Final answer:
A gene is the unit of DNA on a chromosome that contains the instructions for the creation of a single protein.
Step-by-step explanation:
The unit of DNA on a chromosome that encodes the instructions for a single protein is known as a gene. Each chromosome is composed of DNA that is tightly wound around proteins, and it contains numerous genes which are vital for the creation of proteins. Proteins are essential for almost every function in a cell, influencing the traits of multicellular organisms.
The genes are segments of the DNA molecule that dictate the sequence of amino acids in a protein. In a process called transcription, when a cell requires a specific protein, the corresponding gene is activated, and a messenger RNA (mRNA) copy of the gene's code is made. This mRNA then carries the genetic information to the ribosomes, where the protein is synthesized through a process known as translation. Most genes are responsible for the instructions to create one particular protein, although there may be hundreds to thousands of these genes on a single chromosome.