Question

1. Identify the basic shapes of bacteria and formation under the microscope. 2. Describe how bacteria are identified and named under the microscope. 3. Distinguish between Gram positive and Gram negative bacteria. 4. Explain the ways bacteria reproduce themselves. 5. Describe what makes prokaryotic cells different from eukaryotic cells. 6. Identify the internal and external structure of bacteria. 7. Define plasmids and how bacteria use them 8. Describe the 2 categories of bacteria found in the Moneran kingdom. 9. Bacterial cells can have various external features. Describe the functions of each of the following: a. Flagella b. Fimbriae C. Capsule 10. What is the "nucleoid" region of the bacterial cell and why is it called that name?

Answer 1

1.) Bacteria are microscopic and lack a nucleus. There are 4 basic structures of bacteria- Rod shaped, Coccus, Vibrio and Spiral shaped. Rest of the structural shapes like- diplococci, staphylococci etc. are the form of coccus when they divide and remains attached.

2.) Under the microscope the shape of the bacterial shapes play important role in the identification of the bacteria. Common example of rod shaped bacteria is Bacillus subtilis. Same as in the spiral shaped bacteria common example is Spirillum or Sulphar spirilla.

3.) Bacteria cells have an outer cell wall which is chemically composed of peptidoglycan also called as Murein. The thickness of this peptidoglycan layer distinguishes between the Gram positive and Gram negative bacteria. Gram positive bacteria have a single layer of thickness about 20-80 nm while Gram negative bacteria are covered by cell wall 2-7 nm thick which is covered by 7-8 nm thick outer layer of peptidoglycan.

4.) Bacteria reproduce themselves by asexually and sexually. Asexually they reproduce by Binary fission. In Binary fission chromosome copies itself and form two identical copies of cell. Sexually bacteria reproduce by the process of Conjugation, Transformation and Transduction. In Conjugation the sex pilus help in exchanging the DNA. In Transformation bacteria takes up the piece of DNA from their environment. And in Transduction, the exchange of DNA is done by involvement of virus. Viruses which infect the bacteria, carry bacterial genetic material and upon infection they transfer genetic material to other bacteria.