1. Mutations
A mutation is any change in the DNA sequence.

2. Mutations in Reproductive Cells
Only in gametes can mutations be passed on to offspring

3. Mutations in Body Cells
Somatic (normal/non-sex cells)
cannot be passed on to offspring

4. Types of Mutations
Gene mutations- changes to a specific gene. (DNA base pairs)
Chromosomal mutations- changes to a portion of the chromosome
Can affect many genes

5. Different Types of Gene Mutations
Point mutation-a change in a single base pair in the DNA.
THE DOG BIT THE CAT
THE DOG BIT THE CAR
THE DOG BAT THE CAR
THE DIG BAT THE CAR

8. Point Mutation

9. Frameshift Mutation
a single base pair is added or deleted, causing a shift in how the strand will be read.
THE DOG BIT THE CAT
THE DO BIT THE CAT
THE DOB ITT HEC AT

10. Chromosome Mutations
Deletion-part of a chromosome is left out.

11. There is a small section of chromosome #5 that has been deleted

12. Insertion-part of a chromatid breaks off & attaches to its sister chromatid.

13. Inversion-part of a chromosome breaks off & reinserts backwards.

14. Translocation-part of one chromosome breaks off & is added to a different chromosome.

15. Nondisjunction- have an abnormal number of chromosomes
Caused by errors in Mitosis or Meiosis
Most die before birth
Results in either monosomy or trisomy

17. Down’s Syndrome Traits
Down’s Syndrome is an example of nondisjunction
Results from trisomy of the 21st pair of chromsomes (3 chromosomes)
Mental retardation, short stature, heart defects, most are sterile, and other problems

18. There is an extra chromosome on the 21st pair
Down’s Syndrome
There is an extra chromosome on the 21st pair

19. Turner’s Syndrome Traits
Turner’s Syndrome occurs only in females
Results from monosomy X
People with syndrome are sterile
Secondary sex characteristics don’t develop

20. What causes mutations? spontaneous mistakes environment
any agent that can cause a change in DNA is called a mutagen. (x-rays, UV light, asbestos)

21. DNA Repair
enzymes in our cells remove the incorrect nucleotides & replace them with the right ones.
this works well, but is not perfect