# Metabolism

All the chemical reactions in a living cell. Catabolic reactions break molecules down and release energy. Anabolic reactions build molecules up and use energy.

Biology (university) · Part 02: Enzymes and energy · Card 1 of 9 · Last updated 2026-10-19

## Analogy

A household budget: income from breaking things down, spending on building things up.

## In practice

Digesting starch into glucose is catabolic. Building muscle protein from amino acids is anabolic.

## Practice

### Flashcards

- **What is the difference between catabolic and anabolic reactions?** Catabolic reactions break molecules down and release energy. Anabolic reactions build molecules and use energy.

## Questions people ask

### What is a metabolic pathway?

A metabolic pathway is a series of linked reactions, where the product of one step becomes the substrate of the next. Each step has its own enzyme. Glycolysis, which breaks glucose into pyruvate, is a pathway of ten steps. Splitting a job into steps lets cells control it carefully.

### Does a faster metabolism mean burning more energy?

In everyday talk, yes. Metabolic rate is the total energy a body uses over time. It depends on body size, muscle mass, age, hormones and activity. Two people of the same weight can have different rates, but the differences are usually much smaller than people assume.

## Related concepts

- [ATP](https://studyvisually.com/learn/science/biology-university/biology-university-part-2/biology-university-part-2-concept-2)
- [Free energy](https://studyvisually.com/learn/science/biology-university/biology-university-part-2/biology-university-part-2-concept-3)
- [Energy coupling](https://studyvisually.com/learn/science/biology-university/biology-university-part-2/biology-university-part-2-concept-4)
- [Redox reaction](https://studyvisually.com/learn/science/biology-university/biology-university-part-3/biology-university-part-3-concept-1)

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