Microbial Growth and Interactions Lectures

These flashcards cover key concepts from microbial growth phases, factors affecting growth, key genetic experiments, and types of microbial interactions.

What are the phases of the microbial growth curve?

Lag Phase, Log Phase, Stationary Phase, Death Phase.

What happens during the Lag Phase of microbial growth?

Cells adjust to the new environment; no division occurs.

Why is the Log Phase significant in microbial growth?

Cells are healthiest and dividing at a constant rate.

What occurs during the Stationary Phase?

Growth equals death as nutrients are used, and waste accumulates.

What happens in the Death Phase of the microbial growth curve?

More cells die than grow due to limited nutrients and toxic waste.

What effect does high salt concentration have on bacteria?

It causes plasmolysis, where water leaves the cell.

What are halophiles?

Bacteria that tolerate high salt concentrations.

What are the three types of pH-loving microorganisms?

Acidophiles (low pH), Neutrophiles (neutral pH), Alkaliphiles (high pH).

How does temperature affect microbial growth?

It affects membrane fluidity and enzyme function.

What characterizes mesophiles?

They prefer moderate temperatures, such as human body temperature.

Who conducted the experiment that first provided evidence DNA can transfer traits?

Griffith.

What did Avery, MacLeod & McCarty prove?

DNA is the transforming principle and genetic material.

What did Hershey & Chase's experiment confirm?

DNA is the hereditary material.

What is mutualism?

A symbiotic relationship where both organisms benefit.

Give an example of commensalism.

A. fumigatus using human lungs without harm.

What is amensalism?

A relationship where one organism is harmed and the other is unaffected.

Define predation.

One organism kills and consumes another.

What is parasitism?

A relationship where one organism benefits at the expense of another.

What is the significance of biofilms?

They can increase infection risk by resisting host defenses.

What type of interaction is represented by vampirococci feeding on chromatium?

Predation.

How does the Type VI secretion system operate in bacteria?

Transformed DNA encodes for a structure that injects toxins into hosts.

What is the relationship between coral and zooxanthellae?

Mutualism.