APBI 200 Lecture Notes - Deoxyribonucleotide, Cell Nucleus, S Phase
Document Summary
A strain is a population of genetically identical individuals. Strains that affect humans vary in their virulence their ability to cause disease and death. Virulent strains cause disease, avirulent (benign) strains do not. A liquid or solid that is suitable for growing cells (a petri dish can contain nutrient-containing medium) Griffith in the 1920s did experiments to develop vaccine against streptococcus pneumoniae bacterium. Griffith worked with strains identifiable by eye when grown on a nutrient- containing medium in a petri dish. On a solid medium, cells from the nonvirulent strain form colonies that look rough (r) ; cells from the virulent strain form colonies that look smooth (s) Griffith injected mice with r strain, s strain, heat-killed s strain, and r strain with heat-killed s strain. Found that mice died when injected with s strain, and with r strain with heat- killed s strain; mice did not die with r strain nor heat-killed s strain.
