Mutations Changes to DNA

1. Mutations Changes to DNA

2. TACGCACATTTACGTACG DNA aa aa aa aa aa aa aa AUGCGUGUAAAUGCAUGC mRNA protein trait Mutations • Changes to DNA are called mutations • change the DNA • changes the mRNA • may change protein • may change trait

3. Types of mutations • Changes to the letters (A,C,T,G bases) in the DNA • point mutation • change to ONE letter (base) in the DNA • may cause change to protein, may not • frameshift mutation • addition of a new letter (base) in the DNA sequence • deletion of a letter (base) in the DNA • both of these shift the DNA so it changes how the codons are read • big changes to protein!

4. Point Mutations • One base change • can change the meaning of the whole protein THEFATCATANDTHEREDRATRAN Does this changethe sentence? A LITTLE! THEFATCARANDTHEREDRATRAN OR THEFATCATENDTHEREDRATRAN

5. Point Mutations • Missense mutation = changes amino acid AUGCGUGUAUACGCAUGCGAGUGA MetArgValTyrAlaCysGluStop Doesthis changethe protein? DEPENDS… AUGCGUGUAUACGUAUGCGAGUGA MetArgValTyrValCysGluStop

6. Sickle cell anemia • Hemoglobin protein in red blood cells • strikes 1 out of 400 African Americans • limits activity, painful & may die young Normalround cells Misshapensickle cells Only 1 out of146 amino acids

7. Point Mutations • Silent mutation = no change to protein AUGCGUGUAUACGCAUGCGAGUGA MetArgValTyrAlaCysGluStop Does this changethe protein? Why not? The code hasrepeats in it! AUGCGUGUAUACGCUUGCGAGUGA MetArgValTyrAlaCysGluStop

8. Point Mutations • Nonsense mutation = change to STOP AUGCGUGUAUACGCAUGCGAGUGA MetArgValTyrAlaCysGluStop Really destroyedthat protein! AUGCGUGUAUAAGCAUGCGAGUGA MetArgValStop

9. Frameshift Mutations • Add or delete one or more bases • changes the meaning of the whole protein THEFATCATANDTHEREDRATRAN Does this changethe sentence? A LOT! Delete one! Add one! THEFATCANTANDTHEREDRATRAN OR THEFATCAANDTHEREDRATRAN

10. Frameshift Mutations • Addition = add one or more bases AUGCGUGUAUACGCAUGCGAGUGA MetArgValTyrAlaCysGluStop Does this changethe protein? A LOT! AUGCGUGUAUACGUCAUGCGAGUGA MetArgValTyrValMetArgValA

11. Frameshift Mutations • Deletion = lose one or more bases AUGCGUGUAUACGCAUGCGAGUGA MetArgValTyrAlaCysGluStop Does this changethe protein? A LOT! AUGCGUGUAUACGAUGCGAGUGA MetArgValTyrAspAlaSerGA

12. Cystic fibrosis • Broken salt channel in cells • strikes 1 in 2500 white births • gene codes for a protein channelthat allows salt to flow across cell membrane • broken protein doesn’t work as channel • doesn’t allow salt out of cell, so water doesn’t flow out either • thicker & stickier mucus coating around cells • mucus build-ups in lungs & causes bacterial infections • destroys lung function • without treatment children die before 5; with treatment can live past their late 20s

13. Salt channel transports salt through protein channel out of cell Osmosis problems! Effect on Lungs normal lungs airway salt salt channel normal mucus H2O cells lining lungs cystic fibrosis salt  thick mucus H2O mucus & bacteria build up= lung infections & damage

14. Deletion leads to Cystic fibrosis deletion Loss of one amino acid!

15. Not to ask questionsis a mutation!