Point mutation is a type of genetic mutation in which one of the base pairs in a DNA sequence gets changed. This may be caused due to insertion or deletion. 

Most point mutations occur during DNA replication where single point mutation in the sequence can alter the entire DNA sequence. While most mutations occur spontaneously during DNA replication, the rate of mutation increases on exposure to physical or chemical mutagens. Physical mutagens that cause point mutation include extreme heat or radiation from X-rays and UV rays. Chemical mutagens include molecules that misplace base pairs.