metabolic diversity

What are the three types of microbial diversity?

Phylogenetic diversity, Metabolic diversity, and Functional diversity.

What is phylogenetic diversity?

The evolutionary relationships between organisms.

What is metabolic diversity?

The different biochemical processes microorganisms use to obtain energy.

What is functional diversity?

Differences in organism function, morphology, and ecological roles.

What are the three major types of metabolism discussed in this lecture?

Phototrophy, respiration, and fermentation.

What is phototrophy?

The use of light energy to produce ATP.

What is photosynthesis?

The conversion of light energy into chemical energy.

What is a phototroph?

An organism that uses light as its energy source.

What is an autotroph?

An organism that uses CO₂ as its carbon source.

What is a photoautotroph?

An organism that uses light for energy and CO₂ as its carbon source.

What is the main purpose of photosynthesis?

To convert light energy into ATP and reducing power for carbon fixation.

What reducing molecule is produced during photosynthesis?

NADPH.

Why is NADPH important?

It provides reducing power to convert CO₂ into organic molecules.

What are the two major types of photosynthesis?

Oxygenic and anoxygenic photosynthesis.

What electron donor is used in oxygenic photosynthesis?

Water (H₂O).

What is produced when water is oxidized in oxygenic photosynthesis?

Oxygen (O₂).

Which organisms perform oxygenic photosynthesis?

Plants, algae, and cyanobacteria.

What electron donor is commonly used in anoxygenic photosynthesis?

Hydrogen sulfide (H₂S).

Does anoxygenic photosynthesis produce oxygen?

No.

Which bacteria commonly perform anoxygenic photosynthesis?

Purple sulfur bacteria and green sulfur bacteria.

What is chlorophyll?

The main light-harvesting pigment in plants and cyanobacteria.

What is bacteriochlorophyll?

A photosynthetic pigment found in photosynthetic bacteria.

Why do different pigments exist?

They absorb different wavelengths of light, allowing organisms to occupy different environments.

What are the two main parts of the photosynthetic apparatus?

Light-harvesting complexes and reaction centers.

What happens in the reaction center?

Light excites electrons, which enter an electron transport chain.

What is photophosphorylation?

The production of ATP using light-driven electron transport.

What is cyclic electron flow?

Electrons return to the reaction center, producing ATP but not NADPH.

Which type of photosynthesis commonly uses cyclic electron flow?

Anoxygenic photosynthesis.

How many photosystems are used in oxygenic photosynthesis?

Two (Photosystem II and Photosystem I).

What does Photosystem II primarily produce?

ATP and electrons from water.

What does Photosystem I primarily produce?

NADPH.

What is the Calvin cycle?

The process that fixes CO₂ into sugars.

Does the Calvin cycle directly require light?

No, it uses ATP and NADPH generated by the light reactions.

What enzyme fixes CO₂ during the Calvin cycle?

Rubisco.

What are carboxysomes?

Bacterial microcompartments that concentrate CO₂ around Rubisco.

Why are carboxysomes beneficial?

They improve carbon fixation and reduce oxygen interference with Rubisco.

What is respiration?

The transfer of electrons from donors to acceptors through an electron transport chain to generate ATP.

What is an electron donor?

A molecule that loses electrons.

What is an electron acceptor?

A molecule that gains electrons.

What membrane structures are involved in respiration?

Electron transport chains embedded in the membrane.

What is the proton motive force (PMF)?

A proton gradient across the membrane used to drive ATP synthesis.

How is ATP produced during respiration?

ATP synthase uses the proton motive force.

What determines how much energy respiration yields?

The difference in reduction potential (ΔE°) between electron donor and acceptor.

What is the redox tower?

A chart ranking electron donors and acceptors by reduction potential.

What does a larger ΔE° indicate?

More energy released and more ATP produced.

What is chemolithotrophy?

The use of inorganic compounds as electron donors for energy.

What does "litho" mean?

Rock or inorganic.

What are common inorganic electron donors?

H₂, NH₃, H₂S, Fe²⁺, and sulfur.

What is a chemolithoautotroph?

An organism that uses inorganic compounds for energy and CO₂ as its carbon source.

What is iron oxidation?

The oxidation of Fe²⁺ (ferrous iron) to Fe³⁺ (ferric iron).

Which bacterium is a classic iron oxidizer?

Acidithiobacillus ferrooxidans.

Why does iron oxidation provide little energy?

The difference in reduction potential is small.

Why must iron oxidizers process large amounts of iron?

Because each oxidation reaction produces little ATP.

What is fermentation?

An anaerobic process that produces ATP without an electron transport chain.

Does fermentation require oxygen?

No.

Does fermentation use an external electron acceptor?

No.

How is ATP produced during fermentation?

By substrate-level phosphorylation.

What is substrate-level phosphorylation?

Direct transfer of a phosphate group to ADP to make ATP.

In fermentation, what serves as both electron donor and electron acceptor?

Organic molecules.

Name common fermentation products.

Lactic acid, ethanol, acetate, butyrate, propionate, and CO₂.

Which organism performs alcoholic fermentation?

Yeast.

Which organism performs lactic acid fermentation?

Lactobacillus.

Why is fermentation important in food production?

It produces yogurt, cheese, bread, beer, wine, and many fermented foods.

What is syntrophy?

A cooperative relationship where two microorganisms depend on each other to metabolize a substrate.

Why is syntrophy necessary?

Some reactions are energetically unfavorable unless another organism removes the products.

Which fermentation product is commonly removed during syntrophy?

Hydrogen gas (H₂).

What type of microorganism commonly partners with fermenting bacteria?

Methanogens.

What do methanogens produce?

Methane (CH₄).

How does removing hydrogen help fermentation?

It lowers product concentration, making the reaction energetically favorable.

Where is syntrophy commonly found?

Wetlands, sediments, wastewater treatment plants, and the rumen.

What is ΔG?

The actual free energy change under cellular conditions.

Why is ΔG important in syntrophy?

Removing products makes ΔG more negative, allowing reactions to proceed.

Compare phototrophy, respiration, and fermentation.

Phototrophy uses light, respiration uses an electron transport chain, and fermentation produces ATP by substrate-level phosphorylation without an electron transport chain.

Which metabolism generally produces the most ATP?

Respiration.

Which metabolism produces ATP directly from glycolysis?

Fermentation.

Which metabolism requires light?

Phototrophy.

Which metabolism commonly uses inorganic electron donors?

Chemolithotrophy.

Which metabolism produces oxygen?

Oxygenic photosynthesis only.