These 10 animal facts will amaze you. The face of farming and agriculture has changed drastically over the past 100 years. At the beginning of the 20th century, over 70% of the population of the United States lived and worked on farms, but by 2008, the figure had dropped to less that 3%.
During this process, glucose from food is broken down into carbon dioxide and water, and energy is released. The process of releasing energy from food is called respiration, or cellular respiration as it is a series of steps that take place within living cells. It is important to not confuse respiration, or oxidizing glucose, with breathing.
ATP, a high energy molecule, is expended by working cells. Cellular respiration occurs in both eukaryotic and prokaryotic cells. There are three main stages of cellular respiration: glycolysis, the citric acid cycle, and electron transport/oxidative phosphorylation. Glycolysis. Glycolysis literally means splitting sugars. Glucose, a six carbon sugar, is split into two molecules of a three carbon sugar. Glycolysis takes place in the cell's cytoplasm. Glucose and oxygen are supplied to cells by the bloodstream. In the process of glyoclysis, two molecules of ATP, two molecules of pyruvic acid and two high energy electron carrying molecules of NADH are produced. Glycolysis can occur with or without oxygen. In the presence of oxygen, glycolysis is the first stage of aerobic cellular respiration. Without oxygen, glycolysis allows cells to make small amounts of ATP. This process is called anaerobic respiration or fermentation.