Microbial Genetics To know the genetic properties of

Microbial Genetics To know the genetic properties of microorganisms; In the investigation of gene functions, Reproduction of some special genes in other organisms in microorganisms, Production of some industrially important products in large quantities, In the treatment of microbial diseases and It is extremely important in determining how genes are transferred between organisms. Genetically modified microorganisms are used in these studies.

MUTATION All kinds of base number and sequence changes that occur in the DNA structure of an organism and are hereditary are called mutations. A mutant is defined as a live mutant that carries a different DNA from the ancestor type (wild type) and the causative agent is defined as mutagen.

Mutant types Oxotrophic mutants: They cannot develop on minimal media. They have lost some enzymes in the biosynthetic pathways. Resistant mutants Immobilized mutants Non-pigmented mutants Mutants without capsules Mutants that cannot use sugars Viruses resistant mutants

Mutation types Spontaneous mutations Point mutation A mutation in a base pair Transition purine, or primidine Transversion purine primidine, or primidine purine

Mutation types Point mutation in the ATG codon of ancestral strain results in: If the ATA codon occurs, the tyrosine codon silent mutation If the ATC codon occurs, the stop codon nonsense mutation If the TTG codon occurs, asparagine missense mutation

Mutation types Frame shift mutations, reading pattern shift or frame shift Extraction of a base pair from the DNA (microdeletion) or insertion of a base pair into the DNA (microinsertion)

Translocation of DNA fragments on the genome to a different region of DNA by translocation It was determined that the DNA fragment that was broken by inversion was inverted and adhered to the same region again. Reversal: Point mutations are reversible.

Mutations in RNA genomes: Viruses with genomes consisting of RNA have more (approximately 1000 times) mutations than DNA genomes. The RNA polymerase enzyme in RNA viruses can correct replication errors such as DNA polymerase. However, many repair systems found in DNA genomes are not found in RNA genomes. Therefore, mutations are repaired at a higher rate in DNA genomes.

Mutagens 1. Chemical mutagens Base analogs Timine 5 -Bromurasil Chemicals that react with DNA Nitrous acid (HNO 2) (deamination) Alkylating agents: They alkylate the guanine nitrogen at position N 7. Dyes entering between base pairs such as acridine and ethidium bromide cause microdeletions and microinsersion. 2. Physical mutagens Radiation: Non-ionizing radiation ultraviolet (UV) Rays (260 nm wavelength) primidine dimers Short wavelength rays such as cosmic rays, X rays and gamma rays are ionizing radiation agents. 3. Biological mutagens Transposons, Bacteriophage Mu, Mutagenic DNA repair systems:

Mutagens Physical mutagens Radiation: Non-ionizing radiation ultraviolet (UV) rays (260 nm wavelenght primidine dimers Short wavelength rays such as cosmic rays, X rays and gamma rays are ionizing radiation agents. .

Mutagens Biological mutagens Transposons, Bacteriophage Mu, DNA repair systems with mutagenic effects