They Have the Following General Physical Properties;

CARBOHYDRATES

Carbohydrates are made up of carbon, hydrogen and oxygen only. They are classified according to the number of the simple units they contain as;

a)Monosaccharides: (simple sugars)

They have the general formula C6H12O6. Examples are glucose, fructose (found in juicy fruits) and galactose (milk sugar).

They have the following general physical properties;

1. Sweet taste
2. Dissolve in water
3. Can diffuse through a semi permeable membrane

b)Complex sugars

These are sugars composed of two or more monosaccharide molecules. Complex sugars are of two types;

i)Disaccharides

General formula C12H22O11

Formed by the process called condensation. i.e. chemical combination process that results in loss of water molecule.

Example

Glucose+Glucose condensation maltose + water

C6H12O6+ C6H12O6 condensation C12H22O11 + H2O

The disaccharides may be reconverted back to monosaccharides by a process called hydrolysis. Hydrolysis involves the addition of water in a chemical breakdown of larger molecules into smaller forms.

Disaccharides have the following properties

a)Sweet taste

b)Colourless crystalline substance

c)Soluble in water

d)Less diffusion across a semi permeable membrane compared to monosaccharides

ii)Polysaccharides:

These are formed by further condensation of more than two molecules of monosaccharides. They have the general formula (C6H10O5)n where n represents several sugars. Polysaccharides include the following;

a)Starch, stored in plant parts such as cassava, potato, and root tubers.

b)Glycogen: stored form of carbohydrate in animals mainly in muscle and liver

c)Cellulose, found in plant cell walls. It consists of a long chain of glucose.

They have the following general characteristics;

a)Insoluble in water

b)Cannot diffuse across a semi permeable membrane

c)They are not sweet

Functions of carbohydrates

1. Energy production during respiration
2. Formation of structures such as cell walls of plants made of cellulose
3. Cellulose is used in the manufacture of papers, synthetic fibers, films and explosives.

VITAMINS

Vitamins are organic constituents of food that are required in small amounts for a variety of metabolic processes. They often form part of enzymes.

Vitamins are of two groups, i.e. water soluble and fat soluble vitamins. Fat soluble vitamins include A, D, E, and K. water soluble vitamins include B and C

VITAMIN / FOOD SOURCES / FUNCTIONS / DEFICIENCY AND SYMPTOMS.
A
RETINAL / Animal fat and oils, milk, liver, green vegetables, carrots, green paper. / Normal growth.
Keeps skin and eyes healthy.
Increases resistance to disease. / Poor night vision [xeropthalamia] or night blindness.
Poor growth.
Reduced resistance to diseases.
B1
THIAMINE / Yeast,egg,liver,pulses,
Tomatoes, uunpolihsed cereals. / As a coenzyme in cell respiration for the normal functioning of the heart and nerveous system / Disease of the muscles, nerves and heart.
Loss of appetite.
Circulatory failure.
Paralysis.
Digestive trouble.
Wasting away of the muscles.
Poor assimilation loss of weight.
B2
RIBOFLAVIN / Meat, milk, other as for B1 / For cell respiration
For skin health / Slow growth
Skin diseases
Sore mouth.
PP NIACINICOTINIC ACID / Meat, fish, wheat, eggs, liver, green, vegetatables. / For cell respiration / PELLAGRA
-A skin disease
-Mental disorder
-Abdominal pains
-Diarrhea
-Pigmentation in exposed areas of the chest
C
Ascorbic acid / Fresh citrus fruits, green vegetables, Irish potatoes / -Increased resistance to disease
-Formation of collagen
-Healing of wounds / SCURVY
-Pains and swelling of the joints and gums,
-Loosening of teeth, bleeding of the gums, skin and mucous membranes
-Poor wound healing
-General weakness
D
Calciferol / Milk, eggs, fish, liver, oil and butter.
Skin of man in sunlight / Hardening of bones and teeth / RICKETS
(faulty bone formation in children)
Teeth diseases (dental caries)
E
(Tocopherol) / Vegetable oil, eggs, liver / Promotes fertility
(in rats) / Sterility in animals e.g. rats
K
Phyloquinone / Green vegetables, tomatoes and liver / Clotting of blood / Delayed clotting of blood

