cells 30

What is microbial ecology?

The study of the interrelationships between microorganisms and their environment.

What is a microbiome?

All microorganisms and their genes within a particular environment.

What is a microbial population?

A group of cells of the same microbial species.

What is a microbial community?

Interacting populations of microorganisms.

What is a pure culture?

A culture containing only one microbial species.

What is a major limitation of pure cultures?

They ignore interactions between microbes in communities.

Why are many microbes difficult to culture?

Many require interactions with other microbes or special conditions.

What is the “unseen majority” in microbiology?

The vast uncultured microbial world.

What gene is commonly used as a molecular barcode for bacterial identification?

16S rRNA gene.

What is enrichment culture?

A method that provides conditions favouring the growth of specific microbes.

What is a mesocosm?

An experimental system that simulates real-life environmental conditions.

What are the 2 linked components of metabolism?

Catabolism and anabolism.

What is catabolism?

Breakdown reactions that release energy.

What does catabolism produce?

ATP, proton motive force, and building blocks.

What is anabolism?

Biosynthetic reactions that consume energy.

What does anabolism use?

ATP and building blocks.

What are the two major things harvested during metabolism?

Energy and building blocks.

What are redox reactions?

Oxidation-reduction reactions involved in energy transfer.

What is oxidation?

Loss of electrons.

What is reduction?

Gain of electrons.

Why are redox reactions important?

They are the basis of energy transfer in cells.

What are NADH and NADPH?

Electron carriers that shuttle energy within the cell.

Are NAD+/NADH consumed during metabolism?

No, they are recycled.

What are trophic groups?

Groups of organisms classified by carbon and energy source.

What are the 4 key trophic groups of microorganisms?

Chemoautotrophs, chemoheterotrophs, photoautotrophs, and photoheterotrophs.

What energy source do phototrophs use?

Light.

What energy source do chemotrophs use?

Chemical compounds.

What carbon source do autotrophs use?

CO2.

What carbon source do heterotrophs use?

Organic compounds.

What are photoautotrophs?

Organisms that use light for energy and CO2 as a carbon source.

Give examples of photoautotrophs.

Plants, algae, and cyanobacteria.

What electron donor do cyanobacteria use during photosynthesis?

H2O.

What by-product is produced during oxygenic photosynthesis?

O2.

What is oxygenic photosynthesis?

Photosynthesis that uses water as the electron donor and produces oxygen.

What is anoxygenic photosynthesis?

Photosynthesis that uses substances like H2S instead of water and does not produce oxygen.

Which bacteria perform anoxygenic photosynthesis?

Green sulfur bacteria and purple sulfur bacteria.

What are chemoautotrophs?

Organisms that use chemicals for energy and CO2 for carbon.

Give examples of chemoautotrophs.

Sulfur bacteria and nitrifying bacteria.

What are chemoheterotrophs?

Organisms that use chemicals for energy and organic compounds for carbon.

Give examples of chemoheterotrophs.

Animals, fungi, and many bacteria.

What are photoheterotrophs?

Organisms that use light for energy and organic compounds for carbon.

What is the difference between autotrophs and heterotrophs?

Autotrophs fix CO2 while heterotrophs require organic carbon.

Why are autotrophs called primary producers?

They can produce organic molecules from CO2 independently.

Why are heterotrophs called decomposers?

They depend on fixed organic carbon produced by other organisms.

What is an organic electron donor example?

Glucose.

What is an inorganic electron donor example?

H2S.

How do microbes reduce competition in microbial mats?

By absorbing different wavelengths of light.

Why can different photosynthetic microbes coexist in the same environment?

They have complementary absorption spectra.

What are redox gradients?

Differences in oxidation-reduction conditions across environments.

How do redox gradients affect microbial communities?

Different redox conditions select for different microbes.

What does oxic mean?

Oxygen is present.

What does anoxic mean?

Oxygen is absent.

What are cable bacteria?

Bacteria that transport electrons between anoxic and oxic zones.

How do cable bacteria survive in anoxic environments?

They shuttle electrons to oxygen-rich zones.

What do cable bacteria use to transport electrons?

Conductive bacterial filaments.

Why are cable bacteria important examples in microbial ecology?

They show how microbes exploit different redox environments.

What are the two major focuses in microbial metabolism?

Carbon acquisition and energy acquisition.

What is the relationship between catabolism and anabolism?

Catabolism generates energy/building blocks while anabolism uses them for biosynthesis.

What is the basis of energy flow in ecosystems?

Redox reactions and energy harvesting.

What is the main ecological rule emphasized in the lecture?

If life exists, energy is being harvested from something.