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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.

Mystery of the Missing Tusks

This activity explores images of elephants with and without tusks, which serve as phenomena for learning about selection and human impacts on the frequency of traits within populations.

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.

Nutrient Cycling in the Serengeti

In this activity, students engage with an example from the Serengeti ecosystem to illustrate the exchange of nutrients between plants, animals, and the environment. 

Red Tattoo

This activity explores an image of tattoo ink particles inside cells, which serves as a phenomenon for learning about the structure and color of human skin.

Coloration in Vertebrates

This activity explores images of animals with a mutation that affects coloration, which serve as phenomena for learning about skin color genetics and evolution.

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.

Photosynthesis

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

Human Origins

This interactive module allows students to examine fossils of early humans and compare them to modern primates.

Winogradsky Column: Microbial Ecology in a Bottle

This interactive module consists of a virtual Winogradsky column, which can be used to explore the diversity of microbes, microbial metabolic strategies, and geochemical gradients found in sediments.