A segment of DNA capable of synthesizing a specific protein is called a gene.

Here's why:

* Genes are the fundamental units of heredity. They contain the instructions for building and maintaining an organism.

* Proteins are essential for virtually every function in the body. They act as enzymes, structural components, hormones, and more.

* Transcription is the process where a gene's DNA sequence is copied into a messenger RNA (mRNA) molecule.

* Translation is the process where the mRNA molecule is used to assemble a specific protein from amino acids.

So, a gene contains the genetic code that determines the sequence of amino acids in a protein, ultimately dictating its structure and function.