Mutations

Mutations A section of DNA on a chromosome that directs the making of a specific protein is called a gene Genes control the traits inherited by an organism If a change occurs in a gene or chromosome, a trait of that organism may be changed Any permanent change in a gene or a chromosome of a cell is called a mutation

Gene mutations Point mutation- A change in a single base pair in DNA Causes a change in a single amino acid in the protein for which the gene codes Example: Normal mRNA: AUG-AAG-UUU-GGC-GCA-UUG-UAA Point Mutation mRNA: AUG-AAG-UUU-AGC-GCA-UUG-UAA G was replaced by A

Gene Mutations continued Frameshift mutation- when a single nitrogen base is added to or deleted from a DNA strand Addition or deletion- of a base causes the sequence of amino acids on the strand to change= formation of different protein

Chromosomal mutations Occur when parts of chromosomes are broken off and lost during mitosis and meiosis. Also occur when chromosomes break and rejoin incorrectly. Deletion- when part of a chromosome is left out Insertion- when a part of a chromatid breaks off and attaches to its sister chromatid Inversion- takes place when a part of a chromosome breaks out and is reinserted backwards Translocation- occurs when a part of a chromosome breaks off and is added to a different chromosome

Examples of Chromosomal Mutations ABCDE FGH ABCE FGH ABCDE FGH ABCBCDE FGH ABCDE FGH ADCBE FGH ABCDE FGH WXABCDE FGH Deletion Insertion Inversion Translocation WXY Z Y Z

Questions?