Applications of biotechnology: Questions and Answers (Evaluation)

Evaluation

1. The first clinical gene therapy was done for the treatment of

a) AIDS

c) Cancer

d) Cystic fibrosis

e) SCID

Answer: c) Cystic fibrosis

2. Dolly, the sheep was obtained by a technique known as

a) Cloning by gene transfer

b) Cloning without the help of gametes

c) Cloning by tissue culture of somatic cells

d) Cloning by nuclear transfer

Answer: d) Cloning by nuclear transfer

3. The genetic defect adenosine deaminase deficiency may be cured permanently by

a) Enzyme replacement therapy

b) periodic infusion of genetically engineered lymphocytes having ADA cDNA

c) administering adenosine deaminase activators

d) introducing bone marrow cells producing ADA into embryo at an early stage of development.

Answer: a) Enzyme replacement therapy

0. GEAC stands for

a) Genome Engineering Action Committee

b) Ground Environment Action Committee

c) Genetic Engineering Approval Committee

d) Genetic and Environment Approval Committee

4. How many amino acids are arranged in the two chains of Insulin?

a) Chain A has 12 and Chain B has 13

b) Chain A has 21 and Chain B has 30 amino acids

c) Chain A has 20 and chain B has 30 amino acids

d) Chain A has 12 and chain B has 20 amino acids.

Answer: b) Chain A has 21 and Chain B has 30 amino acids

5. PCR proceeds in three distinct steps governed by temperature, they are in order of

a) Denaturation, Annealing, Synthesis

b) Synthesis, Annealing, Denaturation

c) Annealing, Synthesis, Denaturation

d) Denaturation, Synthesis, Annealing

Answer: a) Denaturation, Annealing, Synthesis

6. Which one of the following statements is true regarding DNA polymerase used in PCR?

a) It is used to ligate introduced DNA in recipient cells

b) It serves as a selectable marker

c) It is isolated from a Virus

d) It remains active at a high temperature.

Answer: d) It remains active at a high temperature

7. ELISA is mainly used for

a) Detection of mutations

b) Detection of pathogens

c) Selecting animals having desired traits

d) Selecting plants having desired traits

Answer: b) Detection of pathogens

8. Transgenic animals are those which have

a) Foreign DNA in some of their cells

b) Foreign DNA in all their cells

c) Foreign RNA in some of their cells

d) Foreign RNA in all their cells

Answer: b) Foreign DNA in all their cells

9. Recombinant Factor VIII is produced in the ________ cells of the Chinese Hamster

a) Liver cells

b) blood cells

c) ovarian cells

d) brain cells.

Answer: c) ovarian cells

10.Vaccines that use components of a pathogenic organism rather than the whole organism are called

a) Subunit recombinant vaccines

b) attenuated recombinant vaccines

c) DNA vaccines

d) conventional vaccines.

Answer: a) Subunit recombinant vaccines

11. Mention the number of primers required in each cycle of PCR. Write the role of primers and DNA polymerase in PCR. Name the source organism of the DNA polymerase used in PCR.

• Number of primers required for each cycle of PCR is 2. They are forward and reverse primers.

• Primer : A primer is a short strand of RNA or DNA that serves as starting point for DNA synthesis.

• DNA poymerase : The DNA polymerase used in PCR is Taq polymerase. This enzyme is able to withstand the high temperature and makes the new strands of DNA using existing strands as templates.

• DNA polymerase : Taq polymerase is obtained from thermophilic bacterium Thermus aquaticus.

12. How is the amplification of a gene sample of interest carried out using PCR?

• DNA is heated to separate two strands this is called deneturation. It is done at 95° C

• Primer is added and temperature is reduced to 75° C. This is called anneling. This will allow Taq polymerase to extend each primer.

• Free nucleotides are added along with DNA polymerase.

• The new strand of each double stranded DNA (genes) extends to a variable distance downstream. 

13. What is genetically engineered Insulin?

• The insulin which are obtained from recombinant DNA technology are called genetically engineered Insulin.

• The approval to use recombinant insulin for diabetes mellitus was given in 1982.

• This is also called humulin.

14. Explain how “Rosie” is different from a normal cow.

• Rosie is a transgenic cow.

• It was considered different from a normal cow as it produced human protein enriched milk.

• The milk contained human alpha - lactalbumin

• It was a nutritionally a more balanced product for human babies than normal cow.

15. How was Insulin obtained before the advent of rDNA technology? What were the problems encountered?

• In the early years, insulin isolated and purified from the pancreas of pigs and cows.

