Experiments on Biochemistry | Chemistry

Are you researching experiments on biochemistry ? You are in the right place. The below mentioned article includes a collection of fifteen experiments on biochemistry: 1. Lipids 2. Enzymes 3. Cellulose 4. Cutin 5. Hemicellulose 6. Latex 7. Phenols 8. Lignin 9. Suberin 10. Pectin 11. Chitin 12. Tannin 13. Saponification Number 14. Iodine Number 15. Detection of Ca and P in Milk.

Contents:

1. Experiment on Lipids
2. Experiment on Enzymes
3. Experiment on Cellulose
4. Experiment on Cutin
5. Experiment on Hemicellulose
6. Experiment on Latex
7. Experiment on Phenols
8. Experiment on Lignin
9. Experiment on Suberin
10. Experiment on Pectin
11. Experiment on Chitin
12. Experiment on Tannin
13. Experiment on Saponification Number
14. Experiment on Iodine Number
15. Experiment on Detection of Ca and P in Milk

1. Experiment on Lipids (Fats or Oils):

Aim of the Experiment:

To perform colour test for lipids (fats or oils).

What are lipids (Fats or oils)?

Substances like esters which are soluble in organic solvents are known as lipids. They can be tested by adding a few drops of Sudan III. The formation of red colour indicates the presence of lipids.

Requirements:

Almond seeds, soya bean or groundnut, sudanIII, 1% osmic acid, glycerine, slides, 50% alcohol.

Method and observations:

1. Cut thin sections of the provided material (i.e., almond seeds, soya bean or groundnut, etc.) and place them in Sudan III. Wait for 10 minutes.

2. Wash the sections first with 50% alcohol and then thoroughly with water. Mount in glycerine and observe under microscope.

It is observed that oil drops take a red stain.

3. Now add a few drops of 1% osmic acid on the material.

Result:

This develops the black colour and gives a confirmation of the presence of fats or oils.

To observe the specificity, thermo ability and colloidal nature of enzymes.

Take one tablet of Taka diastase and dissolve it in 50 ml of distilled water. The resulted solution is known as enzyme solution, and can be used for observing these properties.

Test tubes, starch, castor oil, enzyme solution, Sudan III, iodine.

1. Take two test-tubes.

2. In one, take 1 ml of 1% starch solution and in the other test tube take 1 ml of castor oil.

3. Add 2 ml of enzyme solution in both the test- tubes.

4. Keep both the test tubes for 5 minutes in test-tube stand.

5. In the test tube containing starch add a few drops of iodine. But there is no test for starch, showing the fact that starch has been hydrolysed by the enzyme.

6. In the test tube containing castor oil add Sudan III. There is no change in the oil. It is because of the fact that the enzyme used is specific for starch.

3. Experiment on Cellulose:

Aim of the Experiment:

To test the presence of cellulose in the cotton threads or filter paper and to reveal the biological significance and chemical nature of cellulose.

What is cellulose?

It is a carbohydrate polymer made of glucose molecules. It occurs in the micro fibrils in the walls of most plant cells. Its formula is (C₆H₁₀O₅)n. The chief sources of cellulose are wood, cotton and other fibrous materials. Cellulose are the chief raw materials for the manufacture of paper and rayon.

Requirements:

Filter paper (or cotton fibers), iodine solution, sulphuric acid, water, slides, coverslips and microscope.

Method and observations:

1. Torn the paper or given material so much so that the fibers are exposed.

2. Place the fibers on a slide in a drop of water and add a few drops of iodine solution.

Observe the fibers under microscope. Fiber- thickenings turn brown.

3. Diffuse a drop of sulphuric acid (75%) onto the fibers.

Result:

Change of colour in the fibre thickenings from brown to blue confirms the presence of cellulose in the given material.

Biological importance:

Cell wall of plants is mainly composed of cellulose (C₆H₁₀O₅)n, which is a polysaccharide carbohydrate. It is more complex than starch. However, it is insoluble and indigestible, and, therefore, is seldom used as food. It is made up of several glucose molecules. It forms an important raw materials in paper making.

4. Experiment on Cutin:

Aim of the Experiment:

To test the presence of cutin in the given material.

What is cutin?

It is a substance made of fatty acid products. Cutin is impermeable to water and found in the cuticle of plants.

Requirements:

Nerium or Ficus leaf, potassium hydroxide, slides, coverslips, microscope, water.

Method:

1. Cut the thin sections of the provided material, place them in water and treat with potassium hydroxide solution.

2. Observe the sections under microscope.

Result:

Depositions on the epidermis turn yellow in colour. This confirms the presence of cutin.

5. Experiment on Hemicellulose:

Aim of the Experiment:

To test the presence of hemicellulose in soya bean seeds.

What is hemicellulose?

