Understanding Mutations: Types and Implications in Genetics
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Learn about mutations - changes in DNA sequence, their types (gene, frameshift, chromosome), and mutagenesis. Explore base substitutions, silent, missense, and nonsense mutations. Understand chromosome mutations like deletion, duplication, inversion, translocation, and nondisjunction.
Understanding Mutations: Types and Implications in Genetics
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Presentation Transcript
Mutations A change in the nucleotide sequence of DNA Ultimate source of genetic diversity Gene vs. Chromosome
Gene Mutations • Base Substitution – replacement of one nucleotide with another, change to final protein is minimal – 1 amino acid or no change at all • Silent mutation – base change codes for the same amino acid • Missense mutation – base change codes for a different amino acid • Nonsense mutation – base change codes for a stop codon
Gene Mutation • Frameshift Mutation – insertion or deletion of a nucleotide; changes the reading frame of the mRNA codons; can result in different amino acids from the point of the mutation on; major change to the amino acid sequence of the protein
Chromosome Mutations • Mutations that effect multiple genes • Deletion – loss of part of chromosome • Duplication – doubling of part of a chromosome • Inversion – changing the gene order of a chromosome • Translocation – crossing over between nonhomologous chromosomes • Nondisjunction – failure of homologous chromosomes or sister chromatids to separate during meiosis or mitosis
Mutagenesis The creation of a mutation Spontaneous mutations – mistakes in replication Mutagen – chemical, physical, or biological agent causes the mistake