Proteins, carbohydrates, lipids, and nucleic acids are important molecules in our body. They work together in different ways inside our cells.

1. Proteins:

   • Made of small units called amino acids.
   • Proteins make up about 15% of the cell’s weight.
   • They have many jobs, like helping reactions happen (called enzymes), sending signals (like hormones), and providing support to the cell’s structure.

2. Carbohydrates:

   • These are the main source of energy and help build structures in the body.
   • For humans, glycogen is the main form of energy storage.
   • We store around 1,500 grams of glycogen in our liver and muscles.

3. Lipids:

   • Lipids are around 10% of the cell’s weight.
   • They are important for making cell membranes and storing energy.
   • The main type of lipid, called phospholipids, creates layers that protect the cell.

4. Nucleic Acids:

   • DNA and RNA are key for keeping our genetic information and making proteins.
   • A single human cell has about 2 meters of DNA, which is tightly wrapped inside the nucleus.

In summary, these macromolecules work together to keep our cells healthy and help with all the processes that happen in our bodies.