Presentation on theme: "Microbial Models Chapter 18. The Genetics of Viruses Bacteria and viruses often used - reproduce quickly, have unique features. Bacteria - prokaryotic."— Presentation transcript:
HIV enters host cell, reverse transcriptase synthesizes double stranded DNA from viral RNA. Transcription produces more copies of viral RNA - translated into viral proteins - self-assemble into virus particle and leave host.
Sometimes damage from virus is irreversible (polio) Symptoms associated with viral infection result from body’s own efforts at defending itself. Modern medicine developed vaccines - harmless strains of virus that stimulate immune system.
Plant viruses Plant viruses can stunt plant growth, diminish crop yields. Can be inherited from parent plant or caught from other plants. Plant cells connected by plasmodesmata so virus can spread quickly.
The Genetics of Bacteria Bacterial genome - double- stranded, circular DNA molecule. Tight coiling of DNA results in dense region of DNA (nucleoid) not bound by membrane. Many bacteria have plasmids - smaller circles of DNA.
Genetics recombination also causes diversity within bacterial populations. Recombination - combining of DNA from 2 individuals into 1 genome. Transformation - alteration of bacterial cell’s genotype by uptake of foreign DNA from environment.
Conjugation transfers genetic material between 2 bacterial cells that are temporarily joined. One cell (“male”) donates DNA; “mate” (“female”) receives genes. Male determined by presence of F factor.
Gene expression in bacteria Operon - 3 elements: genes that it controls, promotor region where RNA polymerase first binds, and operator region between promotor and 1 st gene that acts as “on-off switch”.