Microbiology Chapter 6 EXAM2

Microbiology vocabulary flashcards based on lecture notes.

What are essential nutrients?

Compounds an organism cannot make itself and must acquire from its environment.

What are macronutrients

Nutrients important for cell structure and metabolism.

Why does a species grow within a specific temperature range?

Its enzymes have evolved to tolerate that range

Micronutrients

Trace elements important for enzyme function and protein structure.

Osmotic Lysis

Cell bursts due to large influx of water.

Plasmolysis

Cell shrinks due to water loss.

Halophiles

Bacteria that can tolerate high salt concentrations (up to 35% NaCl).

Optimal Temperature

The temperature at which growth and metabolism are fastest.

Psychrophiles

Microbes that thrive in very cold temperatures (-5 to 15°C).

Define psychrotolerant

Microbes that can grow from 0 to 30°C.

Mesophiles

Microbes that grow best at 20 to 45°C (human body temp = 37°C).

Thermophiles

Microbes that prefer 45 to 80°C.

Extreme Thermophiles

Microbes that grow in 65 to 110°C.

Acidophiles

Microbes that thrive in acidic environments (pH 1 to 5).

Neutrophiles

Microbes that thrive in pH 5 to 8 (most pathogens).

Alkalinophiles

Microbes that thrive in alkaline conditions (pH 9 to 11).

Obligate Aerobe

Requires oxygen and grows only at the top of a tube.

Microaerophile

Requires low oxygen levels and grows slightly below the top.

Obligate Anaerobe

Cannot tolerate oxygen and grows only at the bottom.

Aerotolerant Anaerobe

Does not use oxygen but can tolerate its presence; grows evenly.

Facultative Anaerobe

Can grow with or without oxygen but grows better with oxygen.

Capnophiles

Microbes that grow best at higher CO2 levels.

Mutualism

A symbiotic relationship where both organisms benefit.

Commensalism

One organism benefits; the other is neither helped nor harmed.

Parasitism

One organism benefits at the expense of the host.

Synergism

Microbes cooperate and share nutrients.

Antagonism

Microbes compete and inhibit or destroy each other.

Binary Fission

Asexual reproduction by splitting into two cells.

When does sporulation occur

During the stationary or death phase when conditions worsen

When is penicillin most effective

During the log phase when cells are actively dividing

What are the four phases of the bacterial growth curve?

Lag (no division), Log (exponential growth), Stationary (growth slows), Death (cells die rapidly).

What does radiation do to microbes?

Causes DNA damage and can control microbial growth

What does catalase do?

Converts H2O2 into water and O2.

What does superoxide dismutase (SOD) do?

Neutralizes ROS into H2O2 and O2.

Why is oxygen toxic to some microbes?

It produces reactive oxygen species (ROS) that damage cells

How does pH help control microbial growth?

Extremes in pH can inhibit or kill microbes.

How does osmotic pressure help control microbial growth?

High salt or sugar can cause plasmolysis

How does temperature help control microbial growth?

Extreme heat or cold can slow or kill microbes.

What structure protects against osmotic lysis

The cell wall.