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What structural component of bacteria benefits from phosphorus, and why is it necessary?
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Phosphorus is a critical component of DNA, RNA, ATP, and cell membranes, making it essential for genetic information transfer, energy storage, and cell structure.
What are the key characteristics and precautions of a BSL-3 laboratory?
BSL-3 labs handle pathogens that can be transmitted through the air and cause serious disease. Precautions include the use of biosafety cabinets to contain airborne pathogens and mandatory protective equipment such as gloves and eye protection.
Describe the lag phase in bacterial growth and its significance.
The lag phase is a period where bacteria adapt to a new environment and prepare for growth by synthesizing essential macromolecules. There is little to no cell division during this phase.
What strategies might be utilized in an anaerobic culture method?
Strategies include using reducing media which contain chemicals to reduce oxygen, employing gas jars for creating anaerobic environments, or using anaerobic chambers.
Why is the log phase considered the most active part of bacterial growth?
During the log phase, bacteria multiply at their maximum rate under given conditions, leading to an exponential increase in cell numbers.
What defines the 'danger zone' in microbial growth and why is it important in food preservation?
The 'danger zone' is between 15°C and 52°C (60°F - 130°F). It is important because within this temperature range, bacteria can grow rapidly, increasing the risk of foodborne illness.
Explain the function of superoxide dismutase and catalase in bacterial cells.
Superoxide dismutase converts superoxide radicals to hydrogen peroxide, while catalase then breaks down hydrogen peroxide into water and oxygen, protecting cells from oxidative damage.
Differentiate between chemically defined media and complex media with examples.
Chemically defined media have a known exact chemical composition, while complex media contain extracts such as yeast or beef, with an undefined composition. Example: LB broth (complex media) vs. minimal salts broth (defined media).
Why are trace elements necessary for microbial growth and where are they typically utilized?
Trace elements serve as cofactors for enzyme function, enabling vital biochemical reactions. Despite being needed in small amounts, they are crucial for cellular processes.
How does a selective medium like Mannitol Salt Agar (MSA) work?
MSA inhibits non-halophilic organisms through its high salt concentration and differentiates bacteria that can ferment mannitol, such as Staphylococcus aureus, by changing color.
How are microbial growth measurements differentiated between plate counts and turbidity?
Plate counts involve counting colonies formed from CFUs on a solid medium, providing a direct measure of viable cells. Turbidity measures the cloudiness of a culture, indirectly estimating cell density through light absorption.
How does binary fission contribute to bacterial reproduction and what is generation time?
Binary fission is the process where a single bacterial cell divides into two identical daughter cells. Generation time is the period it takes for a cell to divide and double its population.
What is quorum sensing and how does it relate to biofilms?
Quorum sensing is a communication method used by bacteria to coordinate behavior and gene expression based on population density. It plays a key role in the formation and maintenance of biofilms.
Describe the unique growth requirements and environments of hyperthermophiles.
Hyperthermophiles grow optimally at extremely high temperatures, around 93°C-94°C, such as in hot springs or hydrothermal vents.
How do obligate halophiles and facultative halophiles differ in their osmotic pressure requirements?
Obligate halophiles require high osmotic pressure environments (high salt concentration), whereas facultative halophiles can tolerate high osmotic pressures but do not require them for growth.
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