Why in cells there are three kinds of RNA molecules, but only one kind of DNA?

DNA is the largest molecule; it cannot leave the nucleus; pores are small. RNA is a small molecule, each performs its own function, providing various functions in the cell while working. Many types of RNA can be synthesized on the DNA matrix at the same time, and they all go to fulfill their functions.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.