A mutation is a permanent change in the DNA sequence of a gene. Mutations are caused when Mistakes occur while a cell copies its DNA in preparation for cell division. There are several different types of mutations that can possibly occur. First off, there are point mutations, which is a simple change in one base of the gene sequence. In a frame-shift mutation, one or more bases are inserted or deleted. Mutations that result in missing DNA are known as deletions. On the contrary, Mutations that result in extra DNA are called insertions. Finally, in an inversion, an entire section of DNA is reversed. The effects of genetic mutations can always vary. In some cases, they can be somewhat minor, such as a cleft lip, which in most countries can be fixed relatively easily. Mutations however, can also be very serious at times. Mutations are the cause of disorders such as downs syndrome, Hemophilia, Tay Sachs disease, and many more.
Mutation Animation

Mutation video
Mutation graphic
Causes of Mutations