Bacterial Genetics

1. Bacterial Genetics • Dr. RashadShawgiBabiker • M.Sc. (Microbiology) (UMST) • M.Sc. Stud. (Immunology ) • Institute of Tropical Medicine.(SAS)

2. MicrobialGenetics • Basic Molecular GeneticsCentral Dogma Gene Expression • Genetic VariabilityMutations Recombination Plasmids • Genetic EngineeringTerminology and Technology Products and Benefits

3. Introduction DNA is arranged as a single molecule with no histones present, and with no dominance or recessiveness in the genes. Bacterial chromosome is located in the nucleoid. In E. coli there are 4000 genes spread over 1.5mm of DNA in less than 1 micrometer of space

4. Loop domain structure allows for compaction of DNA

6. DNA Structure

8. Transcription & Translation

9. Transfer RNA

10. F. Control of protein synthesis

12. MicrobialGenetics • Basic Molecular Genetics Central Dogma Genotype and Phenotype • Genetic Variability -Mutations -Recombinations:Transformation, Conjugation, Transduction -Plasmids: Conjugative, Resistance, Toxigenic, Metabolic • Genetic Engineering Terminology and Technology Products & Benefits of Genetic Engineering

13. Mutations Types of mutations Spontaneous Induced

14. Spontaneous mutations 1 mutation in every billion bacteria Example: Neisseria gonorrhoeae penicillin resistance original mutation was spontaneous

15. Induced mutations • Chemical or Physical agents enhance mutation rate • Mutagens • Ultraviolet light—mechanism of action • Chemicals

18. Mutation Type Point (substitution) (leu) (ser) (arg) Normal AAT AGT GCC (leu) (cyst) (arg) Mutant AAT TGT GCC

19. Mutation Type Frameshift (deletion) (leu) (ser) (arg) Normal AAT AGT GCC (leu) (val)(pro) Mutant AAT AGTGCCA

20. Mutation Type Frameshift (insertion) (leu) (ser) (arg) Normal AAT AGT GCC (leu) (glut)(cyst) Mutant AAT CAGTGCC

21. Repair Mechanisms DNA repair enzymes Many enzymes Constantly checking for errors Repair mechanisms Mismatch repair “proofreads” Damage repair Excision repair Dimer repair (UV light)

22. Mismatch Repair

23. Excision Repair

24. Transformation

26. Conjugation • Male and female cells • Role of F factors (plasmids) • High frequency of recombination strains • Mechanism of Hfr conjugation • Sexduction

27. Simple Conjugation

28. Hfr Conjugation

29. Transduction • Role of the bacteriophage • The lytic cycle • Lysogeny • Generalized transduction

30. Lysogeny

31. Plasmids • Fragments of DNA in the cytoplasm • R Factors - confer drug resistance • Bacteriocins -proteins toxic to other bacteria and human cell • Many plasmids are found in Gram-Negative bacteria

32. MicrobialGenetics • Basic Molecular Genetics Central Dogma Gene Expression • Genetic Variability Mutations, Recombinations, Plasmids • Genetic Engineering -Terminology: Genetic engineering, Gene cloning, Recombinant DNA technology, Restriction endonucleases, Vectors -Products of Genetic Engineering: Proteins, Genetically modified organisms, Genes therapy -Process of Genetic Engineering: Gene cloning, Gene characterization, Gene expression

33. Transposable genetic elements • Insertion sequences • Small DNA segments • Provide no genetic information • Located at several places on the chromosome • Transposons • Larger than Insertion sequences • Provide information for protein synthesis

34. Sections A & B repeating but reversed “palindrome”

36. Genetic Engineering Technology

37. The ‘Benefits’ of Genetic Engineering • Genetically engineered proteins: Hormones (e.g.interferons, erythropoietin, insulin, growth factors), Vaccines (e.g.Hep B), others • Genetically modified organisms: Genetically modified foods, herbicide and pesticideresistant plants • Genetically engineered genes: Genes for therapy