Around , established four proofs that could be used to determine an organism’s pathogenicity and related disease. he also developed many of the laboratory techniques that are still used today.

1875, Koch

Explanation:

What is now known today as Koch´s postulates were formulated by Robert Koch( German physician and bacteriologist) and Friedrich Loeffler in 1884. It allows one to determine whether a relationship exists between a particular organism and a disease. It forms a causative relationship between a microbe and its respective disease. Koch used his postulates to desribe the etiology of two diseases in particular; cholera and tuberculosis. These postulates were generated before the complete understanding of the modern concepts of microbial pathogenesis and as a result cannot be aplied to asyntomatic carriers and viruses.

Koch´s postulates states the following:

There exists a molecular version of Koch´s postulate which states the following;

1. The gene/factor should be present in all pathogenic strains of the organism and absent from non pathogenic strains.

2.i) the molecular disruption should reduce the virulence of the bacterial strain

ii) introducing the cloned gene into an avirulent strain should render that strain virulent

3. The gene must be expressed at some point during the infectious process in experimentally infected animals.

4. Antibody raised against the virulence factor should offer some protection, against infection, in an experimentally infected animal.

Koch´s postulates did share some clarity to the relationship between bacterias and their respective microbes but to date cannot be used to many new discoveries and theories which we now know. As stated earlier Koch´s postultes cannot be used for viruses and asyntomatic carriers (for example play an important role in the spreading of typhoid, influenza and HIV)

d statement

explanation:

telophase and anaphase