What is a small section of DNA that codes for the production of a specific protein called?

A small section of DNA that codes for the production of a specific protein is called a gene. Genes are fundamental units of heredity and play a crucial role in determining the traits of an organism. Each gene contains the instructions, or sequences, needed for synthesizing proteins, which perform numerous functions within biological systems, such as catalyzing biochemical reactions, providing structural support, or regulating cellular processes.

The other options refer to different concepts in genetics. A chromosome, for example, is a long, continuous strand of DNA that contains many genes and is found in the nucleus of eukaryotic cells. An allele is a variant form of a gene that can result in different traits. A codon, on the other hand, is a sequence of three nucleotides in DNA or RNA that corresponds to a specific amino acid or a stop signal during protein synthesis.