1. Carbohydrates: These are sugars and starches. They are the primary source of energy for cells and are also used for structural purposes. Examples include glucose, fructose, starch, and cellulose.
2. Lipids (fats and oils): These are hydrophobic (water-repelling) molecules that serve as energy storage, insulation, and components of cell membranes. Examples include triglycerides, phospholipids, and steroids.
3. Proteins: These are complex polymers made up of amino acids. They play a wide variety of roles in the body, including enzymes, structural components, and hormones. Examples include enzymes, antibodies, and collagen.
4. Nucleic acids: These are responsible for storing and transmitting genetic information. Examples include DNA and RNA.
These four molecules are found in all living organisms, from the simplest bacteria to the most complex animals. They are essential for life, and their structure and function are closely intertwined.
While these are the main four, some might also consider water to be "omnipresent" as it is essential for all biological processes and makes up the majority of the mass of most organisms.
It's important to remember that life is diverse and there are exceptions to every rule. There are some organisms that may not have all four of these molecules in the same way, but they will still have some form of these molecules or their equivalents.