Test for vitamin C

Requirements

DCPIP (dichlorophenol indophenol)

Test tube

Dropper

Solution of ascorbic acid

Procedure

Place 1 cc of DCPIP solution to a test tube

Add the solution of ascorbic acid to DCPIP drop by drop stiring gently. Do not shake

Add until the colour of DCPIP just disappears

Observation

Blue colour of DCPIP disappears leaving a colourless solution

Note: if solution has much vitamin C then very few drops will decolourise DCPIP

Mineral elements

These are in organic food constituents required by the body in small amounts but their deficiency affects the functioning of the body leading to a deficiency disease or symptom

Mineral elements can be grouped into

-Essential mineral elements; i.e. those required in large amounts and include; Na, P, K, Ca and Fe

-Non essential mineral elements; these are required in small amounts and include; Zn, Mo, Co, B and Mn. They are also called trace elements.

Table 3.4 Giving facts about some of the mineral elements required by man

MINERAL ELEMENT / FOOD SOURCES / IMPORTANCE / DEFFICIENCY
IRON / Beef, liver, kidney, green vegetables, G nuts, cocoa, beans, eggs. / Constituent of haemoglobin / Reduced red blood cell count and oxygen transport resulting in ANAEMIA
CALCIUM / Vegetables, fish, milk, bread, eggs. / Constituent of bones and teeth which it is responsible for hardening
For muscle contraction.
For clotting of blood.
Activator of enzymes. / RICKETS
DELAYED MUSCLE CONTRACTION
PHOSPHOROUS / Most foods [dairy products, meat,fish, poultry, nuts.] / Formation of ATP.
FORMATION OF BONES AND TEETHS
Constituent of cell membranes / Not likely to be deffiecient since it is present in most foods especially protein
IODINE / Sea fish, iodised salts. / Constituent of the hormone thyroxine. / GOITRE [swelling of the thyroid glands ]
SODIUM / Common salt. / Transmission of nerve impulses
Muscle contraction / MUSCLE CRUMP [ie sharp pains in muscles]
FLUORINE / Added to drinking water. / Constituent of bones and teeth.
Prevents dental carries / Weak teeth [in children].

PROTEINS

Proteins are body building foods. They are made up of carbon, hydrogen, nitrogen, oxygen and sometimes sulphur and phosphorus. Compared with most other organic molecules, protein molecules are huge and therefore can not pass through semi-permeable membrane.

Proteins are made up of small unit molecules called amino acids.

The nature of protein is determined by the types of amino acids it is made of.

Amino acids have the general formula

H

RCCOOHNH2 _ amino group

NH2

There are about 20 amino acids that make up proteins in living organisms.

TYPES OF AMINO ACIDS

There are two types of amino acids;

1. Essential amino acids.

These are amino acids that can not be synthesized by the body and have to be supplied in the diet. Examples are valin, arginine, leusin, lysine, phenydalanine etc. there are 10 essential amino acids.

1. Non essential amino acids.

These are the amino acids which can be synthesized by the body and therefore need not to be available in the died.exaples include glycine, alanine, asparticacid, serine, praline etc.

There are also 10 non essential amino acids.

CLASSIFICATION OF PROTEINS

Proteins can be classified into two,

1. First class proteins. These are the proteins that contains all the essential amino acids eg soyabeans, and most animal proteins.
2. Second class proteins. These are proteins that lack one or more of the essential amino acids. They include mostly plant proteins and a few animal pro

FORMATION OF PROTEINS

Proteins are made up of many amino acid units joined together through peptide bonds. When two amino acids are joined together a dipeptide is formed. The chemical process involved is called condensation in which water is formed or lost.

When many amino acids are joined together a polypeptide chain is formed. The nature of a particular protein depends on the types and sequence of amino acids from which it is made.

