Transcript Mutations
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 G was replaced by A Point Mutation mRNA: AUG-AAG-UUU-AGC-GCA-UUG-UAA 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 Deletion • ABCDE FGH ABCBCDE FGH Insertion • ABCDE FGH ADCBE FGH Inversion • ABCDE FGH WXY Z WXABCDE FGH Translocation Y Z Questions?