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This animation shows two examples of how the cell uses energy from ATP. It is the sixth of six animations about cellular respiration. These animations bring to life the molecular engines inside mitochondria that generate ATP, the main source of chemically stored energy used throughout the body.

This animation shows how the pyruvate dehydrogenase enzyme complex converts pyruvate into acetyl-CoA. It is the second of six animations about cellular respiration.

This animation shows how glycolysis converts glucose into pyruvate through a series of enzyme reactions. It is the first of six animations about cellular respiration. These animations bring to life the molecular engines inside mitochondria that generate ATP, the main source of chemically stored energy used throughout the body.

This animation shows how the proton gradient across the mitochondrial membrane powers the ATP synthase enzyme to make ATP. It is the fifth of six animations about cellular respiration. These animations bring to life the molecular engines inside mitochondria that generate ATP, the main source of chemically stored energy used throughout the body.

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 fourth of six animations about cellular respiration. These animations bring to life the molecular engines inside mitochondria that generate ATP, the main source of chemically stored energy used throughout the body.

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 third of six animations about cellular respiration. These animations bring to life the molecular engines inside mitochondria that generate ATP, the main source of chemically stored energy used throughout the body.

This film explores how life recovered after an asteroid wiped out the dinosaurs and how those events shaped the diversity of plants and mammals on Earth today.

This interactive module allows students and educators to build models that explain how the Earth system works. The Click & Learn can be used to show how Earth is affected by human activities and natural phenomena.

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

This model shows the skull of Tiktaalik, a vertebrate that existed about 375 million years ago and had features of both fish and tetrapods (four-limbed animals).

This model shows the skeleton of Tiktaalik, a vertebrate that existed about 375 million years ago and had features of both fish and tetrapods (four-limbed animals).

This model shows the pectoral fin bones of Tiktaalik, a vertebrate that existed about 375 million years ago and had features of both fish and tetrapods (four-limbed animals).