1. MUTATIONS
Stumpy Video

2. So what happened to Stumpy?

3. So then what happened?
What are possible causes of this?

4. Are all Stumpy’s cells affected?
Possible scenario #1: DNA was miscopied when his parents gametes were formed = all cells in the body have this mutation
Possible scenario #2: When he was developing, DNA was miscopied in the stem cells (unspecialized cells) that became legs = only those cells have the mutation
Answer = We don’t know! How could we find out?

5. Types of DNA mutations:
Single gene mutations
Only affects a single gene
Also called point mutations
Chromosomal mutations
Affects multiple genes at a time

6. Single Gene / Point Mutations:
Example 1 – What happens?
T C A G T C A T C A G C  T A G T C A T C A G C
Deletion – all bases shift left/back after mutation
Example 2 – What happens?
T C A G T C A T C A G C  T C C A G T C A T C A G C
Addition – all bases shift right/forward after the mutation
Example 3 – What happens?
T C A G T C A T C A G C  T A A G T C A T C A G C
Substitution – only one codon affected

7. Chromosomal Mutations:
Deletion
Addition
Inversion
Translocation

8. Other DNA / Chromosomal abnormalities?
Fertilized egg partially splits in utero or twins cells fuse in utero = conjoined twins
Extra or missing chromosomes can result in disorders –Downs syndrome, Turners syndrome, Klinefelter's syndrome…
***We can discuss these during our genetics unit***

9. What are some DNA mutations in humans?
Sickle Cell Anemia video
Caused by only one base pair substitution
Albinos
Cause by a mutation in one of a few genes that are know to produce melanin
Why is the albino trait more common in humans or pets than in wild animals