What is the relationship between DNA, genes, and chromosomes?
DNA, or deoxyribonucleic acid, is a large molecule or polymer that consists of monomers called nucleotides. The function of DNA is to store hereditary information that can be used to direct the polypeptide sequence of proteins in the body. The genetic code is stored in the DNA.
DNA is the chemical of life and can be found within structures known as chromosomes. Chromosomes can be found in the nucleus of the cell. In diploid organisms, chromosomes can be found in pairs which were inherited from each parent. DNA can direct its own replication, which ensures that when cell division occurs, each new cell will have its own copy of the DNA. When sexually reproducing organisms produce gametes, a haploid number of chromosomes will be included in the gamete so that when fertilization occurs, a new diploid individual is formed.
Discrete units located along the chromosomes are known as genes. The combination of genes that an organism inherits will determine its phenotype.
If we arrange the three terms in order of increasing size, it would be DNA, gene, and chromosome. I have included a link showing the relationship between DNA, genes, and chromosomes.