What is the relationship between genome size and gene number in different organisms?

Genome size: It refers to the amount of DNA contained in a haploid genome expressed either in terms of the number of base pairs, kilobases, or megabases, or as the mass of DNA in picograms.

Gene number: A gene is the basic physical and functional unit of heredity. Some genes act as instructions to make molecules called proteins.

There is no straight forward relationship between genome size and organism complexity due to size variability of the facultative part of genome. But generally, an organism’s complexity is not directly proportional to its genome size.

Some single-cell organisms have much more DNA than humans. Gene number and gene size are correlated. Genome size evolves independently of organismal complexity and gene number.