Question

L03: Describe some main differences in cell structure that are used to distinguish bacteria, archaca, fungi, protozoa, algae, and viruses (BL4) L04: Judge the contributions of Edward Jenner, Louis Pasteur, Ignaz Semmelweis, and Robert Koch toward disproving "spontaneous generation" (BL5)

Answer 1

AnsLO3)

Cell walls are found in the cells of eubacteria, archaebacteria, fungi, algae, and plants. The cell walls vary greatly in their compositions:

1. Eubacteria. Almost all eubacterial species have cell walls containing a polysaccharide called peptidoglycan. Among the eubacteria, differences in cell wall structure are a major feature used in classifying these organisms. Two main groups can be distinguished:
   1. Gram positive bacteria
   2. Gram negative bacteria
2. Archaebacteria. The cell walls of archaebacteria are distinctive from those of eubacteria. Archaebacterial cell walls are composed of different polysaccharides and proteins, with no peptidoglycan. Many archaebacteria have cell walls made of the polysaccharide pseudomurein.
3. Fungi. Fungal cell walls are typically composed of the polysaccharides chitin and cellulose.
4. Algae and Plants. The cell walls of algae and plants are composed mainly of the polysaccharide cellulose.

AnsLO4)  Louis Pasteur, in 1864, settled the argument once and for all. Taking the basic idea of the two scientists from the 1700s and answering critics that said air was necessary for life, Pasteur developed a special flask. It had a curved neck that allowed air in, but would trap any microorganisms and not let them contaminate his findings.

Pasteur showed that his flask was free from microorganisms, even though it was open to the air. For a year, there was no microbial growth. Until Pasteur broke the neck of the flask. And when microorganisms appeared, he proved to the world that life could only come from other life.

Edward Jenner-

Through a series of unexpected events Jenner were led to the discovery of immunization and to the eventual elimination of the scourge of smallpox from the earth.

The credit for the invention of inoculation now goes to Edward Jenner

Ignas Semmelweis-He reasoned that there was an INVISIBLE AGENT that caused both deaths and that one could transfer it from the autopsy room to the birthing rooms and thus infect the mothers during birthing.

Robert Koch-He became famous for isolating Bacillus anthracis , the Tuberculosis bacillus and Vibrio cholerae and for his development of Koch’s postulates.

All of these sceintists hence proved theory of spontaneous generation incorrect.