• It was used to treat diabetic patients

Problem of using animal insulin

• It resulted in the occurrence of allergic reaction in some diabetic patients due to minor variation in their structure.

16. ELISA is a technique based on the principles of antigen-antibody reactions. Can this technique be used in the molecular diagnosis of a genetic disorder such as Phenylketonuria?

• Yes, phenylketonuria can be diagnosed by ELISA

• ELISA test used antibodies against phenylalanine which are then bound by another antibody which binds the original antibody as an antigen.

17. Gene therapy is an attempt to correct a Genetic defect by providing a normal gene into the individual. By this the function can be restored. An alternate method would be to provide gene product known as enzyme replacement therapy, which would also restore the function. Which in your opinion is a better option? Give reasons for your answer.

• Gene therapy is better than the enzyme replacement therapy.

• Because gene therapy permanently cure the genetic disease caused by single gene mutation.

• But enzyme replacement therapy manage the disease and their benefit is temporary.

18. What are transgenic animals? Give examples.

Animals that are produced by DNA manipulations are called transgenic animals or genetically engineered or genetically modified organisms.

Example: Transgenic mice, rat, rabbit, pig, cow, sheep and fish etc.

19. If a person thinks he is infected with HIV, due to unprotected sex, and goes for a blood test. Do you think a test such as ELISA will help? If so why? If not, why?

• Yes, ELISA is used to diagnose AIDS.

• ELISA is a tool for determining serum antibody concentrations.

• It is also used for detecting the presence of specific antigens and hormones such as human chorionic gonadotropins. 

20. Explain how ADA deficiency can be corrected?

It can be corrected by

1) Bone marrow transplantation:

• In some children ADA deficiency could be cured by bone marrow transplantation.

• Defective immune cells could be replaced with healthy immune cells from a donor.

• In some patients it can be treated by enzyme replacement therapy in which functional ADA is injected into the patient.

2) Gene therapy :

• The lymphocytes from the blood of the patient are removed and grown in a nutrient culture medium.

• The functional ADA cDNA encoding this enzyme is introduced into the lymphocytes using retrovirus.

• These genetically engineered lymphocytes are subsequently returned to the patient.

• The disease could be cured permanently if the ADA gene is introduced into the bonemarrow cells of early embryo.

21. What are DNA vaccines?

• DNA vaccine consists of a gene encoding an antigenic protein

• It is inserted into a plasmid and then incorporated into the cells in a target animal.

• DNA instructs the cells to make antigenic molecules which are displayed on its surfaces.

• This would evoke an antibody response to the free floating antigen secreted by the cells.

22. Differentiate between Somatic cell gene therapy and germline gene therapy.

Somatic cell gene therapy

1. Therapeutic genes transferred into the somatic cells

2. Introduction of genes into bone marrow cells, blood cells, skin cells etc

3. Will not be inherited in later generations

Germ line gene therapy

1. Therapeutic genes transferred into the germ cells.

2. Genes introduced into eggs and sperms

3. heritable and passed on to later generations

Five Mark Questions

23. What are stem cells? Explain its role in the field of medicine.

Stem Cells:

Stem cells are undifferentiated cells found in most of the multi cellular animals. These cells maintain their undifferentiated state even after undergoing numerous mitotic divisions.

Role in the field of medicine :

i) Stem cells research has the potential to revolutionize the future of medicine with the ability to regenerate damaged and diseased organs.

ii) Stem cells are capable of self renewal and exhibit cellular potency

iii) Stem cells can differentiate into all types of cells that are derived from any of the three germ layers ectoderm, endoderm and mesoderm. 

iv) In mammals there are two main types of stem cells -enbryonic stem cells (ES cells) and adult stem cells.

Embryonic stem cells :

v) ES cells are pluripotent and can produced the three primary germ layers ectoderm, mesoderm and endoderm.

vi) Embryonic stem cells are multipotent stem cells that can differentiate into a number of types of cells.

ES cells are isolated from the epiblast tissue of the inner cell mass of a blastocyst.

When stimulated ES can develop into more than 200 cell types of the adult body.

ES cells are immortal.

Adult stem cells:

vii) Adult stem cells are found in various tissues of children as well as adults.

An adult stem cell or somatic stem cell can divide and create another cell similar to it. Most of the adult stem cells are multipotent and can act as a repair system of the body, replenishing adult tissues.

The red bone marrow is a rich source of adult stem cells.

viii) The most important and potential application of human stem cells is the generation of cells and tissues that could be used for cell based therapies.

