed after prolonged cooking  Necessary for wounds-healing Vitamin D  Formed in Skin from Ultraviolet Light  Help to regulate Ca & P metabolism

Detection of Vitamin C in Lemon Juice by using DCPIP

What colour change has occurred ? Ans: The blue DCPIP decolourizes. syringe lemon juice DCPIP solution

What conclusion can you draw ? Ans: Lemon juice contains vitamin C which decolourizes blue DCPIP. syringe lemon juice DCPIP solution

VitaminSources Deficiency Disease A Egg yolk, milk, cheese, carrot, green vegetables Night blindness C Fresh fruits & green vegetables Scurvy D Cod liver oil & egg yolk Rickets

SubstancesTest Original Colour Positive Result Reducing Sugar Benedict’sBlueOrange ppt StarchIodineBrownBlue-black ProteinBiuretBlue Violet Fats/OilsSpot --- Translucent spot Fats/OilsEmulsionClearMilky emulsion Vitamin CDCPIPBlue Colourless (decolourize)

Mineral Salts u regulate body metabolism u essential for healthy growth u necessary for construction of certain tissues u needed in small amount u include Ca, S, K, Na, Mg, Fe, I

Mineral(s) SourcesFunctions Deficiency Disease Calcium & Phosphorus Cheese, milk, vegetables Making bones & teeth Important for blood clotting & muscle contraction Rickets Iron Liver, eggs, beef, green leafy vegetables Structural component of Haemoglobin Anaemia

Dietary Fibre u mainly cellulose u indigestible material for human u give bulk to food & stimulate peristalsis  prevent Constipation u lack of dietary fibre: Large Intestine Cancer u sources: wholemeal cereals, unpolished rice, fresh vegetables & fruits

 have enough food to supply enough ◦ energy  carbohydrates, fats, proteins ◦ body building materials  proteins ◦ substances to maintain health  vitamins, minerals, water & dietary fibres  malnutrition : not having balanced diets for long time

 Calorimeter is used to measure the amount of energy contained in a particular type of food  Carbohydrate (17kJ/g)  Protein (18kJ/g)  Fat (39kJ/g)

 Sex  Age  Occupation  Physical Activities  Stage of individual (pregnancy, breast-feeding)

Measure the Energy Value of Food

boiling tube water burning peanut thermometer Explain why the energy value of the peanut is lower than those from standard tables. Ans: Because there are a number of inaccuracies associated with this method due to incomplete combustion and heat loss.

Basal Metabolic Rate (BMR) u minimum amount of energy needed by an individual lying awake in bed to maintain breathing, body temperature & heartbeat u varies from one individual to another u daily energy requirement > basal metabolic rate

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