Cellular respiration is the sequence of reactions and processes that cells use to produce ATP, but the processes inside of the mitochondria depend on oxygen. When oxygen is unavailable, anaerobic conditions, cells face a critical problem. Glycolysis, the first stage of respiration, requires a steady supply of NAD⁺ to keep running. NAD⁺ can be regenerated through the electron transport chain, but this requires oxygen. When oxygen is not present, the cell cannot regenerate NAD⁺ using the...

Every time you sprint for a bus, think through a tough problem, or even just breathe, your cells are working hard to keep you powered with cellular energy. The fuel behind all of it? A molecule called ATP. And the first step in making it, no matter if you are a bacteria or a human, is a process called glycolysis. Glycolysis is where cellular respiration begins. It happens right in the cytosol, the fluid that fills your cells, and it doesn't need oxygen to run. That makes it one of the most...

A description of the four rules of significant figures and how to use them.