Microbial Central Metabolism

What is the primary source of energy for all forms of life?

Energy is derived from electron donors and acceptors through oxidation-reduction processes.

What are the main ways cells conserve energy?

Cells conserve energy using electron carriers, ATP, proton motive force, and metabolic pathways.

What are the three main processes that cells use energy for?

Biosynthesis, maintenance, and growth.

What is the difference between exergonic and endergonic reactions?

Exergonic reactions release energy, while endergonic reactions require energy input.

What are the elemental nutrients essential for building biological molecules?

Carbon (C), Nitrogen (N), Oxygen (O), Sulfur (S), Phosphorus (P), and Hydrogen (H).

What are catabolism and anabolism?

Catabolism is the breakdown of molecules for energy, while anabolism is the building of molecules using energy.

What role do enzymes play in metabolism?

Enzymes act as catalysts that speed up biological reactions and increase reaction rates.

What is glycolysis?

Glycolysis is the first phase of glucose oxidation, converting glucose and 2 ATP into 2 pyruvate, 4 ATP, and 2 NADH.

How do organisms generate energy through respiration?

Energy is generated through an electron transport chain (ETC) where electrons are transferred to a terminal electron acceptor.

What is the difference between respiratory and fermentative energy generation?

Respiratory energy generation uses an electron transport chain, while fermentative energy generation directly couples oxidation of organic compounds to energy production.

What are the three central metabolic pathways?

Glycolysis, Pentose Phosphate Pathway (PPP), and Tricarboxylic Acid Cycle (TCA).

What is the significance of NADH and FADH2 in metabolism?

NADH and FADH2 are electron carriers that store energy from chemical transformations.

What is the role of ATP in cellular metabolism?

ATP carries energy and is used by cells to perform work.

What is the energy output dictated by in oxidation-reduction reactions?

The energy output is dictated by the electronegativity of the atoms in a molecule.

What happens during the oxidation of glucose?

Glucose is oxidized to produce energy, CO2, and H2O.

What is the average amount of ATP generated by a human during a lecture?

An average human generates approximately 6.6 lbs of ATP during a lecture.

What are the building blocks of biological polymers?

Amino acids, nucleotides, and fatty acids.

What is the proton motive force?

The proton motive force is the electrochemical gradient generated by the movement of protons across a membrane, used to drive ATP synthesis.

What is the importance of chemical energy in metabolism?

Chemical energy is stored in high-energy molecules like ATP, which is crucial for cellular functions.

How do biochemical reactions relate to biosynthesis?

Biochemical reactions can be reversible, allowing pathways to build precursors for biosynthesis.

What is the function of terminal electron acceptors in respiration?

Terminal electron acceptors, such as oxygen, are essential for completing the electron transport chain and generating energy.

What is the significance of the TCA cycle?

The TCA cycle is crucial for generating reducing power and energy from acetyl-CoA.

What is the relationship between glycolysis and the pentose phosphate pathway?

Both pathways are interconnected and contribute to energy production and biosynthesis.

What is the role of catalysts in metabolic reactions?

Catalysts, such as enzymes, increase the rate of metabolic reactions without being consumed.

What is the primary energy source for chemoorganotrophs?

Chemoorganotrophs derive energy by breaking down organic chemicals like glucose.

What is the role of electron carriers in cellular respiration?

Electrons are transferred onto membrane protein carriers and then onto oxygen.

What is the Chemiosmotic Theory?

It explains how the electron transport system drives protons across the membrane to generate a proton motive force (PMF).

What does PMF stand for?

Proton Motive Force.

What is the formula for calculating Δp?

Δp = Δψ - 60ΔpH.

What does Δψ represent?

Electrical potential, the separation of charge between the cytoplasm and the solution outside the cell membrane.

What does ΔpH indicate?

The log ratio of external to internal chemical [H+].

List four functions of the proton motive force (PMF).

1. ATP production 2. Flagellar rotation 3. Uptake of molecules against a concentration gradient 4. Efflux of molecules against a concentration gradient.

What are the two parts of the F1Fo ATP synthase?

Fo (embedded in the membrane) and F1 (protrudes in the cytoplasm).

What causes the rotation of the Fo subunit in ATP synthase?

Proton flow through the subunit.

What happens during the rotation of the Fo subunit?

It causes the F1 g subunit to turn, changing the conformation of the a and b subunits, which catalyzes ATP synthesis.

What is fermentation?

A metabolic process that occurs when no oxygen is present, regenerating electron carriers and producing a small amount of ATP (2 ATP/glucose).

What is the primary purpose of fermentation?

To regenerate electron carriers.

What are some products of fermentation?

Lactic acid, ethanol, acetic acid, and more.

What is anaerobic respiration?

A process unique to prokaryotes that requires an electron transport chain and directly generates a PMF.

How much ATP can anaerobic respiration produce per glucose?

Up to 38 ATP/glucose.

What is the biological oxygen demand (BOD)?

The amount of O2 required for the microbial decomposition of organic matter in a given sample.

What are great electron donors?

Substances that can donate electrons in metabolic processes, such as glucose.

What are great electron acceptors?

Substances that can accept electrons, such as O2 in aerobic respiration and NO3 in anaerobic respiration.

What is the role of the electron conducting pilus?

It functions as a wire that conducts electricity and transfers electrons over long distances to reach a suitable terminal electron acceptor.

What is bioremediation?

The use of microbial metabolism to clean up pollution.

What is the significance of Geobacter spp. in bioremediation?

They can use metals as terminal electron acceptors to help clean up pollution.

What happens to ATP synthase during fermentation?

ATP is used to run ATP synthase in reverse to generate a PMF for other cellular functions.

What is the energy yield of fermentation?

2 ATP/glucose.

What is the energy yield of aerobic respiration?

Up to 38 ATP/glucose.

What is the energy yield of anaerobic respiration?

~3-30 ATP/glucose.

What do facultative anaerobes do when oxygen is absent?

They switch to anaerobic respiration or fermentation based on available electron acceptors.

What are the two types of microbial metabolism based on energy sources?

Chemoorganotrophs and phototrophs.

What distinguishes chemolithotrophs from other microbial groups?

They use inorganic molecules as electron donors.