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12-4 Mutations Are all mutations bad? Objective: Contrast gene mutations & chromosomal mutations What is a mutation? • Changes in genetic information. • Usually occurs in DNA replication. Kinds of Mutations • Gene Mutations: only changes 1 gene – Point Mutations occur when 1 or a few nucleotides change. – Ex: Oops! Original Mutation DNA: G A T C T C A G G C T A DNA: G A T C T A A G G C T A mRNA: C U A G A G U C C G A U mRNA: C U A G A U U C C G A U Protien: Leu-Glu-Ser-Asp Protien: Leu-Asp-Ser-Asp Kinds of Mutations • Chromosomal Mutations: change entire DNA – Frameshift mutations occur when the entire reading frame changes. – Ex: A nucleotide gets added (insertion). A Original Mutation DNA: G A T C T C A G G C T A DNA: G A T C T A C A G G C T A mRNA: C U A G A G U C C G A U mRNA: C U A G A U G U C C G A U Protien: Leu-Glu-Ser-Asp Protien: Leu-Asp-Val-Arg Kinds of Mutations • Chromosomal Mutations: change entire DNA – Frameshift mutations occur when the entire reading frame changes. – Ex: A nucleotide gets added (insertion). – Ex: A nucleotide gets taken away (deletion). Original Mutation DNA: G A T C T C A G G C T A DNA: G A T C T A G G C T A A mRNA: C U A G A G U C C G A U mRNA: C U A G A U C C G A U U Protien: Leu-Glu-Ser-Asp Protien: Leu-Glu-Ser-Iso Kinds of Mutations • Chromosomal Mutations: change entire DNA – Change in number of chromosomes. – Ex: Down Syndrome (47 chromosomes)