It is a heterogeneous group of long-chain polysaccharides distinct from cellulose. The basic units of hemicelluloses are arabinose, xylose, mannose or galactose. They form the part of the cell wall of plants, mainly in lignified tissue.

Requirements:

Soya bean seeds, slide, coverslips, microscope, iodine, glycerine, water, razor.

Method:

1. Cut a thin section of the soya bean seed with a razor, put it in water and observe under microscope.

2. Treat the section with iodine for a few minutes, mount in glycerine and again observe under microscope.

Result:

The colour of section turns blue, and this confirms the presence of hemicellulose.

6. Experiment on Latex:

Aim of the Experiment:

To test the presence of latex in the given material.

What is latex?

It is a coloured, milky or sticky liquid, produced by specialized cells of some plants. It consists of a watery solution containing many different substances including terpenoids which form rubber, and alkaloids such as the alkaloids of opium, sugar, starch, etc.

Requirements:

Latex from latex-yielding plants of Asclepiadaceae (e.g., Calotropis), Euphorbiaceae (e.g., Ricinuscommunis) or Apocynaceae (e.g., Nerium, Thevetia, etc.,), conc. sulphuric acid, sucrose, test tubes, water.

Method:

1. Prepare an alcoholic extract of latex in a test tube, and pour in it an equal amount of sucrose and sulphuric acid.

Result:

Pinkish or purplish colour is formed, and this confirms the presence of latex.

7. Experiment on Phenols:

Aim of the Experiment:

To test the presence of phenols in the plant tissues by ferric chloride test.

What are phenols?

Phenols are the organic compounds possessing an —OH group attached directly to the aromatic ring. The term is also used for the simplest compounds of this class, C₆H₅OH. They may be monohydric or polyhydric. Phenols and their derivatives occur in several microorganisms, pteridophytes, gymnosperms and angiosperms.

Phenolic compounds speed up the rate of mutation in plants and hence they are mutagenic in nature. Some of the common phenolic compounds are carbolic acid, 2-methyl phenol, 4-nitro phenol, salicylic acid.

Requirements:

Rose flowers, distilled water, filter paper, ferric chloride solution, test tubes, beaker, mortar, and pestle.

Method:

1. Collect some petals of rose flowers and crush them thoroughly with the help of a mortar and pestle.

2. Add some distilled water in the crushed petals to make an aqueous solution. Filter the solution through filter paper and collect the filterate in the test tube.

3. Add a few drops of neutral ferric chloride solution in the filterate.

Observations and results:

Purple colour appears in the filterate. This is due to the presence of phenolic compounds in the rose petals which turn purple after the addition of a few drops of neutral ferric chloride solution.

8. Experiment on Lignin:

Aim of the Experiment:

To test the presence of lignin in the given material.

What is lignin?

It is a complex aromatic compound, deposited in the cellulose cell walls of the sclerenchyma and xylem of several plants during the process of secondary thickening. Wood of most plants is made of lignin.

Requirements:

Match sticks (or match shavings or wood shavings), 1% alcoholic solution of phloroglucin, coverslips, slides, HCl (25%), 1% aqueous neutral potassium permanganate, HCl (2%), water and sodium bicarbonate (or ammonium hydroxide).

Test No. 1:

1. Prepare thin sections or slices of the given material and place them in 1% alcoholic solution of phloroglucin.

2. Cover the material with coverslips and diffuse HCl (25%) along the edges of the coverslip. Wait for a few minutes.

Result:

Lignified walls of the material take a reddish violet colour. This confirms the presence of lignin.

Test No. 2:

1. Place the sections or slices of the material in aqueous neutral potassium permanganate (1%) and wait for 10-20 minutes.

2. Wash the material with HCl (2%).

3. Wash it now thoroughly with water.

4. Now add a few drops of sodium bicarbonate (or ammonium hydroxide).

Result:

Lignified walls develop deep red colour. This confirms the presence of lignin.

9. Experiment on Suberin:

Aim of the Experiment:

To test the presence of suberin in the given plant material.

What is suberin?

It is a mixture of substances formed from fatty acids. It is found in cork cell walls. It stops water from passing through the cork.

Requirements:

Natural cork (or bottle cork), alcohol (50%), Sudan IV (alcoholic), glycerine, water, slides, coverslips.

Method:

1. Take some bottle cork or any other provided material and cut its thin slices or sections.

2. Put the sections in Sudan IV and wait for about 20 minutes.

3. Wash with alcohol (50%) to remove excess of stain.

4. Now wash with water, mount in glycerine and observe under the microscope.

Result:

Red stain in the suberised portion confirms the presence of suberin.

10. Experiment on Pectin:

Aim of the Experiment:

To test the presence of pectin in the given material.

What are pectins?

