presentation
- 1. Mutations Ph student :Amel Mahrooz Abdullah ÇANKIRI KARATEKİN ÜNİVERSİTESİ FEN BİLİMLERİ ENSTİTÜSÜ
- 2. Mutation Is a process that produces a gene or chromosome that differs from the wild type. The mutation may result due to changes either on the gene or the chromosome itself.
- 3. History The earliest record of point mutation dates back to 1791, when Seth Wright noticed a lamb with exceptionally short legs in his flock of sheep. The first scientific study of mutation started in 1910, when Morgan started his work on fruit fly Drosophila melanogaster after he observed white eyed male individuals among red eyed male individuals.
- 4. Mutations can be bad, leading to cancer, aging, birth defects, self aborted embryos Be good, making an organism survive better in its environment Example: bacteria becoming antibiotic resistant
- 5. Mutagens The substances or agents which induce mutations. They may be physical, chemical or biological. 1.Physical i.Ionizing : Radiations- Xrays, gamma, Alpha,Beeta, protons, nutrons etc .. ii. Non Ionizig : Temperature 2.Chemical : Elements such as arsenic, nickel and chromium. Some organic compounds like benzene are also considered to be mutagenic in nature.
- 6. 3.Biological Mutagens: They may be viral or bacterial. H. Pylori- implicated in stomach cancer Hepatitis B virus- implicated in liver cancer H. papiloma virus-implicated in cervical cancer Human T-cell lymphocytic virus implicated in lymphoma
- 7. Types of Mutation Mutations can be grouped according to Their size The Type of Cell Involved Mode of Origin Direction of Mutation Phenotypic Effects
- 8. Mutations by their size Submicroscopic (micro mutations, gene mutations a single base. Microscopic macro mutations , chromosomal abnormalities.
- 9. Gene Mutations Change in the nucleotide sequence of a gene may only involve a single nucleotide Types of Gene Mutations Point Mutations a) Missense b) Nonsense c) Silent Frameshift a) Insertions b) Deletions
- 10. Point Mutations Point Mutations or substitution is a genetic mutation where a single nucleotide base is changed
- 11. a. Missense Mutation This type of mutation is a change in one DNA base pair that results in the substitution of one amino acid for another in the protein made by a gene. Example is Sickle cell anemia
- 12. b. Nonsense Mutation Is also a change in one DNA base pair. Instead of substituting one amino acid for another, however, the altered DNA sequence prematurely signals the cell to stop building a protein. This type of mutation results in a shortened protein that may function improperly or not at all. Examples include duchenne muscular dystrophyand thalassemia
- 13. c. Silent Mutations Are mutations in DNA that do not have an observable effect on the organism's phenotype. For example ,if the codon AAA is altered to become AAG, the same amino acid –lysine–will be in corporated into the peptide chain
- 14. Frame Shift Mutations 1. Insertion Mutations : An insertion changes the number of DNA bases in a gene by adding a piece of DNA. As a result, the protein made by the gene may not function properly. Examples Cystic fibrosis. Example UUU UUA UCU Phe-Leu-Ser UUU UUA UUU UCU Phe-Leu-Phe-Ser
- 15. 2. Deletion A deletion changes the number of DNA bases by removing a piece of DNA. Small deletions may remove one or a few base pairs within a gene, while larger deletions can remove an entire gene or several neighboring genes. Example UUU UUA UUU UCUPhe-Leu-Phe-Ser UUU UUA UCUPhe-Leu-Ser
- 16. Chromosomal mutation Types of chromosomal abnormalities Numerical abnormalities : polyploidy : triploidy , tetraploidy aneuploidy : trisomy , monosomy Structural abnormalities 1 .Balanced : if there is no gain or loss of chromosomal material • Translocations • Inversions 2. Unbalanced if there is gain or loss of chromosomal material • Duplication • Deletion • Insertion • Ring chromosome Polyploidy:occurs when there are more than two paired (homologous) sets of chromosomes(triploidy, tetraploidy, etc.).
- 17. Balanced Structural chromosomal abnormalities Translocations Movement of a gene may take place to a non-homologous chromosome and this is known as translocation
- 18. Inversion The movement of a gene within the same chromosome is called inversion.
- 19. Unbalanced Structural chromosomal abnormalities Duplication occurs when a segment of the chromosome is repeated, once or several times. Deletion -loss of a segment of the chromosome
- 20. Unbalanced Structural chromosomal abnormalities Ring chromosome Two ends of the segment between break points are joined to form a circular structure.
- 21. Mutations can be grouped according to Their size The Type of Cell Involved Mode of Origin Direction of Mutation Phenotypic Effects
- 22. 1. Somatic mutations Mutations that are in the somatic tissues of the body. Mutations are not transmitted to progeny caused by environmental factors, such as exposure to ultraviolet radiation 2. Germinal mutations Mutations that are in the germ tissues of the body. Mutations may be transmitted to progeny can be caused by radiation or chemical mutagens
- 23. Mutations can be grouped according to Their size The Type of Cell Involved Mode of Origin Direction of Mutation Phenotypic Effects
- 24. 1. Spontaneous mutations The spontaneous mutations occur suddenly in the nature and their origin is unknown. They are also called “background mutation” and have been reported in many organisms such as, Oenothera, maize, bread molds, microorganisms (bacteria and viruses), Drosophila, mice, man, etc. 2. Induced mutations Besides naturally occurring spontaneous mutations, the mutations can be induced artificially in the living organisms by exposing them to abnormal environment such as radiation, certain physical conditions (i.e., temperature) and chemicals.
- 25. Mutations can be grouped according to Their size The Type of Cell Involved Mode of Origin Direction of Mutation Phenotypic Effects
- 26. 1. Forward mutations In an organism when mutations create a change from wild type to abnormal phenotype, then that type of mutations are known as forward mutations..A forward mutation takes place in the in E. coli, inactivates the gene and makes it unable to grow in a medium containing lactose 2. Reverse or back mutations The forward mutations are often corrected by error correcting mechanism, so that an abnormal phenotype changes into wild type phenotype.
- 27. Mutations can be grouped according to Their size The Type of Cell Involved Mode of Origin Direction of Mutation Phenotypic Effects
- 28. 1. Morphological mutations Mutations that affect the visible form properties of an organism change in size, shape (normal wing vs. curly wing in fruit flies) 2. Lethal mutations Are mutations that affect the viability of the organism (i.e. Manx cat). 3. Conditional mutations Are mutations in which the mutant allele causes the mutant phenotype only in certain environments (called the restrictive condition).
- 29. 4. Biochemical mutations Are mutations that may not be visible or affect a specific morphological characteristic but may have a general affect on the ability to grow or proliferate.
- 30. Thank you