2 What is a mutation?A change in the base sequence of DNA
3 What causes mutations? Mistakes in replication (spontaneous) Mistakes in base pairsEnvironmental factors (mutagens)High energy radiation (X rays, UV rays)Chemicals (asbestos, cyanide, formaldehyde)High temperature
4 A mutagen Any agent that causes a change to the DNA sequence High energy mutagens (radiation) break the DNA strands apart causing deletions or substitutionsHighly reactive mutagens (chemical) interact with the DNA usually causing substitutions
5 Mutations in reproductive cells Changes a sequence of nucleotides in a geneMay produce a new trait for the offspring
6 Mutations in body cells Change in the nucleotide sequence only effects the individual and will not be passed down to the offspringi.e. Cancer, which effects genes that control cell division in mitosis
7 Types of Mutations Point mutations Frameshift mutations Chromosomal mutationsDeletionInsertionInversionTranslocation
8 Point mutationsA simple change in a single nucleotide base or “letter” of the gene sequence
9 Point mutations Original: The fat cat ate the wee rat. Point Mutation: The fat hat ate the wee rat(changing the r in cat to the h in hat).This change alters the meaning of the instructions significantly. In DNA, switching one base in the DNA sequence to a different base can change the protein that the gene makes.
10 Frame-shift mutations When one or more bases are added or deleted to the DNA strand.It shifts the reading of mRNA codons by one base
11 Frame-shift mutations Original: The fat cat ate the wee rat.Frame Shift: The fat caa tet hew eer at.(the “t” from cat is removed)This type of mutation can make the DNA code meaningless and often results in a shortened protein.
13 Deletions Occur when a part of the chromosome is left out. These can be small, such as the removal of just one "letter" or long enough to affect a large number of genes next to one another on the chromosome.Deletions can also cause frame-shift mutations.
14 Deletions Original: The fat cat ate the wee rat. Original: The fat cat ate the wee rat.Deletion: The fat ate the wee rat.(deletion eliminated the word “cat.”)