Viral genomes consist of either DNA or RNA, but never both: True/False

The primary function of the cell envelope is to protect the bacterial cell and maintain its structural integrity, not to store genetic material or ribosomes. The cell envelope includes the cell wall, plasma (cytoplasmic) membrane, and, in gram-negative bacteria, an outer membrane. It provides a barrier against environmental stress, helps maintain cell shape, and regulates the movement of substances in and out of the cell. Genetic material (DNA) and ribosomes are located inside the cytoplasm, not in the cell envelope. Therefore, while the envelope is essential for survival and interaction with the environment, it does not serve as a storage site for genetic components or protein synthesis machinery.

A. Pasteur: Louis Pasteur demonstrated that microorganisms are responsible for fermentation and spoilage, supporting the germ theory of disease. He developed vaccines for diseases like rabies and anthrax, but he did not formally establish the experimental criteria proving that a specific microbe causes a specific disease.

B. Lister: Joseph Lister introduced antiseptic surgical techniques using carbolic acid to reduce postoperative infections. His work applied germ theory to clinical practice but did not provide the experimental proof linking individual microbes to specific diseases.

C. Koch: Robert Koch formulated Koch’s postulates, a set of criteria that provide experimental proof that a particular microorganism causes a specific disease. By isolating the microbe, reproducing the disease in a susceptible host, and re-isolating the same organism, he established causation.

D. Wasserman: August von Wasserman developed the Wasserman test for syphilis, a diagnostic tool for detecting infection. While important in serology, his work did not establish causation between microbes and disease.

E. Semmelweis: Ignaz Semmelweis advocated hand hygiene to reduce puerperal fever in obstetric clinics. His observations linked contaminated hands to disease transmission, but he did not experimentally prove that a specific microorganism caused a specific disease.