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प्रश्न
Explain briefly:
PCR
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उत्तर
PCR (Polymerase Chain Reaction) is a technique used to create multiple copies of a specific DNA segment in vitro. It amplifies DNA by repeated cycles of three steps:
- Denaturation: Heating the double-stranded DNA to around 94°C to separate it into single strands.
- Annealing: Cooling to 46-60°C to allow short primers to bind to complementary sequences on the single-stranded DNA.
- Extension: Raising the temperature to about 72°C so a heat-stable DNA polymerase (Taq polymerase) synthesizes new complementary strands, duplicating the target DNA.
Repeating these cycles exponentially amplifies the DNA segment, producing millions of copies rapidly. PCR is widely used for DNA amplification, genetic fingerprinting, disease detection, DNA sequencing, and molecular mapping. It was introduced by Kary Mullis in 1985 and relies on the thermostable enzyme from Thermus aquaticus to function at high temperatures without being denatured.
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संबंधित प्रश्न
Suggest and describe a technique to obtain multiple copies of a gene of interest in vitro.
Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).
From what you have learnt, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?
Can you recall meiosis and indicate at what stage recombinant DNA is made?
Describe briefly the following:
Bioreactors
Describe briefly the following:
Downstream processing
Answer the following question:
Describe the formation of recombinant DNA by the action of EcoRI.
Which of the following term used for defining a viral genome incorporated into host DNA?
______ plays an important role in blood clotting.
Gene Amplification using primers can be done by ______.
Blood stains are found at the site of a murder. It DNA profiling technique is to be used for identifying the criminals, which of the following is ideal for use?
The first step in recombinant DNA technology is
In addition to the Taq polymerase enzyme, which other thermostable DNA polymerases have been isolated to be used in PCR?
In PCR, primers are used for ______.
During the process of gene amplification using PCR, if a very high temperature is not maintained in the beginning, then which of the following steps of PCR will be affected first?
Rising of dough is due to ______.
Which of the following steps are catalysed by Taq DNA polymerase in a PCR reaction?
A bacterial cell was transformed with a recombinant DNA molecule that was generated using a human gene. However, the transformed cells did not produce the desired protein. Reasons could be ______.
Which of the following should be chosen for best yield if one were to produce a recombinant protein in large amounts?
How is copy number of the plasmid vector related to yield of recombinant protein?
While doing a PCR, ‘denaturation’ step is missed. What will be its effect on the process?
Do biomolecules (DNA, protein) exhibit biological activity in anhydrous conditions?
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.
Read the paragraph given below and answer and questions that follow:
| Enzyme Taq polymerase, is extracted from a eubacterial microorganism Thermus aquaticus from Yellowstone National Park in Montana, USA and isolated by Chien et al. (1976). Taq polymerase successfully replaced the DNA polymerase from E.coli that was being used in PCR earlier and this shift revolutionised the PCR technique. |
- Taq polymerase after its discovery replaced E.coli DNA polymerase in PCR technique. Explain giving reasons why was the need felt for the change?
- What is a primer and its importance in PCR?
- Write the importance of PCR as a diagnostic tool.
Write the scientific name of the source organism of the thermostable DNA polymerase used in PCR.
State the advantage of using Thermostable DNA polymerase.
