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If post is spelled P-OS-T and most is spelled M-O-S-T, how do you spell the word for what you put in the toaster? Microbial Genetics General Biology SUNY Orange at S. S. Seward Institute It's At The 20! The 10! Can The Flu Go All The Way? by Laura Lorson Tobacco Mosaic Disease Red Neck Bird Dogs Bacterial and viral growth curves Lytic cycle of phage T4 Viral structure Phage Infecting Bacteria • Sorenson animation • T4 Assembly Viral reproductive cycle Adenovirus Reproductive cycle of an enveloped virus HIV infection Couple at AIDS quilt HIV, a retrovirus Smallpox Measles Polio Hepatitis Influenza epidemic Influenza Virus • video Herpes Emerging viruses Deer Mouse – vector for hantavirus Viral infection of plants Tobacco mosaic virus Prion Diseases Kuru Creutzfeldt-Jakob Disease A hypothesis to explain how prions propagate Replication of the bacterial chromosome E. coli E. coli dividing Bacterium releasing DNA with plasmids Plasmids Genetic recombination produces new bacterial strains: Transformation Transduction Conjugation Transformation • The alteration of a bacterial cell’s genotype by the uptake of naked, foreign DNA from the surrounding environment Detecting genetic recombination in bacteria Transduction • Occurs when a phage carries bacterial genes from one host cell to another • Generalized transduction – a small piece of the host’s cell degraded DNA is packaged within a capsid • Specialized transduction – occurs when extra DNA is taken when prophage genome is excised Transduction Transduction Transduction Transduction Conjugation • Transfers genetic material between 2 bacterial cells temporarily joined • F factor – about 25 genes, most required for production of sex pili – Either in chromosome or on plasmid – Episome – any genetic material that undergoes reversible incorporation into a cell’s chromosome • Ex. F plasmid, any temperate phage Bacterial mating Conjugation and recombination in E. coli Conjugation and recombination in E. coli Conjugation and recombination in E. coli Conjugation and recombination in E. coli R Plasmid • R for resistance • Also have genes for sex pili • Therefore can be transferred from one cell to another by conjugation Transposons • Pieces of DNA that can move from one location to another in a cell’s genome • A type of recombination – Chromosome to plasmid – Plasmid to chromosome – Plasmid to plasmid – Chromosome to chromosome (Jumping gene) Barbara McClintock, Ph.D., Nobel Prize laureate Insertion Sequence • Consists of DNA necessary for the act of transposition • Requires a transposase gene • Flanked by a pair of inverted repeat sequences Insertion sequences, the simplest transposons Insertion of a transposon and creation of direct repeats Composite transposon • Extra genes sandwiched between two insertion sequences Anatomy of a composite transposon The control of gene expression enables individual bacteria to adjust their metabolism to environmental change. Regulation of a metabolic pathway Regulation of a metabolic pathway Operon -a unit of genetic function (bacteria and phages) regulated clusters of genes with related functions 1. gene(s) that it controls 2. Promoter region where RNA polymerase first binds 3. Operator – between promoter and the first gene – acts as on/off switch The trp operon: regulated synthesis of repressible enzymes The trp operon: regulated synthesis of repressible enzymes The lac operon: regulated synthesis of inducible enzymes The lac operon: regulated synthesis of inducible enzymes cAMP (Cyclic Adenosine Monophosphate) Positive control: cAMP receptor protein Positive control: cAMP receptor protein
