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.
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.
The world has lost more than one quarter of its land-dwelling insects in the past 30 years, according to researchers whose big picture study of global bug decline paints a disturbing but more nuanced problem than earlier research.
The decade that just ended was by far the hottest ever measured on Earth, capped off by the second-warmest year on record, two U.S. agencies reported Wednesday. And scientists said they see no end to the way man-made climate change keeps shattering records.