Microbiology

What is metabolism in cells?

It is the controlling of chemical reactions, essential for reproduction and growth.

What are the common nutrients required for microbial growth?

Carbon, Nitrogen, Oxygen, and Hydrogen.

What are autotrophs?

Organisms that utilize inorganic carbon sources to make organic compounds.

What are heterotrophs?

Organisms that obtain organic molecules from other organisms.

What are chemotrophs?

Organisms that acquire energy from redox reactions involving organic chemicals.

What role does oxygen play for obligate aerobes?

Oxygen serves as the final electron acceptor in their electron transport chains.

What is nitrogen fixation?

The process by which certain organisms convert nitrogen gas into ammonia, making nitrogen available for life.

What are the two types of relationships described in microbial interactions?

Antagonistic relationships (harmful) and beneficial relationships (synergistic and symbiotic).

Describe the lag phase in the microbial growth curve.

The lag phase is when cells adjust to their new environment and do not reproduce immediately.

What are psychrophiles?

Microorganisms that grow best at temperatures below 15°C.

What are mesophiles?

Microorganisms that thrive in moderate temperatures, typically between 20°C to 40°C.

What is the purpose of a chemostat?

To maintain a continuous culture of microorganisms at a specific growth phase by supplying fresh medium.

How do direct methods of counting cells differ from indirect methods?

Direct methods involve counting cells without incubation, while indirect methods estimate cell numbers based on measurable changes in the culture.

What is hydrogen peroxide in terms of its effect on aerobic cells?

Hydrogen peroxide is toxic and can damage aerobic cells unless neutralized by catalase or peroxidase.

What are aerobic organisms?

Organisms that require oxygen for growth.

What is a biofilm?

A community of microorganisms that live together in a sticky matrix, providing protection and enhanced growth.

What are facultative anaerobes?

Microorganisms that can grow with or without oxygen.

What is the optimum growth temperature for enzymes and metabolic activities?

The temperature at which metabolic activities produce the highest growth rate for microorganisms.

What type of media is used for culturing anaerobes?

Anaerobic media, which protects cells from exposure to free oxygen.

What is the significance of trace elements for microbial nutrition?

Trace elements are required in small amounts for various metabolic processes.