12-4 Mutations Baker Block 1 Pgs 307 - 308

Mutations Mutations are changes in the genetic material. Sometimes cells make mistakes copying their DNA and insert an incorrect base or even skip a base.

Two types of mutations: Gene Mutations – these make changes in a single gene. Chromosomal Mutations – these make changes to an entire chromosome.

Gene Mutations Point Mutations – insertion, substitution, or deletion of a few nucleotides results in a point mutation. Frameshift Mutations – In the case of insertion and deletion these can cause the bases that are being read in sets of three to shift and the result could be a new amino acid. Figure 12-20 – pg 307. This can cause a protein to not be able to perform its intended function.

Point Mutation:

Describe substitution, insertion, & deletion. Figure 12-20/page 307 Substitution – the wrong nucleotide is used and this changes a single amino acid. Insertion – addition of a nucleotide in DNA. This changes EVERY amino acid after the insertion. Deletion – removal of a nucleotide in DNA. Changes EVERY amino acid after the insertion.

Chromosomal Mutations This includes changes in the number or structure of the chromosomes. Four types: deletions, duplications, inversions, and translocations.

How significant are mutations? Most are neutral – little or no effect. Some provide increased genetic variability and prove to be highly beneficial. Some can cause genetic disorders – sickle cell, and cystic fibrosis. Harmful mutations are associated with some types of cancer.

Plant Breeders and Mutation There are beneficial mutations that are to the benefit of the farmer that is growing the specific crop. Polyploidy – a condition in which an organism has extra sets of chromosomes. These extra sets of chromosomes can cause a plant to grow bigger and stronger.