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What are we learning about?

* Hundreds of chemical reactions occur simultaneously in every living cell. 

* The entire set of them are collectively known as metabolism .

* in some reactions, complex molecules are broken down to produce energy

* in other reactions, energy is used to build up complex molecules.


From Greek ἁνά, “upward” and βάλλειν, “to throw”

All the chemical pathways in which cells bond smaller molecules together to make macromolecules (larger ones.)

The energy source is another set of processes, catabolism (see below)

Anabolism is used to

create news cells

build muscles and tissues.

grow and mineralize bone



From the Greek κάτω kato, “downward” and βάλλειν ballein, “to throw”

All the chemical pathways in which cells break down large molecules into smaller ones.

Cells gain energy from the breakdown, or create smaller pieces, which become building materials in anabolism.

Catablism is used to:

break proteins down into amino acids

break DNA molecules down into individual nucelotides

convert sugar into ATP and other small organic molecules

Another way to show these metabolic pathways:

anabolic and catabolic metabolism

BBC Bitezie revisions

Endocrine hormones regulate our metabolism

Hormones can be classified as anabolic or catabolic.

Anabolic hormones are the anabolic steroids, which stimulate protein synthesis and muscle growth, and insulin.

Catabolic hormones include

cortisol (breaks down large molecules into simple sugars, for quick energy)

glucagon (breaks down large molecules into glucose and fatty acids)

adrenaline – increases blood flow to muscles, output of the heart, blood sugar level.

Our article on the endocrine hormone system.


What does metabolism look like inside a cell? Here’s a simplified view:

Metabolism anabolism catabolism

Image from An Introduction to Nutrition, v. 1.0. 2012books.lardbucket.org/books/an-introduction-to-nutrition


Metabolic map

This is a metro-style map of the metabolism of most life on Earth.

Metabolism pathways Wikimedia

Image by Bert Chan, Hong Kong, via Wikimedia. https://www.behance.net/bertchan

Interactive Metabolic Pathways Map – New Edition | Sigma-Aldrich


Related articles

Scaling-and-biophysics: As animals get larger and larger, how would their metabolism need to change?

Cellular respiration: An introduction

Interactive metabolism maps or apps

Metabolic pathways from Learn.Genetics

Clickable metabolic map from metabolicpathways.teithe.gr

Wiley college textbook step-by-step animations

Virtual Metabolic Human

Roche biochemical pathway online map

Learning Standards

MS-LS1-3.  Use argument supported by evidence for how the body is a system of interacting subsystems composed of groups of cells. Emphasis is on the conceptual understanding that cells form tissues and tissues form organs specialized for particular body functions. Examples could include the interaction of subsystems within a system and the normal functioning of those systems.

MS-LS1-7. Develop a model to describe how food is rearranged through chemical reactions forming new molecules that support growth and/or release energy as this matter moves through an organism. Emphasis is on describing that molecules are broken apart and put back together and that in this process, energy is released.


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