PROPERTIES OF PROTEINS

1. Dissolve with difficulty in water to form colloidal solution (sticky like glue)

2. They have large molecules and so cannot pass through cell membranes.

3. Proteins coagulate when boiled. This is what happens when the egg albumen is boiled.

FUNCTIONS OF PROTEINS

1. Vital for the formation of new cells and replacement of old ones hence growth.
2. They help in maintaining the composition of protoplasm.
3. They are used in the formation of various structures in the body eg keratin in the hair, nails, hooves, horns, feathers etc.
4. They are important in the formation of enzymes, which speed up chemical reactions in organisms..
5. They form antibodies which defend the body against diseases.
6. Coordination of activities in the body as a hormone constituent.
7. Proteins may be used for respiration in circumstances where carbohydrates and lipids are not present.

Deficiency of proteins causes a disease called kwashiorkor. Occurs normally in children between ages of 6 months and 4 years because of the high energy requirement and growth after weaning.

TEST FOR PROTEINS

Procedure / Observation / conclusion
Biuret’s test
To 2cc of solution containing proteins in a test tube, add 2cc of a NaoH followed by 1-2 drops of CUSO4 / The blue solution turned to purple solution. / Proteins present

NB if the solution remains blue, then proteins are absent.

Record all observations as seen with all states. E.g blue solution turns to colourless solution

2 Millon’s test
To 2cc of a protein in a test tube, add 1cc of millon’s reagent and heat or boil. / A white pp forms which coagulates on heating and turns red or pink. / Protein present.

If the solution remains colorless then proteins are absent.

TESTING FOR VITAMIN C (ASCORBIC ACID)

Test reagent

DCPIP (Blue)

Procedure.

• Place 2cc of DCPIP in a test tube.
• Then add the specimen solution containing vitamin c drop by drop.

Observation

• Presence of vitamin c is when solution turns colourless.
• Absence of vitamin c is when the solution retains the blue colour of DCPIP.

Testing for different carbohydrates

Starch

procedure / observation / conclusion
To 2 cc of solution containing starch in test tube, add 2-3 drops of iodine / Colourless solution turns to Blue black solution / Starch present

Iodine is brown in colour and if after adding to a solution and it remains brown then the conclusion is- starch is absent

Reducing sugars

Procedure / Observation / Conclusion
To 2 cc of solution of the reducing sugar in the test tube add equal volume of benedicts solution and shake well, heat to boil for 1 minute / The solution turns from blue to green to yellow and finally to orange ppt / Reducing sugars present
OR
To 2 cc of a solution of reducing sugars in test tube, add 1 cc of felling’s solution and shake well. Heat to boil / The colourless solution turns from blue soln to green to yellow and finally to orange ppt / Reducing sugars present

Note:

Felling’s and benedicts solutions are blue in colour and when added to test solution, the solution immediately takes up the blue colour of the reagent.

Any change in initial blue colour of mixture i.e. green indicates presence of reducing sugars in small quantities

If there is no change in blue colour of mixture, then reducing sugars are absent.

Non reducing sugars

Note: there is no direct test for non reducing sugars. They are first hydrolyzed (converted) to reducing sugars by boiling with dilute hydrochloric acid.

Procedure / Observation / Conclusion
To 2 cc of solution containing the non-reducing sugar in a test tube add 1 cc of dilute HCL and boil for one minute. Cool the test tube in cold water.
Carefully add solution of sodium hydroxide to neutralize the acid
Add 2 cc of Benedict’s solution and shake well. Heat while shaking until it boils / The solution turns from blue solution to green to yellow and finally forms an orange or brown ppt / Reducing sugars present

Note: the roles of HCL and NaOH

Water.

Water is made up of two elements; Hydrogen and Oxygen

Functions of water

1. Being a good solvent enables it to transport nutrients
2. Regulates body temperature especially during sweating and transpiration
3. Helps in elimination of nitrogenous wastes of metabolism such as urea and ammonia
4. It is a raw material for photosynthesis
5. It offers turgidity in hydrostatic skeleton hence support in organisms.

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