Mutation, DNA Repair and Recombination.pptx

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1. Mutation, DNA Repair and Recombination A GENETIC REPORT FROM CHRISTIAN MOISES O DE GUZMAN BSED 2 D – Science

2. Mutation A change in genetic information in a cell

3. TYPES OF MUTATION Large scale Mutation - a whole chunk of a chromosome is either lost, relocated or rearranged

4. TYPES OF MUTATION 2. Point Mutation - change in only one base pair. A nucleotide-pair substitution occurs.

5. TYPES OF MUTATION Nucleotide-pair substitution One base pair is replaced with a different base pair If this is not within a gene there should be no effect If this happen within a gene, there are several possible results

6. TYPES OF MUTATION Several Results: Silent mutation – new mRNA codon that translates for the same amino acid

7. TYPES OF MUTATION Missense Mutation new mRNA codon translate new different amino acid (most common & effects will vary

8. TYPES OF MUTATION Nonsense Mutation – new mRNA (stop codon) no longer code for amino acid

9. TYPES OF MUTATION Frameshift Mutation Insertion/Deletion – where one base pair suddenly deleted or added in a sequence. The sequence will be altered resulting missense mutation and premature stop codon

10. CAUSES OF MUTATION SPONTANEOUS MUTATION – cellular machinery makes a mistake by itself. Happens during replication Thanks to repair enzymes (DNA mismatch repair) 1/10 Billion base pairs

11. CAUSES OF MUTATION 2. Pyrimidine Dimers (Mutagens) – agents for mutation such as radiation Ex. UV light distorts(lesion) genetic activity as it collides to DNA

12. CAUSES OF MUTATION 3. Chemical Mutagens a. oxidizing agents – a substance that tends to bring about oxidation by being reduced and gaining electrons

13. CAUSES OF MUTATION b. alkylating agents – add things like methyl groups to existing bases, interferes with replication and transcription

14. Genetic Disorders Alzheimer’s Disease is a brain disorder that slowly destroys memory and thinking skills and, eventually, the ability to carry out the simplest tasks.

15. Genetic Disorders Cystic Fibrosis  is an inherited disorder that causes severe damage to the lungs, digestive system and other organs in the body.

16. Genetic Disorders Down Syndrome  is a condition in which a child is born with an extra copy of their 21st chromosome — hence its other name, trisomy 21. This causes physical and mental developmental delays and disabilities.

17. DNA Repair

18. DNA Repair Collection of processes by which cell Identifies and corrects damage to the DNA molecules

19. How DNA can be damaged? Endogenous – internal sources (cell metabolism) Exogenous – external sources (environmental factors)

20. Single Strand Repair Mechanism Nucleotide Excision Repair When exposed to UV lights, pyrimidine bases are damaged. Endonucleases is an enzyme for recognition and cutting (excision) of damaged nucleotides. Polymerase replaces the bases and ligase reseals the gap

21. 2. Base Excision Repair There is a damaged in a particular DNA base It caused by certain chemicals resulting to Deamination Glycosylases are used to recognize and remove damaged space. Endonuclease cuts the phosphodiester backbone that is left behind. Then, polymerase and ligase taken into action Single Strand Repair Mechanism

22. 1 2 3 4

23. 3. Mismatch Repair Repair errors during DNA replication and recombination Methylation distinguish newly-synthesized daughter strand with the error from the correct parental strand (Prokaryotes) Single Strand Repair Mechanism

24. Damage occurs to both stands in the double helix Caused by ionizing radiation (gamma and X rays) - Pathways that repairs double helix strand breaks in DNA Double Strand Repair

25. Double Strand Repair Homologous End Joining (HEJ) Requires nearly-identical sequence as a template for the repair of the break Use sister chromatids or homologous chromosome

26. 2. Non-homologous end joining (NHEJ) Does not need homologous template Directly connects the end-to-end of the DNA sequence Double Strand Repair

27. 3. Microhomology Mediated End Joining (Alternative NHEJ) Use Micro homologous sequences during alignment of broken ends Double Strand Repair

28. DNA Recombination Change of genetic information

29. DNA Recombination Change of genetic information (order, pattern, content) Can be done in number of ways

30. General recombination - exchange of genes between two DNA or chromosome molecules. DNA Recombination

31. 2. Insite-specific recombination - exchanges only happen at a certain sequence of DNA DNA Recombination

32. 3. DNA transposition - involves short piece of DNA that can move from one place in a chromosome to another DNA Recombination

33. Mutation, DNA Repair and Recombination “THE END”