Human stem cells could be used to test new drugs.

24. One of the applications of biotechnology is ‘gene therapy” to treat a person born with a hereditary disease.

i. What does “gene therapy” mean?

ii. Name the hereditary disease for which the first clinical gene therapy was used.

iii. Mention the steps involved in gene therapy to treat this disease.

i) Gene therapy :

It involves the transfer of a normal gene into a person's cells that caries one or more mutant alleles.

ii) The first clinical gene therapy :

The first clinical gene therapy was given in 1990 by French Anderson to four year old girl with adenosine deaminase (ADA) deficiency.

iii) Steps involved in gene therapy to treat ADA deficiency :

• Bacterium carrying plasmid with cloned normal human ADA gene is selected.

• Genetically disabled retrovirus is selected.

• Cloned ADA gene is incorporated into virus.

• Retrovirus infects T cells and Transfer of ADA gene into cells.

• Cells are grown in culture to ensure ADA gene is active.

• Genetically altered cells are reimplanted to produce ADA.

25. PCR is a useful tool for early diagnosis of an Infectious disease. Elaborate.

• The specificity and sensitivity of PCR is useful for the diagnosis and treatment of viral and bacterial diseases.

• The concept behind PCR based diagnosis of infectious disease is simple. If the pathogen is present in clinical specimen, it's DNA will be present.

• It's DNA has unique sequences that can be detected by PCR. Often using clinical specimens in the PCR mixture.

• PCR is a valuable tool for diagnosis and monitoring retroviral intentions like tuberculosis.

• Several virally induced cancers like cervical cancer caused by papilla virus also can be detected by PCR.

26. What are recombinant vaccines?. Explain the types.

Recombinant vaccines :

The recombinant vaccines are generally of uniform quality and produce less side effects as compared to the vaccines produced by conventional methods.

Different types of recombinant vaccines include subunit recombinant vaccines attenuated recombinant vaccines and DNA vaccines.

i) Subunit recombinant vaccines

• Vaccines that use component of a pathogenic organism rather than the whole organism are called sub unit vaccines; recombinant DNA technology is very suited for developing new subunit vaccines.

• It includes components like proteins, peptides and DNAs of pathogenic organisms.

• The advantages of these vaccines include their purity in preparation, stability and safe use.

ii) Attenuated recombinant vaccines

• This includes genetically modified pathogenic organisms that are made non pathogenic and are used as vaccines.

• It is now possible to genetically engineer the organisms (bacteria or viruses) and use them as live vaccines and such vaccines are reffered as attenuated recombinant vaccines.

27. Explain why cloning of Dolly, the sheep was such a major scientific breakthrough?

• Dolly, a Finn Dorset sheep, was bom on July 5^th 1996 at Roslin Institute of Edinburgh Scotland.

• It was developed by nuclear transfer.

• It is considered as one of the most significant scientific breakthrough ever.

• Dolly's birth and subsequent survival proved that adult cells can regrow themselves into a new being.

• This knowledge changed what scientists thought was possible and opened up a lot of possibilities in biology and medicine.

28. Mention the advantages and disadvantages of cloning.

Advantages :

i) Offers benefits for clinical trials and medical research. It can help in the production of proteins and drugs is the field of medicine.

ii) It helps stem cell research

iii) Animal cloning could help to save endangered species.

Disadvantages :

i) Animal and human activists see it as a threat is biodiversity which will have as impact on populations and the ecosystem.

ii) The process is tedious and very expensive

iii) It can cause animals to suffer.

iv) Surrogates were manifesting adverse out comes. Cloned animals have high mortality rate.

v) It might compromise human health through consumption of cloned animal meat.

vi) Cloned animals aged faster than normal animals and are less healthy than the parent organisms as discovered in Dolly.

vii) Cloning can lead to occurrence of genetic disorders in animals.

viii) More than 90% of cloning attempts fail-to produce a viable offspring.

29. Explain how recombinant Insulin can be produced.

• The donor DNA (Insulin producing gene) is obtained from human pancreatic cells.

• A vector called plasmid is isolated and cut into fragments by using restriction endonuclease enzyme.

• Donor and plasmid DNA is joined together by ligase enzyme as a result recombinant DNA is obtained.

• Recombinant DNA is introduced into a suitable bacterium. Now this is called as recombinant bacterium.

• Recombinant bacteria multiplying and producing human insulin in fermentation tank.

• From the fermentation tank insulin is extracted and purified.

