Metabolismo microbiano 04. Quimioorganotrofos anaerobios

Summary

This video explains the metabolism of chemoorganotrophic microorganisms that perform anaerobic respiration. These microorganisms obtain energy through chemical reactions, using organic compounds as electron donors. During anaerobic respiration, instead of oxygen, other compounds like nitrate serve as the final electron acceptors. The process involves transferring electrons through an electron transport chain, generating proton motive force that helps produce ATP. The efficiency of energy production varies depending on the electron acceptors used, with oxygen yielding the most energy. Examples like *Escherichia coli* demonstrate how these organisms can switch between aerobic and anaerobic respiration based on environmental conditions.

Takeaways

• 😀 Microorganisms classified as chemioorganotrophs obtain energy through chemical reactions, using organic compounds as electron donors.
• 😀 In anaerobic respiration, the final electron acceptor is not oxygen, but rather another oxidized compound, such as nitrate or sulfate.
• 😀 Chemioorganotrophic microorganisms direct organic matter, like glucose, to central metabolism for oxidation, generating ATP and reducing equivalents in the form of pyridine nucleotides.
• 😀 The power generated from reduced pyridine nucleotides is used to produce energy by driving the electron transport chain and forming proton motive force (PMF).
• 😀 The redox potential difference between electron donors and acceptors determines the energy released during electron transfer. This is greater in aerobic respiration compared to anaerobic respiration.
• 😀 In aerobic respiration, oxygen acts as the final electron acceptor, resulting in a higher energy yield. In anaerobic respiration, compounds like nitrate act as electron acceptors, yielding less energy.
• 😀 Some microorganisms can perform both aerobic and anaerobic respiration depending on environmental conditions. For example, Escherichia coli uses oxygen for aerobic respiration but switches to nitrate in anaerobic conditions.
• 😀 The electron transport chain is located in the cell membrane, where pyridine nucleotides pass electrons through various transporters, generating energy to pump protons across the membrane.
• 😀 The proton gradient generated by the electron transport chain creates the proton motive force, which is used to synthesize ATP, move flagella, or transport nutrients into the cell.
• 😀 The amount of energy generated during respiration is proportional to the redox potential difference between electron donors and acceptors. The greater the difference, the more energy is released.

Q & A

What is the metabolism of chemoorganotrophic microorganisms that perform anaerobic respiration?

Chemoorganotrophic microorganisms obtain energy from chemical reactions. When they perform anaerobic respiration, they use an oxidized compound, other than oxygen, as the final electron acceptor.

How do chemoorganotrophic microorganisms process organic matter like glucose?

These microorganisms direct organic matter, such as glucose, to central metabolism, where it is oxidized to obtain a small amount of energy in the form of ATP, along with metabolic precursors and reduced pyridine nucleotides.

What role do pyridine nucleotides play in anaerobic respiration?

Pyridine nucleotides, when reduced, act as electron donors in the electron transport chain, facilitating the transfer of electrons to various acceptors, such as nitrate, in anaerobic respiration.

How does the electron transport chain function in anaerobic respiration?

In anaerobic respiration, the electron transport chain is located in the cell membrane. Electrons are transferred through various carriers, generating a proton gradient across the membrane, which powers ATP production through ATP synthase.

What is the proton motive force (PMF) and how is it generated?

The proton motive force is generated by the proton gradient created during electron transfer. It is used to synthesize ATP and can also be utilized for flagellar movement or nutrient transport.

Why is the energy produced in anaerobic respiration lower than in aerobic respiration?

The energy produced in anaerobic respiration is lower because the redox potential difference between electron donors and acceptors is smaller than in aerobic respiration, resulting in less energy being released.

What is the difference between aerobic and anaerobic respiration in terms of electron acceptors?

In aerobic respiration, oxygen is the final electron acceptor, while in anaerobic respiration, other oxidized compounds, such as nitrate, fumarate, or sulfur compounds, are used as electron acceptors.

Can microorganisms perform both aerobic and anaerobic respiration?

Yes, some microorganisms can switch between aerobic and anaerobic respiration depending on the availability of oxygen in the environment, such as Escherichia coli.

What is the energy yield difference between respiration with oxygen and respiration with nitrate?

Respiration with oxygen yields more energy because the redox potential difference is larger compared to respiration with nitrate, which produces less energy.

What happens when electrons are transferred along the electron transport chain in anaerobic respiration?

As electrons are transferred through the electron transport chain, energy is released and used to pump protons across the membrane, creating a proton gradient that is used to generate ATP and other cellular functions.