Aerobic respiration on the cellular level occurs in the cell's mitochondria, according Georgia State University. Respiration transforms pyruvate into adensoine triphosphate through the TCA cycle in mitochondria. The TCA cycle, also known as the Krebs cycle, uses enzymes to transport electrons among water, oxygen, carbon and other atoms.
Respiration starts when glucose enters the cell membrane. Glucose changes into pyruvate through the process of glycolysis in the cell's cytoplasm. Glycolysis occurs in 10 basic steps when carbon, hydrogen and oxygen atoms interact with phosphorus in the cell, according to State University of New York.
Once in mitochondria, pyruvate turns into coenzyme A. SUNY indicates this enzyme becomes two types of ions in the mitochondria that transport electrons among various atoms to make ATP. ATP provides energy for the cell.
CliffsNotes explains that oxygen is required for cellular respiration, and carbon dioxide is the waste product. The basic chemical formula for the four steps of cellular respiration involves one molecule of glucose for six molecules of oxygen to produce six molecules of water, six molecules of carbon dioxide and energy. The scientific designation is "C6H12O6 + 6O2 ----> 6H2O + 6CO2 + energy."
Typical animal cells have 1,000 to 2,000 mitochondria each. Fat cells have many more mitochondria because they store energy. Muscle cells have a lot of mitochondria since muscles need a lot of ATP to function, according to GSU.