--- title: "Metabolic Diversity: Choosing an Electron Donor and Acceptor" description: "Microbes are classified by where they get carbon, where they get energy and what they pass electrons to at the end. The energy available depends on the gap between donor and acceptor, which is why oxy" canonical: https://lightmysky.com/learn/science/metabolic-diversity-choosing-an-electron-donor-and-acceptor-mt__2yCr9OSIn source: https://lightmysky.com/learn/science/metabolic-diversity-choosing-an-electron-donor-and-acceptor-mt__2yCr9OSIn.md retrieved: 2026-09-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Metabolic Diversity: Choosing an Electron Donor and Acceptor Microbes are classified by where they get carbon, where they get energy and what they pass electrons to at the end. The energy available depends on the gap between donor and acceptor, which is why oxygen respirers outgrow the alternatives when oxygen is present. Subject: Science · Area: Microbiology · Ages 19 to 20 Page: https://lightmysky.com/learn/science/metabolic-diversity-choosing-an-electron-donor-and-acceptor-mt__2yCr9OSIn ## Ready when they can - Classifies an organism from its carbon source, energy source and terminal acceptor. - Ranks acceptors by the energy yield they allow and explains the ranking. - Predicts which metabolism dominates as a sediment loses oxygen with depth. ## Lesson: Who breathes what, and who wins Imagine sorting microbes the way you sort lunchboxes. Ask where carbon comes from: air gas or ready made organics. Ask where energy comes from: light or chemicals. Then ask what catches electrons at the end. Those three answers fix the lifestyle completely. Now rank the catchers the way athletes rank medals. Oxygen accepts most willingly, then nitrate, then sulfate and carbon dioxide last. The wider the gap between giver and catcher, the more energy each fuel molecule banks. That sliding scale is why oxygen users outgrow the rest wherever oxygen reaches. **Example.** Picture the mud under a pond sorted by depth for you. Near the top the oxygen users grow fastest on the full payoff. Below them come the nitrate users, and deep down in the oxygen free dark sit the sulfate breathers and methane makers. Read the oxygen profile and you predict the stack. **Tip.** Two small extras complete your map. Without an outside catcher, cells dump electrons back onto their own waste just to keep going, and most fuel energy stays locked inside: tiny yield. With a catcher, electron flow pumps a gradient whose return through the synthase mints the energy coins. **Recap.** You read the carbon, energy, and final catcher to predict who wins each layer. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Controlling Growth: What Sterile Means and How It Is Achieved](https://lightmysky.com/learn/science/controlling-growth-what-sterile-means-and-how-it-is-achieved-mt_j1kqpjUMzk) - [Anaerobic Routes and the ATP Yield Compared](https://lightmysky.com/learn/science/anaerobic-routes-and-the-atp-yield-compared-mt_LBZ4laMfqb) - [Standard Electrode Potentials and Predicting Redox Reactions](https://lightmysky.com/learn/science/standard-electrode-potentials-and-predicting-redox-reactions-mt_LDI10CjoAI) ## Opens up - [Metabolic Engineering: Redirecting Flux Through a Production Host](https://lightmysky.com/learn/science/metabolic-engineering-redirecting-flux-through-a-production-host-mt_fjz3EA-dDa) - [Virus Structure and Classification by Genome Type](https://lightmysky.com/learn/science/virus-structure-and-classification-by-genome-type-mt_u2-ecQEwwn)