Pectins are acidic polysaccharides found in young cell walls, especially in the middle lamella and primary walls of vascular plants. Chemically, they are calcium-magnesium salts of poly-galacturonic acid, partially joined to methanol residues by ether linkage. They are soluble in water, and are used in jam making.

Requirements:

Razor, endosperm of Nasturtium seeds, Ruthenium-red stain prepared in water, glycerine, watch glass, slides, coverslips, brush, microscope.

Method:

1. Soak the Nasturtium seeds for some time in water and then cut thin cross sections of the endosperm of these soaked seeds with a sharp razor.

2. Put these sections in the dilute aqueous solutions of Ruthenium-red in watch glass and wait for about 15-20 minutes.

3. Wash thoroughly with water to remove excess of stain.

4. Select a thin stained section, put it on a slide, mount in glycerine and observe under microscope.

Result:

Deep red stain in the middle lamella confirms the presence of pectin in the material.

11. Experiment on Chitin:

Aim of the Experiment:

To demonstrate the presence of chitin in the mycelial mat of the given fungus.

What is chitin?

Chitin is a nitrogen-containing polysaccharide with the formula (C₈H₁₃N₅)n. It is the main substance in the cell walls of most fungi. It also occurs as skeletal material in many invertebrates, particularly the cuticle of the members of Arthropoda.

Requirements:

Autoclave, mycelial mat of a fungus, slides, coverslips, IKI solution prepared in 1 % H₂SO₄, dropper, brush.

Method:

1. Take the mycelial mat of a suitable fungus grown in liquid culture and autoclave it.

2. Wash the mycelial mat, put it on a slide, mount it in a few drops of IKI solution prepared in 1% H₂SO₄ and observe under a microscope.

Result:

Violet-brown colour of the cell walls of the mycelium of the fungus indicates the presence of chitin in the material.

12. Experiment on Tannin:

Aim of the Experiment:

To test the presence of tannin in the given material.

What are tannins?

Tannins are a group of astringent substances found commonly in the outer tissue of many plants. They are dissolved in the cell sap and occur commonly in the bark of trees, unripe fruits, leaves and galls. These are complex organic compounds containing phenols, hydroxy acids and glucosides. Tannins are widely used in the tanning of leather and also in the production of ink.

Requirements:

Razor, bark of Ber (Zizyphusmauritiana) or Jamun (Eugenia jambolana) or any other plant, di-meth-oxy-benz-aldehyde (DMB)-reagent, ethanol, HCl, incubator, slides, cover slips, dropper, microscope.

Method:

1. With the help of a good razor cut sections of the bark of the given plant material and place them in DMB-reagent (1% 2, 4-Dimethoxy Benz-aldehyde in 90% ethanol and 18% HCl).

2. Incubate the sections of the material at 24°C for about 5 minutes and mount on a slide in a few drops of DMB-reagent.

Result:

Development of purplish red colour indicates the presence of tannins in the material.

13. Experiment on Saponification Number:

What is saponification and saponification number?

When the fats are mixed intimately and heated with an alcoholic solution of strong alkali, such as sodium or potassium hydroxide, the glyceride molecules are split and the ultimate products are glycerol and sodium or potassium salts of the fatty acids. This process is known as soap production or saponification. The number of milligrams of KOH required to saponify 1gm of fat completely is called saponification number.

Aim of the Experiment:

To determine ‘Saponification Number’ of the given oil.

Requirements:

Pipettes (2 of 5 ml and one each of 25 ml and 50 ml), burette (1), flasks (3), water bath (1), oil or fat, hydrochloric or sulphuric acid of known strength, 0.1% phenolphthalein and 0.5 N KOH (alcoholic).

Method:

1. Take two flasks.

2. In one flask take 50 ml of alcoholic KOH and in the another pre-weighed flask take one ml of the oil and add 51 ml of alcoholic KOH of known strength.

3. Label both the flasks (The first one will function as control).

4. Boil for about half an hour on a water bath. After removing the flasks from water bath, let them be cool.

5. To each flask add one ml of 0.1% phenolphthalein.The colour of the solution becomes pink.

6. Titrate the solution of both the flasks with sulphuric or hydrochloric acid of known strength and note the reading.

7. Calculate the saponification number with the help of the following formula:

Y= 28(A – B)/X

where,

Y= Saponification number.

A = Reading of control (volume of acid required for titration of KOH).

B = Reading of KOH and oil (volume of acid required for titration of KOH and oil).

X= Weight of oil.

28 gm. KNH = 1 ml 0.05 N acid.

14. Experiment on Iodine Number:

What is iodine number?

The iodine number is defined as the number of grams of iodine absorbed by 100 gm. of a fat.

Aim of the Experiment:

To determine the iodine number of the given oil.

