How do cells convert the energy provided in food into energy that is usable by the cell?

Question

How do cells convert the energy provided in food into energy that is usable by the cell?

Answer 1

The body takes the core elements of food (carbohydrates, lipids, nucleic acids, or amino acids etc.) and breaks them down into smaller subunits and it uses the oxidation of these reduced molecules for energy. If we look at glucose, a main energy source, it enters into glycolysis where it is broken down into smaller pieces and creates the main energy currency of the body ATP. This is not where a majority of ATP is made however. The 3 carbon molecules (pyruvate) enters into the citric acid cycle where it creates more ATP, but more importantly it creates reduced NADH and FADH2. These are important because they enter into the 3rd part of energy creation - the electron transport chain and oxidative phosphorylation. The NADHs and FADH2s spin off their electrons into specialized proteins and in doing so release hydrogen ions into the intermembrane space in the mitochondria. This hydrogen pileup creates a gradient which it desires to run down. The hydrogen ions finally pass back into the mitochondrial matrix when they pass through the ATP synthase. They reduces molecular Oxygen (O2) and drive a pump that puts inorganic phosphates onto ADP's. This creates the largest amount of ATP in the body.

ATP is important because the phosphate bonds are very strong. When these bonds are oxidized they release a large amount of energy and drive processes of the body.

Answer 2

The mitochondrion, sausage-shaped organelles would oxidise the food substances during aerobic respiration to produced adenosine triphosphate energy, which is used especially for active transport, when materials have to be diffused from a lower concentration to a higher concentration.