1. Mutations

2. We all make mistakes. Sometimes cells make mistakes, too -- -like when they copy their DNA.

3. Mutations Mutations are mistakes in DNA sequencing, and they affect the genetic information that is passed to offspring. Sometimes the mistakes are so small that they are never noticed, but sometimes they can cause a lot of problems.

4. Gene Mutations One type of mutation is a gene mutation. It changes just one gene.

5. Gene mutations may happen when: 1. one nucleotide is substituted for another nucleotide 2. a nucleotide is added to or taken away from a gene These changes can cause a protein to be changed so much that it can’t function properly.

6. Substitution: Normal: THE RAT HID AND THE CAT SAT AND GOT FAT. THE PAT HID AND THE CAT SAT AND GOT FAT.

7. Insertion/Frameshift: Normal: THE RAT HID AND THE CAT SAT AND GOT FAT. THE RAT HIX DAN DTH ECA TSA TAN DGO TFA T

8. Deletion/Frameshift: Normal: THE RAT HID AND THE CAT SAT AND GOT FAT. THE RAH IDA NDT HEC ATS ATA NDG OTF AT

9. Remember amino acids make up polypeptide chains, polypeptide chains make up proteins, and proteins are a vital component of living material and carry out vital cellular processes.

10. Remember The mRNA sequence (Which is a copy of DNA) determines the amino acid that is added to the polypeptide chain. If one or more amino acids added to that polypeptide chain are wrong, the organism will not be able to build proteins with the correct structure.

11. Mutagens Mutagens are external agents that can cause gene mutations, ex. Radiation and chemicals.

12. Carcinogens A common result of gene mutation is cancer. Mutagens that are linked to cancer are called carcinogens, ex. UV rays, Radiation from x-rays, tobacco, asbestos, and benzene.

13. The other type of mutation is a chromosomal mutation, where 1. the structure of the chromosomes changes.

14. This usually occurs between Metaphase and Anaphase of Mitosis

15. Parts of chromosomes can be broken off or lost during the processes of mitosis or meiosis.

16. Duplication and Deletion These broken parts can sometimes reattach to a sister chromatid and cause duplication of genetic information in one chromtaid and deletion of genetic information in the other.

17. Inversion If the broken parts reattach backwards, it is called an inversion

18. Translocation The broken parts may also attach to another chromosome and is called translocation.

19. Chromosomal Mutation 2. Non-disjunction- the Chromosome Number Changes In humans the Normal Chromosome Number is 46.

20. Chromosomal mutations can pass on defective chromosomes, or they can cause too many or too few chromosomes to be passed on. If the mutation occurs during meiosis, the defective chromosomes may be passed onto the offspring.

21. Example: Down’s Syndrome People with Down’s Syndrome have three copies of chromosome 21instead of two. They usually have mild to severe mental retardation and are more likely to have heart problems and other health problems.