Final answer:
The step of translation that involves mRNA codons being read and amino acids forming is called elongation.
Step-by-step explanation:
The step of translation that involves mRNA codons being read and amino acids forming is called the elongation step. During elongation, the ribosome moves along the mRNA, reading the codons and bringing in the appropriate amino acids.
The tRNAs with complementary anticodons bind to the codons on the mRNA, forming peptide bonds between the amino acids, and the polypeptide chain grows.