Which stage in the process of making a protein should be inserted into step 2?
1. dna in the nucleus contains information to code for a protein.
2.
3. rna reaches the ribosome.
4. a different kind of rna decodes the information and assembles the building blocks of the protein.
5. the protein is then transported to its proper destination.

The second step is:

Genetic information for synthesis of the specific protein is  transcribed on to mRNA.

This process is called transcription and takes place in the nucleus.   With the help of an enzyme called RNA polymerase, a particular segment of DNA is copied onto a strand of RNA which is called messenger mRNA because it will carry this coded information from the nucleus and into the cytoplasm to the ribosomes for translation. mRNA is therefore a kind of "messenger."

In the ribosomes the information is translated or "decoded" and with the help of another type of RNA called transfer RNA  (tRNA), amino acids are assembled according to the decoded information to make the specified protein.