Question

The process by which the amount of DNA, RNA and protein in a cell present at a time can be determined is
A. Cell fractionation
B. Autoradiography
C. Phase- contrast microscopy
D Tissue culture

Answer 1

In some methods, the isolation of cellular components such as DNA,RNA protein or lipids which are followed by labelling suitable radioisotopes.

Complete answer:
- In the technique of autoradiography, radioactive isotopes (tritium, carbon-14, Phosphorus-32, Sulphur-35) are incorporated in intermediate or raw materials such as carbon dioxide, uridine, thymidine, amino acids etc.
- The study of metabolic pathways including DNA to RNA to proteins pathway, otherwise known as Central Dogma of Molecular Biology. The tissues are divided at intervals and then coated with photographic emulsion silver bromide in order to locate the product.
- Through this technique, carbon 14 has been used for working out the path of carbon assimilation by Calvin in 1955 and photorespiration. Ruben and Kamen confirmed that in photosynthesis oxygen is released by photolysis of water and not by carbon dioxide.
- Tritium in thymidine was employed by Taylor for studying chromosome replication. Tritium in uridine was used in studying RNA synthesis while tritium in amino acid like leucine is employed for study of protein synthesis.
- In laboratories gel electrophoresis is a common technique which is used to separate DNA, RNA and proteins according to their size.

Hence the correct answer is option B.

Note: In laboratories to visualize the fragments of DNA agarose gel are typically used. The concentration of agarose is used and used to make the gel depend on the size of the DNA fragments that are working with it.