Question

9. (7) What are some similarities and differences between the signal transduction systems of the regulation of chemotaxis and quorum sensing? Your explanation should include a discussion of the functions of the components of each system (e.g. What is the sensor? What is the kinase? What is the response protein and what does it do?).

10. (7) Compare fermentation and respiration: in which process would you have to consume more glucose to get equivalent amounts of ATP? What waste products are produced? How do these waste products affect the overall growth of the bacterium?

11. (6) One result of catabolite repression is diauxic growth of a culture. Briefly explain this phenomenon in relation to global control systems and explain how catabolite repression benefits cells that use it.

Answer 1

10. Respiration:-

• complete oxidation of glucose
• aerobic condition.
• undergoes Kreb cycle.
• in mitochondria.
• enzyme involved pyruvate dehydrogenase
• yielding 38 ATP
• complete degradation to CO2 and H2O
• oxidation of NADH to NAD+ is very vigorous.

Fermentation:

• partial breakdown of glucose
• net gain only 2 ATP
• Oxidation of NADH to NAD+ is very slow
• ethanol is produced
• anaerobic condition.
• enzymes evolved - pyruvic acid decarboxylase and alcohol dehydrogenase.
• No kreb cycle

In fermentation we have to consume more glucose to get equivalent amounts of ATP as respiration.

Waste products are CO2 and Water and in fermentation lactic acid also.

7% of CO2 present in plasma in their molecular form, 70-80% converted to hydrocarbonate ions and the remainder binds with Hb and got exhaled out. H2O produced diffuses out of cell to bloodstream and removes as perspiration or along with solutes they excreted out as urine. Lactic acid produced accumulates in muscle and produces pain.

( as per the rules only 1 question can be answered.. repost the other questions to get answers.)