Critical Thinking Questions (Chapter 4)
Quorum sensing is a process used by many bacteria for communication. It involves the production of molecules called autoinducers, which act as bacterial chemoattractants. Describe how a motile bacterium would use its flagellum to respond to such a stimulus in its environment.
A bacterium that sensed this chemoattractant would use its flagella to go towards it. First, it would use its flagella to produce a tumbling motion to change direction towards the chemoattractant. Then it would use its flagella to run to move straight towards the the chemoattractant.
Describe the characteristics of an endospore-producing bacterium that make it an ideal candidate for bioterrorism but an undesirable intruder in a hospital setting.
During harsh conditions bacteria can survive by developing a tough covering to protect themselves. This hard outer covering is called an endospore. Endospores formed by bacteria when nutrients are scarce. Endospores are extremely resistant to drying out, heat, radiation, and lethal chemicals. They can resist being boiled in water for several hours. Alcohol, bleach and even up for 400 rad of radiation do not affect the endospore. Their persistence in the environment make them an ideal candidate for bioterrorism. Undesirable in the hospital because these endospores can spread rapidly. They are difficult to eradicate using regular cleaning regimen . Agents capable of killing spores must be used.
Study this figure. How would it be drawn differently if the archaea were more closely related to bacteria than to eukaryotes?
The ancestral branch of archaea would be coming off of the ancestral branch of bacteria.
Do you believe that the bacteria spelling "Klebsiella" or the bacteria spelling "S. aureus" possess the larger capsule? Defend your answer.
The bacteria Klebsiella has a larger capsule because the letters look larger and more risen than the other. The larger capsuled bacteria would appear the largest on the plate.
Provide evidence in support of or refuting the following statement: The cell, or cytoplasmic, membrane is a nonessential structure in bacteria because its function is replaced by the cell wall in these microbes.
The cell membrane plays an important role of protecting bacteria from osmotic imbalances and stops the leakage of metabolites and other cellular structures into outer environment. Bacteria cannot survive without a cell wall.
Based upon your knowledge of cell wall structure, explain how the microbes causing meningitis and typhoid fever can induce fever and systemic shock in an infected patient.
The outer most layer of outer membrane contains lipopolysaccharide. The lipid portion of LPS is referred to as endotoxin because it stimulates fever and shock reactions to gram-negative infections such as meningitis and typhoid fever.
Explain why the production of endospores is not considered a method of reproduction in most bacterial species.
These endospores are produced inside of a cell. There is no increase in cell number in their formation.
Define the term ubiquitous and explain whether this term can be used appropriately to describe bacteria and archaea.
Ubiquitous is described to be present everywhere at the same time. It can be used to properly describe bacteria and archaea because they found everywhere. This term is used to define bacteria and archaea both in the world today . It is used to describe these microorganisms due to their ability to adapt, their long history of survival and locations. Bacteria are found in all regions of the world. The bacteria produce endospores, which are able to survive without nutrients and in the most unlikely habitats . Archaea are known for their survival in the most extreme surroundings, which includes those with extreme pH, heat, and pressure. Bacteria and Archaea's ability to survive in both harsh and nutrient-rich conditions that makes the term ubiquitous a fitting description for these organisms.
