Mutations or How a perfectly good system can go wrong go wrong go wrong

1. MutationsorHow a perfectly good system can go wrong go wrong go wrong

2. There are 2 types of mutations 1)Chromosomal rearrangements. • There are too many or too few chromosomes. (nondisjunction and polyploidy) • Part of the chromosome is flipped on the same chromosome, or taken away or rearranged on a different chromosome (Inversion, deletion, translocation) 2)Gene Mutations. (occur on the DNA) __One of the base pairs is substituted with another (point mutation) __ A new base pair is Added (frame shift insertion) __ One of the base pairs is deleted (frame shift deletion)

3. Mutations • Mutations are the original source of all variations. • Each mutation changes the allele frequency of a gene in a population. • WE are all born with at least 3 mutations. • Mutations in somatic cells are passed on to daughter cells in that organism . (E.g. 1 skin cell to another.) • Mutations in sex cells are passed on to the gametes  then zygotes. In other words all offspring. • (That’s why the dentist puts a lead apron on your lap when you have an X-Ray.)

4. Plants VS Animals • Plants can breed both sexually and asexually • Any mutation can be passed on to offspring. • Animals mostly reproduce sexually • In animals mutations can only be passed on to children if they happen in your gametes. • If the mutation is large the zygote dies. • If it is a small mutation the zygote survives.

5. Are mutations bad?Why do they persist in populations? • Whether or not a mutation is harmful or beneficial can depend on the environment. • Sickle-Cell anemia is very prevalent in equatorial Africa. So is Malaria. Both kill. • Let N= normal RBC Let n= sickled RBC NN Nnnn Is protected from SCA Is protected form Is killed by SCA Is killed by Malaria both Is protected from Malaria

6. Some mutations occur spontaneously Dwarfism: Half of all dwarfism genes are newly mutated. Hemophilia: A sex linked trait. Your blood does not clot. So you can easily bleed to death from a bump. This gene is detrimental to health. Why doesn`t it just die out? Mutations just keep happening. 3 out of every 100,000 gametes

7. Nondisjunctionin one pair of chromosomes • Sometime in meiosis 1 one set of chromosomes will stick together and one egg will get egg will get 2 and the other will get none. • If this egg is fertilized the egg will either have 3 chromosomes (trisomy) • Or 1 chromosome (monosomy)

8. Down`s syndromeTrisomy 21

9. Polyploidyoccurs in all chromosomes • Normally we have 2 sets of each chromosome. This is called diploid. • If meiosis stops half way through you can get a diploid gamete. + = + = diploid gamete.

10. When Polyploidy occurs in Plants it makes a stronger healthier, more rigorous plant. • Most of the fruit, and grains you eat are polyploidy. The strawberries we pulled DNA from were octoploidy, 8 sets of chromosomes. • When polyploidy occurs in animals it is almost always lethal

11. Gene MutationsPoint mutation is a substitution of 1 base for another. IF it mutation is in the third base of the triplicate code, It doesn`t make much difference. You can spell the amino acid many ways.

12. If you change the 2nd letter in the triplicate code sometimes it makes a difference and sometimes not.

13. If you change the first letter of the triplicate code there are always major effects.

14. Frame shift mutationsThese are very detrimental and the organism rarely survives. • Deletions • Jan can see her new hat Let`s delete the n.Everything else must move over. • Jan caseehernewh at_ the entire gene is changed and makes no sense. • Insertions • Jan can n see her new hat let`s insert another n and see what happens? • Jan can nseehernewha t_ _ still no good major change