1. Genetic Changes 11.3

2. Genetic Changes DNA controls cell structure and function
What happens if nucleotide sequence is changed?

3. Genetic Changes Sometimes no harm is done, tailless manx cat
Some changes cause cell to behave differently, UV rays cause cancerous cell division

4. Mutation Any change in DNA sequence
A mutagen is something that can cause a change in DNA
Can we name some mutagens?

5. Mutation Mutagens include
Radiation => x-rays, ultraviolet light, nuclear radiation
Chemicals => dioxins, asbestos, benzene, formaldehyde

6. Mutation Mutations in reproductive cells
Change in DNA in sperm or egg cell
Could lead to new trait
Could lead to a protein that does not work correctly, the zygote may not survive

7. Mutation Mutations in body cells
Mutation not passed on to offspring, but could cause problems for the individual
Skin cell may lose elasticity, when the cell divides, daughter cells also lack elasticity
If mutation affects cell division, can cause cancer

8. Types of Mutation Point mutation – change in a single base pair in DNA
The dog bit the cat.
The dog bit the car.

9. Types of Mutation
Frameshift mutation – a single base is added or deleted from DNA
Changes all the codons after the mutation

10. Types of Mutation
Chromosomal mutations – common in plants,parts of chromosomes break off, join incorrectly, crossover with the wrong chromosome
Lead to nondisjunction because homologous chromosomes cannot pair when some have extra parts
Few chromosome mutations are passed on to offspring because zygote usually does not survive, or is unable to reproduce

11. Types of Mutation Chromosomal mutations Deletions Insertions
Inversions
Translocations

12. Repairing DNA
Enzymes proofread the DNA and replace incorrect nucleotides
Exposure to mutagens leads to more uncorrected mistakes