Practical: Study of Nostoc

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 Practical: Study of Nostoc Nostoc is a filamentous, photosynthetic cyanobacterium. It commonly occurs in freshwater, moist soil, wet rocks and other damp habitats. Colonies are usually gelatinous because numerous filaments remain embedded in a mucilaginous matrix. Materials Required Fresh or preserved Nostoc material, clean glass slide, cover slip, dropper, dissecting needle, water, blotting paper and compound microscope. Procedure Take a small quantity of Nostoc colony with the help of a dissecting needle and place it on a clean glass slide. Add one or two drops of water and gently tease the material so that the filaments become separated. Place a cover slip carefully over the material without trapping air bubbles. Remove excess water with blotting paper. First observe the preparation under low power and then under high power of the compound microscope. Observations The plant body of Nostoc is thalloid and usually forms a soft, jelly-like colony. A colony contains numerous ...

Genomic DNA and c-DNA Distinguish

  Properties

             c-DNA

         Genomic DNA

(i) Principle

A fragment is a clone DNA of an active m-RNA generated by enzyme reverse transcriptase.

The fragment of desired gene is directly obtain from the restriction digestion of genomic DNA.

(ii) Use of primer

 

When eukaryotic m-RNA is used as template the poly T oligonucleotide is conveniently used as primer.

Either no primer is used or site specific primer is used.

 

(iii) Utility in case of prokaryotic DNA

The c-DNA is absolutely essential when the expression of an eukaryotic gene is required in a prokaryot.

The prokaryotic genomes do not contain any inhtron. So, their genomic library is directly expressed in the expression vector in appropriate prokaqryotic host.

(iv) Purity of product

The m-RNA is never pure and the mixture of m-RNA is used in c-DNA preparation.

DNA is always pure.

(v) Probe used for identification

The desired gene clone is identified by the probe made up of RNA or c-DNA of m-RNA.

The desired gene clone is identified by the probe made up of DNA.

(vi) Alkaline hydrolysis

(vii) RNase

It is necessary in this technique.

Used

It is not necessary in this technique.

Not used

(ix) Restriction endonuclease

Not used

Used.

 

(x) Problem 

c-DNA library has a problem that m-RNA is always incompletely copied.

Genomic library is under or over represent or even missing of DNA fragments.





Further readings:

DNA Fingerprinting

https://www.biologicalworld.in/2021/04/dna-finger-printing-or-dna-profiling.html


PCR

https://www.biologicalworld.in/2021/10/polymerase-chain-reaction-method.html


c-DNA library

https://www.biologicalworld.in/2021/10/c-dna-library.html

https://www.biologicalworld.in/2021/10/c-dna-library-protocol-and-utility.html


Genomic DNA library


https://www.biologicalworld.in/2021/10/genomic-dna-library.html

Gene delivery to a potential transgenic plant

https://www.biologicalworld.in/2022/04/gene-delivery-to-potential-transgenic.html


LIFE SCIENCE FOR SCHOOL SERVICE COMISSION

https://www.biologicalworld.in/search/label/MCQ


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