The bright-field microscopy produces an image with a coloured specimen having lightened background. Generally, the microorganisms do not absorb light, but the organisms can absorb the light after staining. The optical lens, i.e. condenser lens and the path of light coming from the light source illuminator produce a bright-field image with higher contrast and magnification. …
The continuous culture is an open cultivation process, in which the cell growth is maintained in the continuous mode of operations. It works as an open cultivation system, in which the fresh nutrient medium is continuously added into the culture vessel rather than recycling and reuse of the nutrients or substrate. There is an inlet pump …
The active site of an enzyme is the region, which shows the highest metabolic activity by catalysing the enzyme-substrate complex into the products. The active site is found deep inside the enzyme, which resembles a hole or small depression. An active site is a region combining the specific substrate molecule with the enzyme and thus …
Watson and Crick model of DNA provides one of the best ways to demonstrate the structure of double-helix DNA. A DNA is a polymer composed by the combination of several monomer units (deoxyribonucleotides) linked by the phosphodiester bond. In the discovery of DNA, many scientists have contextualized the structure of DNA, its components and composition …
Meselson and Stahl experiment gave the experimental evidence of DNA replication to be semi-conservative type. It was introduced by the Matthew Meselson and Franklin Stahl in the year 1958. Matthew Meselson and Franklin Stahl have used E.coli as the “Model organism” to explain the semiconservative mode of replication. There are three modes of replication introduced …
Hershey and Chase experiment give practical evidence in the year 1952 of DNA as genetic material using radioactive bacteriophage. Griffith also explained the transformation in bacteria and concluded that the protein factor imparts virulence to the rough strain, but it was not proved to be genetic material. Avery, Macleod and McCarthy further studied the Griffith …
A restriction enzyme is produced within the bacterial cell due to which it is also called “Restriction endonuclease”. In 1978, Werner Arber, Daniel Nathans, Hamilton O Smith won the Nobel Prize for the characterization and discovery of restriction enzyme during the study of Entero-bacteriophage. According to their study, the bacteria possess some restriction activity that …
Transfer RNA is an RNA type that acts as the intermediary element, and plays a significant role in the loading and transferring amino acids to the site of protein synthesis, i.e. Ribosome. The t-RNA first decodes the information or the nucleotide sequences carried by the m-RNA. Therefore, t-RNA also plays a major role in translating …
The difference between flagella and pili is due to the difference in the properties like structure, origination and functional role. Both are the two common types of surface appendages, which aid in locomotion and attachment of the organisms. Structure: The structure of flagellum appears whip-like, whereas pili appear thread or hair-like. Origination: The emergence of …
The difference between amphibians and reptiles is mainly due to the differences in the properties like the existence of dual life cycle, type of fertilization and skin type. Both amphibians and reptiles are the animals belonging to the phylum “Chordata” and considered as “Cold-blooded animals”. Life cycle: Amphibians have dual existence in their life cycle, …