Mutations

1. Mutations Chapter 12Section 4

2. Mutations Mutations are changes in the DNAsequence. This change may affect: a single gene or an entire chromosome

3. Gene Mutations Changes in a single gene Takes place during DNA replication Can involve one or morenucleotides (bases)

4. Types of Gene Mutations Point mutations A change in one nitrogen base in a DNA sequence Examples: 1.Substitution 2.Insertion 3.Deletion

5. Types of Gene Mutations Substitution One base is replaced by a different one Can result in a change in one amino acid of a protein • Normal DNA: TGA TCT ACT • mRNA: ACU AGA UGA amino acid: (arginine) Substitution= DNA: TGA TCC ACT • mRNA: ACU AGG UGA amino acid: (arginine)orSubstitution= DNA: TGA TTT ACT • mRNA: ACU AAA UGA amino acid: (lysine)

6. Types of Gene Mutations Substitution One base is replaced by a different one Can result in a change in one amino acid of a protein

7. Types of Gene Mutations Point mutations…..Substitution Sickle Cell Anemia Normal- DNA: TAG CTT ATT mRNA: AUC GAA UAA Sickle Cell- DNA: TAG CAT ATT mRNA: AUC GUA UAA Change in one amino acid Glutamic acid is replaced by Valine

8. Types of Gene Mutations Insertion One base is addedto the DNA segment Causes a frameshift Insertion

9. Types of Gene Mutations Deletion One base is omittedfrom DNA segment Causes a frameshift Deletion

10. Types of Gene Mutations Example of deletion mutations: Tay Sachs disease: A genetic abnormality caused by large amounts oflipids built up on neurons in the brain Leads to paralysis Cystic Fibrosis: Deletion- Three nucleotides or one codon omitted. Normal- DNA: TAG TAA AAA CCT CAC mRNA: AUC AUU UUU GGA GUGCystic DNA: TAG TAA CCT CAC Fibrosis- mRNA:AUC AUU GGA GUG

11. The Cause of Cystic Fibrosis CFTR gene The most common allele that causes cystic fibrosis is missing 3 DNA bases. As a result, the amino acid phenylalanine is missing from the CFTR protein. Normal CFTR is a chloride ion channel in cell membranes. Abnormal CFTR cannot be transported to the cell membrane. The cells in the person’s airways are unable to transport chloride ions. As a result, the airways become clogged with a thick mucus.

12. Types of Gene Mutations Frame shift mutations: Caused by the insertion or deletion of a nitrogen base in the DNA sequence Shifts the “reading frame” of the genetic message Affects every amino acid that follows the point of insertion or deletion Can alter a protein so that it cannot perform its normal function

13. Review of Gene Mutations Check out this video clip!

14. Chromosomal Mutations Results in changes in wholechromosomes Can cause changes in the numberof chromosomes • Can be neutral, have a minor affect or be lethal • Examples: • Trisomy 21 (Down Syndrome) • Klinefelter Syndrome • Trisomy 13 • Turner’s Syndrome

15. Chromosomal Mutations Can cause changes withinthe chromosomes • Locationof genes • Numberof genes • These lettersrepresent genes

16. Chromosomal Mutations • Types of Chromosomal Mutations: • A deletion involves the loss of all or part of a chromosome • A duplication occurs when a segment of a chromosome is repeated • An inversion happens when part of a chromosome becomes reversed • A translocation occurs when part of one chromosome breaks off and attaches to another, non-homologous chromosome

17. Deletion Duplication Inversion Translocation

18. Consequence of Mutations • Most mutations are minor • Many are harmful • Some are lethal • A few may be helpful

19. Mutation Examples Missing parts:

20. Mutation Examples • The rare black jaguar! (A gene mutation overproduces melanin in the fur.) Color Variation:

21. Mutation Examples Belgian Blue bull showing double muscling – no steriods, its a gene mutation for muscle growth that caused this to happen. Muscle bound: A baby Superman, born in Berlin with bulging arm and leg muscles. Not yet 5, he has muscles twice the size of other kids his age and half their body fat. DNA testing showed why: The boy has a genetic mutation that boosts muscle growth.

22. Mutation Examples • Phenotypic expression of aniridia with PAX6 gene mutation.

23. Mutation Examples Extra parts:

24. Mutation Examples Extra parts:

25. Mutation Examples Extra parts:

26. Mutation Examples • Extra parts:

27. Mutation Examples • Extra parts: Polydactyl

28. Mutation Examples • Extra parts:

29. Mutation Examples • An example of webbed toes sometimes seen in Andersen's Syndrome, caused by a gene mutation. Joined Parts:

30. Hensel Twins Abigail and Brittany

31. Mutation Examples • Just plain odd: pig dog

32. Mutation Trickery • This is not a gene mutation. This poor turtle spent a great deal of its life wrapped up in a milk ring or some other, probably plastic, man made piece of trash. • Looks like but isn’t a mutation:

33. Mutation Trickery or Genetic Engineering? Science Ethics: British scientists will be allowed to research devastating diseases such as Alzheimer's and Parkinson's using human-animal embryos, after the House of Commons rejected a ban yesterday. • Gene therapy has taken a new turn as "hybrid" gene "mutations" are purposefully being sought out in science labs across the world. • Breeding the Mutant Gene

34. Humans could mutate into their most basic forms.