Mutations 6/26/2018 SB2d

SB2d Describe the relationships between changes in DNA and potential appearance of new traits including: Alterations during replication Insertions Deletions Substitutions Mutagenic factors that can alter DNA High energy radiation (x-rays and ultraviolet) Chemical 6/26/2018 SB2d

Mutations Mutations- are changes in the DNA sequence that affect genetic information TYPES Gene mutations- result from changes in a single gene AKA Point Mutation (affects one nucleotide) 3 types: Substitution, Insertion, and Deletion Chromosomal mutation- result from changes in whole chromosomes 6/26/2018 SB2d

Gene mutations Substitution Mutations that affects only one base Equivalent to changing one letter in a sentence, such as, changing the “c” in cat to an “h” Original: The fat cat ate the wet rat. Substitution: The fat hat ate the wet rat. Mistakes are corrected by DNA polymerase if not, DNA is altered. Results in one wrong amino acid 6/26/2018 SB2d

Gene mutations Frameshift Mutations Mutations in which one or more bases are inserted (insertion) or deleted (deletion) Causes reading frame to shift Equivalent to removing the 't' from cat is removed, while keeping the original letter spacing: Original: The fat cat ate the wet rat. Frame Shift: The fat caa tet hew etr at. Frame Shift: The fat cat ate the wet rat a. Results in codons that code for a different amino acid 6/26/2018 SB2d

Gene mutations Insertions Mutations that result in the addition of extra DNA. Insertions can also cause frameshift mutations, and generally result in a nonfunctional protein. Equivalent to inserting xlw for the word ate Original: The fat cat ate the wet rat. Insertion: The fat cat xlw ate the wet rat. 6/26/2018 SB2d

Chromosomal mutations Deletion Mutations that result in missing DNA. These can be small, such as the removal of just one "word," or longer deletions that affect a large number of genes on the chromosome. Deletions can also cause frameshift mutations. Equivalent to deleting the word cat. Original: The fat cat ate the wet rat. Deletion: The fat ate the wet rat. Results in a severely altered or nonfunctional protein 6/26/2018 SB2d

Chromosomal mutations Duplication Mutation that produces an extra copy of all or part of a chromosome. Usually no affect on the organism 6/26/2018 SB2d

Chromosomal mutations Inversion Mutations in which an entire section of DNA is reversed. A small inversion may involve only a few bases within a gene, while longer inversions involve large regions of a chromosome containing several genes. Original: The fat cat ate the wet rat. Insertion:The fat tar tew eht eta tac. Results in DNA alterations 6/26/2018 SB2d

Chromosomal mutations Translocation Mutations that occur when part of one chromosome breaks off and attaches to another, nonhomologous chromosome Can affect gene function 6/26/2018 SB2d

Body cell vs. Sex cell Mutations Mutations in body cells do not affect offspring. Affect only the organism in which they occur Mutations in sex cells can be harmful or beneficial to offspring. Source of genetic variation Natural selection often removes mutant alleles from a population when they are less adaptive. 6/26/2018 SB2d

Benefits/Causes of Mutations Replication errors can cause mutations. Mutagens, such as UV ray, X rays, gamma rays and chemicals, can cause mutations. Some cancer drugs use mutagenic properties to kill cancer cells. Beneficial: Can produce proteins with new or altered functions that can be useful to organisms Polyploid plants are larger and stronger than diploid plants. 6/26/2018 SB2d