Practice question

Transformation involves competent bacteria binding extracellular naked DNA released from lysed cells and importing single strand through competence pseudopilus and Com proteins. No protein coat or phage capsid surrounds DNA; it is deproteinized, often as linear fragments, protected only by its own chemical stability. Once inside, homologous sequences integrate via RecA-mediated recombination replacing recipient allele. Competence develops in Bacillus subtilis, Streptococcus pneumoniae, Haemophilus. Naked nature is proven by DNase sensitivity: addition of DNase destroys transforming activity, unlike phage-mediated transfer which remains DNase resistant and protected.