Final answer:
The part of DNA that encodes a protein is a gene, which is the basic unit of heredity consisting of DNA sequences that contain the instructions for protein synthesis.
Step-by-step explanation:
A gene is a segment of DNA or RNA in some organisms that codes for a single polypeptide chain or RNA molecule. In simpler terms, genes are the basic functional units of heredity, consisting of DNA sequences that contain the instructions for making proteins, which are crucial for the various functions of a cell. Chromosomes, which are made up of DNA and proteins, may contain hundreds or thousands of genes, arranging them in a specific order that determines an organism's traits by encoding the necessary proteins.
The genetic code within these genes is read in series of three-letter codes known as codons, representing amino acids, the building blocks of proteins. Understanding the relationship between genes and proteins is essential because proteins perform most life functions and even make up the majority of cellular structures.