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Chapter 13.3 (Pgs. 372-376):Mutations
Mutations- Are heritable changes in genetic
information
- Have two major types:- Chromosomal mutations- Point mutations
- Can be harmful or beneficial
Chromosomal Mutations- Involve changes in the number or structure of
chromosomes
- Deletion- Loss of all or part of a chromosome
- Duplication- Produces an extra copy of all or part of a
chromosome
- Inversion- Reverses the direction of parts of a chromosome
- Translocation- Part of one chromosome breaks off and attaches
to another chromosome
Point Mutations
- Are mutations that involve changes in one or more nucleotides
- Occur at a single point in the DNA sequence
- Can cause changes to occur further along the DNA molecule from the initial mutation
Point Mutations- Substitution
- One nucleotide is changed to a different nucleotide
Sickle Cell Anemia
Point Mutations- Insertion or Deletion
- One nucleotide is inserted or removed from the DNA sequence
Huntington’s Disease
Muscular Dystrophy
Point Mutations- Frameshift
- Mutations that change the “reading frame” of DNA
- Change the sequence of DNA from the initial point of mutation
Causes of Mutations
- Include naturally-occuring errors - Can occur during replication
- Include chemical and physical agents in the environment, called mutagens- Chemicals- Radiation
Effects of Mutations- Can be harmful
- Change protein structure or gene activity in a negative way
- Sickle cell anemia
- Can be helpful- Change protein structure or gene
activity in a positive way- Increase disease resistance- Create better physiological function
- Some mutations have no effect at all