30. Explain the steps involved in the production of recombinant hGH.

i) human growth hormones somatostatin and somatotropin are peptide homones secreted by the pituitary gland.

ii) Deficiency of human growth hormone causes dwarfism, which could be treated by injecting hGH extracted from the human pituitary glands.

iii) The gene for hGH is isolated from the human pituitary gland cells. The isolated gene is inserted into a plasmid vector and then is transferred into E.coli.

iv) The recombinant E.coli then starts producing human growth hormone. The recombinant E.coli are isolated from the culture and mass production of hGH is carried out by fermentation technology.

v) A recombinant form of human growth hormone called somatropin is used as a drug to treat growth disorders in children.

Extra One mark Questions and Answers

1. Genetic engineering has been successfully used for producing

a) Transgenic mice for testing safety of polio vaccine before used in humans.

b) Transgenic models for studying new treatments for certain cardiac diseases.

c) Transgenic cow Rosie which produces high fat milk for making ghee.

d) Animals like bulls for farm work as they have super power.

2. Some of the characteristics of Bt cotton are

a) Long fibre and resistance to aphids

b) Medium yield, long fibre and resistance to beetle pests.

c) High yields and production of toxic protein crystals which kill dipteran pests.

d) High yield and resistance to bollworms

3. Bacillus thuringiensis forms protein crystals which contain insecticidal protein. This protein

a) Binds with epithelia cells of midgut of the insect pest ultimately killing it.

b) Is coded by several genes including the gene cry.

c) Is activated by acid pH of the foregut of the insect pest.

d) Does not kill the carrier bacterium which is itself resistant to this toxin.

4. Read the following four statements (A to D) about certain mistakes in two of them.

A) The first transgenic buffalo, Rosie produced milk which was human alpha – lactalbumin enriched.

B) Restriction enzymes are used in isolation of DNA from other macromolecules.

C) Downstream processing is one of the steps of rDNA technology

D) Disarmed pathogen vectors are also used in transfer of rDNA into the host.

Which of the two statements have mistakes?

a) B and C

b) C and D

c) A and C

d) A and B

5. The colonies of recombinant bacteria appear white in contrast to blue colonies of non-recombinant bacteria because of

a) Non-recombinant bacteria containing β-galactosidase.

b) Insertional inactivation of α-galactosidase in non-recombinant bacteria.

c) Insertional inactivation of α-galactosidase in recombinant bacteria.

d) Inactivation of glycosidase enzyme in recombinant bacteria

6. Which body of the Government of India regulates GM research and safety of introducing GM organism for public services?

a) Bio-safety committee

b) Indian council of agricultural research

c) Genetic engineering approval committee

d) Research committee on Genetic manipulation

7. In genetic engineering, a DNS segment (gene) of interest is transferred to the host cell through a vector. Consider the following four agents (A to D) in this regard and select correct option about which one or more of these can be used as vector/vectors.

A) A bacterium B) Plasmid

C) Plasmodium D) Bacteriophage

a) (A), (B) and (D) only

b) (A) only

c) (A) and (C) only

d) (B) and (D) only

8. Which one of the following palindromic base sequences in DNA can be easily cut at about the middle by some particular restriction enzyme?

a) 5’ – CGTTCG – 3’ 3’ –ATGGTA -5’

b) 5’-GATATG -3’ 3’ CTACTA -5’

c) 5’ –GAATTC – 3’ 3’ – CTTAAG-5’

d) 5’ –CACGTA -3’ 3’ –CTCAGT -5’

9. Restriction endonucleases are enzymes which

a) Make cuts at specific positions within the DNA molecule.

b) Recognize a specific nucleotide sequence for binding of DNA ligase.

c) Restrict the action of the enzyme DNA polymerase.

d) Remove nucleotides from the ends of the DNA molecule.

10. Stirred – tank bioreactors have been designed for

a) Addition of preservatives of the product

b) Purification of the product

c) Ensuring anaerobic conditions in the culture vessel

d) Availability of oxygen throughout the process

11. There is a retriction endonuclease called EcoRI. What does ‘co’ part in it stand for?

a) Coelom

b) Coenzyme

c) Coli

d) Colon

12. Which one is true state regarding DNA polymerase used in PCR?

a) It is used to ligate introduced DNA in recipient cells.

b) It serves as selectable marker

c) It is isolated from a virus.

d) It remains active at high temperature.

13. For transformation, micro-particles coated with DNA to be bombarded with gene gun are made up of

a) Silver or Platinum

b) Platinum or Zinc

c) Silicon or Platinum

d) Gold or Tungsten