What do we now understand that genes encode for primarily?

Genes are primarily understood to encode for proteins, which are made up of polypeptide chains. When a gene is expressed, it undergoes transcription to produce messenger RNA (mRNA), which is then translated into a specific sequence of amino acids. These amino acids are linked together to form a polypeptide chain, which then folds into a functional protein.

While polypeptide chains are indeed the direct result of gene expression and are critical in the process of building proteins, it’s important to highlight that the end goal of most genes is the synthesis of proteins. Therefore, the most comprehensive and correct way to describe what genes primarily encode for is proteins. The polypeptide chain is an intermediate step in that process, as proteins are made up of one or more polypeptide chains.