microbial genetics

• Horizontal gene transfer is the process of a current living bacteria acquiring new genetic material. 
• Generalized transduction


  A bacterial host cell is infected with either a virulent or a temperate bacteriophage engaging in the lytic cycle of replication
• If the DNA (from the first bacterial host cell) is incorporated into the recipient's chromosome


  The genes can be expressed
• Horizontal gene transfer is the process of a current living bacteria acquiring new genetic material.
• Conjugation - a major horizontal gene transfer mechanism through which DNA is transferred from a donor to a recipient bacterium by direct contact.
• The process of transformation also allows a bacterial cell to acquire new genes, but it does not require cell-to-cell contact. the process requires a donor cell that at some point lysed and released naked DNA to the environment. The recipient cell is one that is capable of taking up the DNA from the environment and incorporating it into its own genome, where the cell is described as being competent.
• There are mechanical and chemical means of encouraging a cell to pick up DNA from the environment, but natural competence is determined genetically.
• Transduction involves the use of a virus, a bacteriophage, to act as a conduit for shuttling bacteria genes from one cell to another, thus negating the necessity for cell-to-cell contact.
• two different types of transduction: generalized transduction and specialized transduction.
• Specialized transduction can only occur with temperate bacteriophage, since it involves the lysogenic cycle of replication.
• Molecular Recombination - Genetic transformation can be transferred horizontally between cells of the same generation
• Transposable Elements or "jumping genes": Can be responsible for the activation or inactivation of genes within an organism. They are designed to move from one location to another within a DNA molecule by a process known as transposition.
• The simplest transposable element is an insertion sequence (IS), which contains the transposase and IRs of varying lengths.
• A transposon typically contains additional genes, with the exact type varying widely from transposon to transposon. A transposon can be removed from one location and relocated to another (the cut-and-paste model), a process known as conservative transposition. Alternatively, it can be copied, with the copy being inserted at a second site, in a process known as replicative transposition.
• expression - genetic information is used within a cell to produce the proteins needed for the cell to function
• replication - genetic information can be transferred vertically to the next generation of cells