Upload
jessie-holt
View
217
Download
4
Embed Size (px)
Citation preview
Mutations
• Change / alteration to the DNA of an organism• They may be good, bad or have no effect• A plant that can better tolerate the cold (GOOD)• A change that causes some syndrome or illness (BAD)• A change that we never see or notice (NONE)
• A driving force behind evolution• A plant that can better tolerate the cold (GOOD)
Causes of mutations
• Naturally occurring (they just happen) 2/3 of all cancers
• Mutagen – something in the environment that causes a change
• Examples: radiation (x-rays), pollution and toxic chemicals (Love Canal), smoking, diet, etc….
Types of mutations
• Genetic – causes a change in the gene• May only effect one gene• Change in the base (A,T, C, G)
• Chromosomal – causes a change in a chromosome or segments of a chromosome
Genetic mutations
• 1.Deletions: remove a base from the sequence • ATCCGACAG (codons are in groups of 3)• ATCGACAG
• 2.Insertions: a base is added to the sequence• ATCCGACAG• ATTCCGACAG
• These are both called frameshift mutations they cause a change in how the sequence is read
Types of genetic mutations
• 3. Substitutions: a base is changed (one is substituted for another)
• AGGCAA• AGCCAA• A substitution may not cause any change in
the amino acid
Examples of genetic mutations
• Color blindness – x chromosome (sex linked)• Hemophilia – x chromosome (sex linked)
(free bleeding)• Sickle cell – chromosome 11 (causes a change
in the shape of red blood cells)
Chromosomal mutations
• Deletions – chromosome is deleted• Duplication – chromosome is duplicated• Inversion – chromosome is inverted• Translocation – piece of a chromosome is
moved to another chromosome (not homologous)
• Non-disjunction – chromosomes don’t separate properly
Examples of chromosomal mutations
• Downs syndrome – trisomy 21 (3 copies of the 21 chromosome total of 47 chromosomes)
• Turner’s syndrome – x or piece of the x chromosome is missing (45 chromosomes)
• Klinefelter’s syndrome – xxy (47 chromosomes an extra x chromosome)