The sudden change in a gene structure or chromosome number in an organism likely to cause an inheritable change in the phenotype is known as

The sudden change in a gene structure or chromosome number in an organism that is likely to cause an inheritable change in the phenotype is known as mutation. A mutation is a permanent alteration in the DNA sequence that makes up a gene. This can occur spontaneously or as a result of exposure to mutagens such as radiation, chemicals or viruses. Mutations can affect the phenotype of an organism by changing its physical, biochemical or behavioral characteristics. Some mutations can be beneficial, neutral, or harmful to an organism's survival and reproductive success, depending on the environmental conditions. Mutations can also be passed down to offspring through the genetic material, making them inheritable.