1 - 12 of 81 results
Citric Acid Cycle

This animation shows the reactions of the citric acid cycle, which splits off carbon atoms and generates energy-rich reduced forms of cofactor molecules. It is the first of three animations about cellular respiration.

Electron Transport Chain

This animation shows how the enzyme complexes of the electron transport chain harvest energy from cofactor molecules to pump protons across the mitochondrial membrane and establish a chemical gradient. It is the second of three animations about cellular respiration.

ATP Synthesis

This animation shows how the proton gradient across the mitochondrial membrane powers the ATP synthase enzyme to make ATP. It is the third of three animations about cellular respiration.

Modeling the Structure of DNA

In this activity, students build a paper model of DNA and use their model to explore key structural features of the DNA double helix. This activity can be used to complement the short film The Double Helix.

Sodium Channel Evolution in Electric Fish

This activity guides the analysis of a published scientific figure from a study that investigated how gene duplication contributed to the evolution of electric fish.


This multipart animation series explores the process of photosynthesis and the structures that carry it out.

Sex Verification Testing of Athletes

This interactive module explores the biology of sex determination and development in humans, set against the backdrop of the different sex testing policies implemented throughout sports history.

Cystic Fibrosis Mechanism and Treatment

This animation shows how mutations in an ion channel protein lead to the genetic disease cystic fibrosis. The animation also discusses how research on this protein has been used to develop treatments for the disease.

Sleep Clears β-amyloid from the Brain

This activity analyzes a published scientific figure from a study that investigated the biological importance of sleep. In this study, scientists tested whether sleep plays a role in removing harmful substances from the brain.

Written in Chalk

This activity explores images of chalk formations and coccolithophores, which serve as phenomena for learning about the interactions between biological and geological processes.