Mutations

Mutations are changes to the base pair sequence of the genetic material of an organism.

Mutations can be caused by copying errors in the genetic material during cell division, by exposure to ultraviolet or ionizing radiation, chemical mutagens, or viruses.

Multicellular Mutations

Germ line mutations – can be passed on to descendants

Somatic mutations – cannot be transmitted to descendants

Types of Mutations

Point mutation – where only one base in the gene is copied incorrectly during DNA replication. This would be an error of the DNA-building enzyme, DNA polymerase.

Types of Mutations

Point mutation example:(A) Substitution – exchanges one base for another

example: change in a single “chemical letter” such as switching an A to a G

C T G G A GC T G G G G

Types of Mutations

Frameshift – Since protein-coding DNA is divided into codons three bases long, insertions and deletions can alter a gene so that its message is no longer correctly read or translated.

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Types of Mutations

Frameshift mutations example:(A) Insertion – extra base pairs are inserted into a new place in DNA

C T G G A GC T G G T G G A G

Types of Mutations

Frameshift mutations example:(B) Deletion – a section of DNA is lost, or deleted

C T G G A GC T A G