There are two basic types of mutations Gene mutations mutations that produce changes in a single gene Chromosomal mutations mutations that produce changes in whole chromosomes Gene mutations ID: 1042738
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1. Types of mutations Mutations are changes in the genetic materialThere are two basic types of mutations:Gene mutations - mutations that produce changes in a single geneChromosomal mutations - mutations that produce changes in whole chromosomes
2. Gene mutations Point mutations:Involves changes in one or a few nucleotides (they occur at a single point in the DNA sequence)They can be:SubstitutionsInsertions Deletions
3. Substitutions One base is changed to anotherSubstitutions usually only affect a single amino acid
4. Insertions and DeletionsA base is either inserted or removed from the DNA sequenceIf a nucleotide is added or deleted, the bases are still read in groups of three, so every codon after is changedThese types of mutations cause Frameshift mutationsCan cause major changes to the protein, to the point where it can’t perform its normal function
5. Chromosomal mutations Involve the chromosomal changes in the number or structure of chromosomesCan change the locations of genes on chromosomes, and the number of copies of some genesFour types:DeletionsDuplicationsInversionsTranslocations
6. Duplications and DeletionDuplication (Nondisjunction): The failure of a chromosome to separate from its homologue during meiosisOne gamete receives an extra copy of a chromosome and the other lacks itDeletion:Loss of a piece of a chromosome
7. Translocations and InversionsTranslocation:When a chromosome piece breaks off and reattaches to another, nonhomologous chromosomeInversion:Chromosome segment breaks off and then reattaches in reverse orientation to the same chromosome
8. Significance of Mutations Most mutations are neutral (they have little or no effect)Mutations that cause dramatic changes in protein structure or gene activity can be very harmfulMutations are a source of genetic variability in a speciesPolyploidy- a mutation where an organism has an extra set of chromosomesPolyploid plants are often larger and stronger