Biology

Biotechnology : Principles and Processes

Question:

What would happen when one grows a recombinant bacterium in a bioreactor but forget to add antibiotic to the medium in which the recombinant is growing?

Answer:

In the absence of antibiotic, there will be no pressure on recombinants to retain the plasmid (containing the gene of your interest). Since, maintaining a high copy number of plasmids is a metabolic burden to the microbial cells, will thus tend to lose the plasmid.

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Biotechnology : Principles and Processes

Q 1.

Restriction enzymes that are used in the construction of recombinant DNA are endonucleases which cut* the DNA at specific-recognition sequence'. What would be the disadvantage if they do not cut the DNA at specific- recognition sequence? .

Q 2.

A plasmid DNA and a linear DNA (both are of the same size) have one site for a restriction endonuclease. When cut and separated on agarose gel electrophoresis, plasmid shows one DNA band while linear DNA shows two fragments. Explain.

Q 3.

Would you choose an exonuclease while producing a recombinant DNA molecule?

Q 4.

Do biomolecules (DNA, protein) exhibit biological activity in anhydrous conditions?

Q 5.

How is copy number of the plasmid vector related to yield of recombinant protein?

Q 6.

Make a chart (with diagrammatic representation) showing a restriction enzyme, the substrate DNA on which it acts, the site at which it cuts DNA and the product it produces.

Q 7.

What does competent' refer to in competent cells used in transformation experiments?

Q 8.

Describe the role of CaCl2 in the preparation of competent cells.

Q 9.

Identify and explain steps A',  B' and C' in the PCR diagram given below.
ncert-exemplar-problems-class-12-biology-biotechnology-principles-and-processes-2

Q 10.

Explain briefly
(a)PCR
(b)Restriction enzymes and DNA
(c)Chitinase

Q 11.

A plasmid without a selectable marker was chosen as vector for cloning a gene. How does this affect the experiment?

Q 12.

Can you think and answer how a reporter enzyme can be used to monitor transformation of host cells by foreign DNA in addition to a selectable marker?

Q 13.

Can you recall meiosis and indicate at what stage a recombinant DNA is made?

Q 14.

From what you have learnt, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?

Q 15.

What is the significance of adding proteases at the time of isolation of genetic material (DNA)?

Q 16.

What would be the molar concentration of human DNA in a human cell? Consult your teacher.

Q 17.

What does H' in d' and III' refer to in the enzyme Hind III?

Q 18.

Describe the role of Agrobacterium tumafaciens in transforming a plant cell.

Q 19.

While doing a PCR, denaturation' step is missed. What will be its effect on the process?

Q 20.

How does one visualise DNA on an agarose gel?

Q 21.

What would happen when one grows a recombinant bacterium in a bioreactor but forget to add antibiotic to the medium in which the recombinant is growing?

Q 22.

What is meant by gene cloning?

Q 23.

Do eukaryotic cells have restriction endonucleases? Justify your answer.

Q 24.

Besides better aeration and mixing properties, what other advantages do stirred tank bioreactors have over shake flasks?

Q 25.

What modification is done on the Ti plasmid of Agrobacterium tumifaciens to convert it into a cloning vector?

Q 26.

For selection of recombinants, insertional inactivation of antibiotic marker has been superseded by insertional inactivation of a marker gene coding for a chromogenic substrate. Give reasons.

Q 27.

A recombinant DNA molecule was created by ligating a gene to a plasmid vector. By mistake, an exonuclease was added to the tube containing the recombinant DNA. How does this affect the next step in the experiment, i.e. bacterial transformation?

Q 28.

Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).

Q 29.

Restriction enzymes should not have more than one site of action in the cloning site of a vector. Comment.

Q 30.

Both a wine maker and a molecular biologist who had developed a recombinant vaccine claim to be biotechnologists. Who in your opinion is correct?

Q 31.

A mixture of fragmented DNA was electrophoresed in an agarose gel. After staining the gel with ethidium bromide, no DNA bands were observed. What could be the reason?

Q 32.

Collect 5 examples of palindromic DNA sequences by consulting your teacher. Better try to create a palindromic sequence by following base-pair rules.

Q 33.

Describe briefly the followings:
(a)Origin of replication
(b)Bioreactors
(c)Downstream processing

Q 34.

Name the regions marked A, B and C.
ncert-exemplar-problems-class-12-biology-biotechnology-principles-and-processes-3

Q 35.

Name a recombinant vaccine that is currently being used in vaccination program.

Q 36.

Illustrate the design of a bioreactor. Highlight the difference between a flask in your laboratory and a bioreactor which allows cells to grow in a continuous culture system.