DNA (Gene) Mutations

1. DNA (Gene) Mutations

2. Parts of DNA will have a base (or more) missing, added, or incorrect A mistake in the genetic code Wrong instructions  wrong building materials  wrong structure. What is a gene mutation?

3. Mutations occurs at a frequency of about 1 in every 1 billion base pairs Everybody has about 6 mutations in each cell in their body! How common are mutations?

4. Mutations are not always seen. Every part of your DNA doesn’t make a protein or trait. Remember introns and exons? Some genes are recessive and are therefore hidden, they can be passed to your kids but you don’t notice them. If I have that many mutations, why don’t I lookweird?

5. Substitution Point mutations Frame shift mutations (2 kinds) Insertion Deletion The most common types of gene mutations are:

6. Normal DNA: CGA – TGC – ATC Mutated DNA: CGA – TGC - TTC DNA (Gene) Mutation What happened?

7. Normal DNA: CGA – TGC – ATC Mutated DNA: CGA – TGC - TTC DNA (Gene) Mutation #1 *Adenine was accidentally replaced with thymine *What is this mutation called?

8. Normal DNA: CGA – TGC – ATC Amino acids: Ala -- Thr -- stop Mutated DNA: CGA – TGC – TTC Amino acids: Ala -- Thr -- Lys Substitution (point mutation) What will happen to the amino acids? How many will be affected?

9. Normal DNA: CGA – TGC – ATC Mutated DNA: CGA – TAG – CAT - C DNA (Gene) Mutation #2 What happened?

10. Normal DNA: CGA – TGC – ATC Mutated DNA: CGA – TAG – CAT - C DNA (Gene) Mutations *Adenine was inserted,causing the remaining DNA to shift to the right *What is this mutation called?

11. Normal DNA: CGA – TGC – ATC Amino acids: Ala -- Thr -- stop Mutated DNA: CGA – TAG – CAT – C Amino acids: Ala -- Tyr -- Val -- ….. Insertion What will happen to the amino acids? How many will be affected?

12. DNA (Gene) Mutation #3 Normal DNA: CGA – TGC – ATC Mutated DNA: CGA – TCA- TC What happened?

13. DNA (Gene) Mutation Normal DNA: CGA – TGC – ATC Mutated DNA: CGA – TCA- TC *Guanine was removed,causing the remaining DNA to shift to the left *What is this mutation called?

14. Deletion Normal DNA: CGA – TGC – ATC Amino acids: Ala -- Thr -- Stop Mutated DNA: CGA – TCA- TC Amino acids: Ala -- Ser --……. What will happen to the amino acids? How many will be affected?

15. • What causes mutations? Replication errors Transcription errors Cell division errors Spontaneous changes Mutagens • Mutagen? What’s that? • “Stuff” that causes mutations when a cell is exposed. • Examples: UV light, Xrays, chemicals, etc.

16. What happens to someone with a mutation? • That all depends….. • What kind of mutation it is. • How many proteins are affected. • Where in the polypeptide chain is the mutation. • How many cells does it affect. • Mutations can be fatal, harmful, beneficial or nuetral.

17. •Which mutation would have the least effect on an organism? • On intron sections of DNA • On unexpressed recessive traits. • Point mutations/substitutions • Only affects 1 amino acid.

19. •Which mutation would have the most effect on an organism? • Frame-shift mutations: • Deletions and insertions affect all amino acids after the mutation.

20. • When would a mutation have the most effect on an organism? • During Meiosis • If gametes are produced with mutations, those mutations will be passed onto the offspring……. • Every cell of organism will contain mutation.

21. Enzymes proofread the DNA and replace incorrect nucleotides with correct nucleotides. The greater the exposure to a mutagen such as UV light, the greater the chance that a mistake will not be corrected. Repairing DNA

22. Chromosomal mutations • Mutations that involve changes in number or structure of chromosomes.

23. When part of a chromatid breaks off and attaches to its sister chromatid, an insertion occurs. Duplicationis when an extra copy of a gene is made. Insertion/duplication A B C D E- F G H A B C B C D E- F G H

24. Deletion • When a part of a chromosome is left out, a deletion occurs A B C E- F G H A B C D E - F G H deletion

25. When part of a chromosome breaks off and reattaches backwards, an inversion occurs. Inversion A B C D E- F G H A D C B E- F G H Inversion

26. Translocation • When part of one chromosome breaks off and is added to a non-homologous chromosome, a translocation occurs A B C D E- F G H W X A B C D E- F G H W X Y - Z Y - Z Translocation

27. Nondisjunction • Failure of chromosomes to separate properly. This results in too many chromosomes or too few.

28. Trisomy 21: three copies of chromosome number 21  “Down syndrome. • Turner’s syndrome: Female with only one copy of the X chromosome. • Klinefelter’s syndrome: Male with an extra X chromosome.