Applications of Biotechnology: One Mark Questions, Book Back Answers and Notes

About Applications of Biotechnology

Medium ~90 min study

Once scientists learned to cut, join and copy DNA, they could make bacteria produce human proteins, detect a virus from a few copies of its genes and create a sheep from a single body cell. This chapter looks at what those tools are actually used for.

It starts with medicines: human insulin made in E. coli, interferons and recombinant vaccines. It then moves to treating the cause of genetic disease, through gene therapy and stem cell therapy. Next come diagnostic methods, PCR and ELISA, which pick up infections before symptoms appear. The chapter then covers whole organisms: transgenic animals and the cloning of Dolly. It ends with the questions that come with this power: bioethics, biopiracy and the committees in India that regulate genetically modified organisms.

Book back questions often ask how insulin chains A and B are produced and joined, the difference between somatic and germline gene therapy, types of stem cells by potency, the three steps of PCR, and the names and roles of GEAC and RCGM. Learn the steps of each technique in order; a jumbled sequence is an easy trap in an MCQ.

What you'll learn

• Explain how recombinant human insulin and recombinant vaccines are produced.
• Distinguish somatic cell gene therapy from germline gene therapy.
• Classify stem cells by their origin and potency.
• Explain how PCR and ELISA help detect diseases early.
• Describe how transgenic animals are produced and what they are used for.
• Outline the steps of somatic cell nuclear transfer used to clone Dolly.
• Discuss the ethical issues, biosafety guidelines and regulatory bodies in biotechnology.

Before you start

• DNA structure, replication and the central dogma.
• Basic principles of genetic engineering and cloning vectors.

Applications of Biotechnology explained

Biotechnology in Medicine, Animals and Law

Biotechnology in Medicine

Recombinant DNA technology lets us make human proteins in large amounts. For human insulin, the DNA sequences coding for chain A and chain B are inserted separately into plasmids of Escherichia coli. The bacteria make the two chains, which are extracted, purified and joined by disulphide bonds to give active insulin, sold as Humulin. Earlier, insulin came from the pancreas of cattle and pigs and caused allergic reactions in some patients. Transgenic animals can also act as sources: Rosie, a transgenic cow, produced milk containing human alpha-lactalbumin. Interferons made by recombinant methods are used against viral infections and some cancers.

Gene Therapy and Stem Cell Therapy

Gene therapy treats a genetic disorder by correcting the faulty gene. In gene augmentation therapy, a normal copy of the gene is added to make up for a missing function. In gene inhibition therapy, an antisense gene is introduced to block a dominant defective gene. The first clinical gene therapy, in 1990, treated a four-year-old girl with adenosine deaminase (ADA) deficiency. Her lymphocytes were grown outside the body, a functional ADA cDNA was introduced using a retroviral vector, and the cells were returned to her. Because lymphocytes do not live forever, the treatment must be repeated; a permanent cure would need the gene to be introduced into cells at an early embryonic stage. Stem cell therapy uses the ability of embryonic and adult stem cells to divide and form other cell types to repair damaged tissues.

Molecular Diagnosis

Conventional tests such as microscopy or serum analysis often miss an infection in its early stages, when there are very few pathogens. Molecular methods are far more sensitive. PCR (polymerase chain reaction) makes millions of copies of a small piece of pathogen DNA or RNA, so it can detect HIV in suspected AIDS patients or mutations in genetic disorders such as sickle cell anaemia. ELISA (enzyme-linked immunosorbent assay) detects antigens or antibodies through a specific antigen-antibody reaction and uses an enzyme colour change instead of radioactivity.

Transgenic Animals and Cloning

A transgenic animal carries a foreign gene in its genome that is passed on to its offspring. Such animals are used to study human diseases, to test the safety of vaccines and drugs, and to produce useful proteins, for example in their milk. In 1997, Ian Wilmut and Campbell produced Dolly the sheep by somatic cell nuclear transfer. The nucleus of an udder (mammary gland) cell was fused with an egg cell whose own nucleus had been removed, and the embryo was placed in a surrogate mother. No fertilization was involved, so Dolly was genetically identical to the sheep that gave the udder cell.

Ethical Issues, Regulation and Biosafety

Genetic manipulation raises ethical and safety questions. Bioethics deals with right and wrong in medicine and research. Biopiracy is the use of biological resources or traditional knowledge from a country without permission or fair payment. In India, the Review Committee on Genetic Manipulation (RCGM), under the Department of Biotechnology, monitors research on genetically engineered organisms. The Genetic Engineering Appraisal Committee (GEAC), under the Ministry of Environment, Forest and Climate Change, approves their large-scale use and release into the environment.

Common mistakes to avoid

• Confusing somatic and germline gene therapy. Somatic therapy changes body cells only and is not inherited; germline therapy changes gametes or early embryos and is passed on.
• Calling embryonic stem cells totipotent. They are pluripotent: they form cells of all three germ layers but not a whole organism with its placenta. Only the zygote and its earliest cells are totipotent.
• Thinking PCR detects proteins. PCR amplifies DNA (or RNA after copying it to DNA); ELISA is the test that detects antigens or antibodies.
• Getting the PCR steps out of order. Each cycle is denaturation, then annealing of primers, then extension, each at its own temperature.
• Calling cloning a form of sexual reproduction. Cloning by nuclear transfer involves no fertilization and produces a genetically identical copy.

Test yourself on these with the practice test, then check the worked reasoning in the solved MCQs.

Frequently asked questions

What is recombinant insulin and how is it made?

Recombinant insulin is human insulin made by bacteria. The DNA sequences for insulin chains A and B are inserted into plasmids of Escherichia coli. The bacteria are grown in fermenters and produce the two chains, which are extracted, purified and joined by disulphide bonds to form active insulin. It is sold under the name Humulin.

How does gene therapy treat genetic diseases?

Gene therapy puts a working gene into a patient's cells so they can make the protein that is missing or faulty. The gene is usually carried by a viral vector, as in the ADA deficiency case, where a retrovirus carried ADA cDNA into the patient's lymphocytes. In gene inhibition therapy, an antisense gene is introduced to switch off a dominant defective gene.

What is the difference between pluripotent and multipotent stem cells?

Pluripotent stem cells, such as embryonic stem cells, can form cells of all three germ layers and so almost any cell type in the body. Multipotent stem cells are limited to a family of related cells. Blood-forming stem cells in the bone marrow, for example, give rise only to the different blood cells.

Why is PCR preferred over conventional diagnostic tests?

Conventional tests usually work only after the pathogen has multiplied or symptoms have appeared. PCR copies even a few molecules of a pathogen's DNA or RNA millions of times, so it can confirm an infection very early. This matters for diseases like HIV, where early detection changes treatment.

How was Dolly the sheep cloned?

Ian Wilmut and Campbell used somatic cell nuclear transfer in 1997. They took cells from the udder of an adult ewe and grew them in a low-nutrient medium so they stopped dividing. The nucleus of such a cell was fused with an egg cell from another ewe whose nucleus had been removed. The embryo was grown for a few days and placed in the uterus of a surrogate ewe, which gave birth to Dolly.

What does GEAC do?

The Genetic Engineering Appraisal Committee is the statutory body under India's Ministry of Environment, Forest and Climate Change. It reviews and approves the large-scale use, import, transport and release into the environment of genetically engineered organisms and their products, to protect human health and the environment.