Biotechnology: Class 10 Biology

Key points

Biotechnology is the use of living organisms, or their parts, to make useful products or to improve plants and animals. Traditional biotechnology is very old and includes making bread, yoghurt, cheese and vinegar. Modern biotechnology uses genetic engineering, tissue culture and cloning.

Fermentation is the breakdown of sugars by microorganisms in the absence of oxygen to give useful products. Yeast ferments sugar to ethanol and carbon dioxide, which is the basis of brewing and bread making. The carbon dioxide makes dough rise. Lactic acid bacteria change milk sugar (lactose) to lactic acid, which turns milk into yoghurt and cheese.

Large scale fermentation is carried out in a fermenter, a big closed vessel where temperature, pH, oxygen supply and nutrients are controlled. Industries use it to make antibiotics such as penicillin, citric acid, vitamins, enzymes and alcohol.

Genetic engineering is the deliberate change of the genetic material of an organism by adding, removing or changing genes. It allows a gene from one species to be placed in another. An organism that carries a foreign gene is called transgenic. The DNA formed by joining pieces from two sources is called recombinant DNA.

Main steps in making a recombinant DNA product, such as human insulin in bacteria:

• The human gene for insulin is cut out of human DNA using restriction enzymes, which cut at specific sites.
• A plasmid, a small circular piece of bacterial DNA, is cut with the same enzyme.
• The insulin gene is joined into the plasmid by the enzyme DNA ligase, which forms recombinant DNA.
• The plasmid is put back into a bacterium such as E. coli.
• The bacteria multiply rapidly in a fermenter and make insulin, which is separated and purified.

Before genetic engineering, insulin for diabetics came from the pancreas of pigs and cattle, which could cause allergic reactions and was limited in supply. Bacteria now make human insulin in large amounts, and it is cheap and safe. Human growth hormone and some vaccines, such as the one for hepatitis B, are also made by this method.

Tissue culture is the growth of cells, tissues or organs on a sterile nutrient medium in the laboratory. Small pieces of a plant are placed on agar with nutrients and hormones, and they grow into new plants. It is used to produce many disease free plants quickly, such as bananas, orchids and sugarcane, and to save rare species.

Cloning produces organisms that are genetically identical to one another. A natural example is a plant grown from a cutting. In animal cloning, as in Dolly the sheep in 1996, the nucleus of a body cell from one sheep is placed into an egg cell whose own nucleus was removed. The egg develops into an embryo in the womb of a surrogate mother, and the lamb is a copy of the nucleus donor.

Single cell protein (SCP) is protein obtained from microorganisms such as algae, yeast, bacteria and fungi. These organisms grow very fast on cheap wastes and are rich in protein, so SCP can be used as a food supplement or animal feed. It may help to reduce food shortage.

Biogas is a mixture of mainly methane and carbon dioxide made when bacteria break down animal dung and plant wastes in the absence of air in a digester. It is used for cooking and lighting in many villages of Pakistan, and the leftover slurry is a good fertiliser. It is a renewable and clean fuel.

Applications of biotechnology:

• Medicine: insulin, vaccines, antibiotics, interferon and DNA tests for diseases.
• Agriculture: crops that resist insects or herbicides, such as Bt cotton, which carries a bacterial gene for an insecticidal protein, and crops with improved nutrition.
• Industry and environment: enzymes in detergents, treatment of sewage and bacteria that clean oil spills.
• Forensics: DNA fingerprinting to identify criminals and establish family relationship.

Biotechnology also raises concerns. Genetically modified crops may harm other species or spread genes to wild plants. There are worries about food safety, patent rights and the ethics of cloning. So the use of this technology is governed by safety rules and public discussion.

Study tip: Learn the steps of insulin production as a numbered list in the correct order, with the name of each enzyme and what it does. Give one clear example for each application, since examples earn marks in medium length answers.

Definitions and flashcards

Say the meaning first, then open the card to check.

Short questions with model answers

These are the kind of questions asked for 2, 3 and 5 marks. Try each one before opening the answer.

Common mistakes

• Saying that fermentation needs oxygen. It takes place without oxygen.
• Mixing up restriction enzymes, which cut DNA, with ligase, which joins DNA.
• Thinking that a cloned animal is a copy of the surrogate mother. It is a copy of the nucleus donor.
• Writing that bacteria cannot make human proteins. After genetic engineering they can.
• Calling the plasmid the main chromosome of the bacterium.

Practise this chapter

Practice questions and timed test Printable worksheet