Requirements:

Burette (1), pipettes 25 ml and 10 ml, conical flasks (4), fat or oil, pyridine sulphate-di-bromide reagent, 7.5% potassium iodide, 0.1 N sodium thiosulphate, 0.5% starch suspension and chloroform.

Preparation of stock solution:

A given amount of a fat or oil is dissolved in a given amount of solvent, e.g., take 2 gm. of oil or fat and dissolve it in 100 ml of chloroform. This will serve as stock solution for the determination of iodine number.

Preparation of pyridine sulphate-di-bromide reagent:

This reagent is prepared by mixing 5.4 ml of conc. H₂SO₄ with 20 ml of glacial acetic acid (Note that this is an exothermic reaction and will evolve heat. So be careful in pouring H₂SO₄ into acetic acid). To this is added 8.1 ml of pyridine dissolved in 20 ml of glacial acetic acid.

This solution is added very carefully to a solution of bromine (2.5 ml of bromine in 20 c.c. of glacial acetic acid). The whole mixture is diluted with acetic acid to make 1 litre of reagent. This is then kept in well-stoppered bottle in a warm place where it will keep fit for a fortnight or so.

Preparation of 0.5% starch suspension:

Dissolve 0.5 gm. of starch in 100 c.c. of distilled water. Boil it, and use when it is cool.

Method:

1. Take 10 ml of stock solution of fat or oil.

2. Add 25 ml of pyridine sulphate-di-bromide reagent and wait for five minutes.

3. Determine the residual bromine by adding 10 ml of potassium iodide solution. The equal amount of iodine will be liberated by residual bromine and can be determined by titration with 0.1N sodium thiosulphate.

4. 2 ml of starch suspension is also added before titration. The starch will act as an indicator and a blue colour is obtained.

5. On the other hand, a total amount of bromine is determined by titrating 25 ml of pyridine sulphate-di-bromide reagent against 0.1 N sodium thio-sulphate-solution.

6. Complete disappearance of blue colour will indicate the end point.

Calculations:

Suppose the volume of sodium thiosulphate required for total bromine added is ‘O’ mL

The volume (sodium thiosulphate) required for residual bromine is ‘P’ ml.

So, the volume of sodium thiosulphate required

= (O-P) ml.

Because 1 ml of 0.1 N sodium thiosulphate

= 0.0127 gm. of iodine.

So, (O – P) ml 0.1 N sodium thiosulphate

= 0.0127 x (O – P) gm. of iodine

Because 10 ml of chloroform solution of fat requires = 0.0127 × (O – P)gm. of iodine.

So, 100 ml. chloroform solution of fat requires

= 0.0127 x(0-P) 10 gm. of iodine.

It indicates that 2 gm. of fat requires = 0.0127 × (O-P) gm. of iodine.

So, 100 gm. of fat requires

= 0.0127 × (O – P) × 100/2gm of iodine

So, Iodine Number = 6.35 × (O -P)

If the reading of control = 13.2 c.c.

and reading with fat = 3 c.c.

So, (0-P) = 13.2-3= 10.2c.c.

Iodine Number = 6.35 × 10.2 = 65.405.

15. Experiment on Detection of Ca and P in Milk:

Aim of the Experiment:

To detect Ca and P in milk and to determine the specific gravity of milk.

Requirements:

Boiling tubes, small test tubes, beakers, spirit lamp, filter paper, funnel, lactometer, pH paper, acetic acid, nitric acid, ammonia, milk, ammonium molybdate and ammonium oxalate.

Principle:

If the milk is treated with 1% acetic acid, Ca and P are filtered, and fat and casein remain of the filter paper.

So, the first part of the experiment is the preparation of fat and protein-free filterate which can be prepared in the following manner:

Take 10-15 ml of milk in a boiling tube and add 1 % acetic acid till a white precipitate appears. This white precipitate is due to casein and fat. Its pH can be tested by pH paper which comes to 4.6. Filter it with the help of filter paper and funnel. This filtrate contains Ca and P.

Test for Phosphate:

Method:

Take about 5 ml of casein and fat-free filtrate in a test tube and add about 1 ml of HNO₃ (Conc.) and 3 mlofammonium molybdate.

Result. Appearance of yellow colour or precipitate confirms the presence of phosphate.

Test for Calcium:

Method:

1. Take about 5 ml of casein and fat-free filtrate.

2. Add little amount of ammonia to make it alkaline.

3. Now add ammonium oxalate.

Result:

Appearance of white precipitate shows the presence of calcium in the milk.

Observations:

Tabulate your observations and results in the form of following table:

Result:

Milk contains Ca and P.

Specific Gravity:

It can be determined by a simple apparatus of glass called lactometer. Lower the conical part of this apparatus, filled with mercury. Due to the presence of mercury in the lower part, it floats in the liquids in a straight position. Upper part of lactometer consists of a straight tube containing a scale.