Question

1. Describe the formation and function of bacterial endospores 2. Describe four reasons why eukaryotic reproduction is more complex than prokaryotic reproduction. 3. Contrast meiosis with mitosis, mentioning homologous chromosomes, chromatids, 4. Define virus and virion, and describe the parts of a virion. 5. Identify and describe the portals through which pathogens invade the human body. tetrads and crossing over.

Answer 1

An endospore is a dominant, tough, non-reproductive structure formed by bacteria. It is produced by bacteria under starvation conditions ( lack of nitrogen and carbon sources) and under extreme environmental conditions. Endospores are formed by the process of sporulation. The main steps of endospore formation are -

• In unfavorable conditions, the bacteria detect this unfavorable conditions and start the endosporulation process. In this process, first, the DNA is replication and a spore septum (membrane wall) starts forming between it and rest of cell.
• Next, the cell plasma membrane surrounds this wall, it pinches off and enclosed the DNA with double membrane structure forming forespore. Calcium dipicolinate is incorporated into the forespore during this time, this dipicolinic acid stabilizes the DNA and protein in the endospore.
• After this, a cortex made of peptidoglycan is formed between the 2 layers.
• In the last stage, the endospore is dehydrated and matured. This is allowed to mature and then released from the mother cell.

The function of endospore- The main function of endospores is to ensure bacterial survival through the environmental stress condition and extreme conditions. Endospores provide resistance from UV and gamma radiation, extreme temperature, starvation and chemical disinfectants.