biology

Wolfe cycle

Wolfe cycle is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Wolfe cycle rather than just read about it. In short: The Wolfe Cycle is a methanogenic pathway used by archaea; the archaeon takes H2 and CO2 and cycles them through a various intermediates to create methane. The Wolfe Cycle is modified in different orders and classes of archaea as per the resource availability and requirements for each species, but it retains the same basic pathway.

Key takeaways

Wolfe cycle belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Wolfe cycle to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Wolfe cycle from memory before moving on to harder problems.

Reference excerpt

The Wolfe Cycle is a methanogenic pathway used by archaea; the archaeon takes H2 and CO2 and cycles them through a various intermediates to create methane. The Wolfe Cycle is modified in different orders and classes of archaea as per the resource availability and requirements for each species, but it retains the same basic pathway. The pathway begins with the reducing carbon dioxide to formylmethanofuran. The last step uses heterodisulfide reductase (Hdr) to reduce heterodisulfide into Coenzyme B and Coenzyme M using Fe4S4 clusters. Evidence suggests this last step goes hand-in-hand with the first step, and feeds back into it, creating a cycle. At various points in the Wolfe Cycle, intermediates that are formed are taken out of the cycle to be used in other metabolic processes. Since intermediates are being taken out at various points in the cycle, there is also a replenishing (anaplerotic) reaction that feeds into the Wolfe cycle, this is to regenerate necessary intermediates for the cycle to continue. Overall, including the replenishing reaction, the Wolfe Cycle has a total of nine steps. While Obligate CO 2 {\displaystyle {\ce {CO2}}} reducing methanogens perform additional steps to reduce CO2 to CH 3 {\displaystyle {\ce {CH3}}} .

Discovery In 1971, in a review published by Ralph Stoner Wolfe, information regarding methanogenesis in M. bryantii was published. At the time, the only thing known about this process was that Coenzyme M was involved. In addition, methanogenesis was thought to follow a linear pathway. It was not until 1986 that the reduction of CO 2 {\displaystyle {\ce {CO2}}} to CH 4 {\displaystyle {\ce {CH4}}} was proposed to occur in a cycle when it was shown that Steps 8 and 1 are coupled.

Steps The Wolfe Cycle follows multiple pathways, depending on the microbe. Below are generalized steps in the Wolfe Cycle.

References

Illustrations

Worked examples

Example 1 — a first encounter with Wolfe cycle

Start with the simplest possible case. Write down what Wolfe cycle claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Wolfe cycle before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Wolfe cycle ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Wolfe cycle

In research: Wolfe cycle appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Wolfe cycle in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Wolfe cycle is common in secondary-school and first-year university syllabi. It links to neighbouring topics Anaerobic digestion, Archaea biology, Metabolic pathways, so understanding it makes those chapters shorter.
In everyday life: Look for Wolfe cycle outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Wolfe cycle in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Wolfe cycle means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Wolfe cycle out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Wolfe cycle in simple terms?

Why does Wolfe cycle matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Wolfe cycle?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Wolfe cycle.