Summary
Highlights
Metabolism is defined as a series of chemical reactions within our bodies that sustain life. This video aims to break down this broad definition. Life's requirements, such as maintaining body temperature, reproduction, and growth, depend on the body's ability to utilize four essential biomolecules: proteins, fats, carbohydrates, and nucleic acids (like DNA and RNA). These biomolecules perform various life-sustaining reactions within our cells.
We obtain these biomolecules by eating food. However, the biomolecules in food from other organisms are not always in the exact configuration our bodies prefer. Through digestion, our bodies break down food into the smallest component parts of these biomolecules: amino acids from proteins, fatty acids from fats, glucose from carbohydrates, and nucleotides from nucleic acids.
Building molecules back up (anabolism) requires energy. This energy comes from food. The energy currency of the cell is ATP (adenosine triphosphate). When ATP is broken down into ADP, it releases chemical energy used to fuel anabolic processes. To continue this cycle, ADP must be regenerated into ATP. Certain food subunits, primarily glucose and fatty acids (and sometimes amino acids), act as fuels that are broken down further to produce the energy needed to convert ADP back to ATP. This process is called cellular respiration, which is a catabolic process.
Catabolism fuels anabolism; the energy extracted from breaking down molecules through processes like cellular respiration is used to build molecules. These two processes are tightly regulated in our bodies, often through hormones, which determine whether the body should be in a catabolic or anabolic state.
Metabolism involves a delicate balance between breaking down molecules (catabolism) and building them back up (anabolism). The broken-down components are like LEGO pieces that our bodies reconstruct into the specific proteins, fats, carbohydrates, and nucleic acids needed. Catabolism refers to the breaking down process, while anabolism refers to the building up process.