Bacterial Genetic Variation Bacteria have a single circular chromosome containing all of the genes necessary for normal function Small circular pieces of DNA (plasmids) include genes necessary for survival in harsh conditions

Transformation Transformation was originally described in the 1920s by Griffith as he studied streptococcus pneumoniae a bacteria causing a fatal strand of pneumonia. Griffith found that if he exposed non- pathogenic bacteria to heat killed bacteria that they became pathogenic. He said that the non-pathogenic bacteria had been transformed Transformation is the process where bacteria bring in DNA (plasmids) from the environment

Conjugation Certain bacteria (E. coli) can form a cytoplasmic bridge between organisms to transfer plasmids. Was discovered in 1946 Bacteria must have the fertility (F) factor to participate and must be F+ to transfer DNA

Transduction Transduction was discovered in 1951 while studying salmonella. Researchers wondered if salmonella used conjugation like E. coli. It was found that the transfer occurred through a viral vector (T4 phage)

Restriction Enzymes & Plasmids Restriction enzymes were discovered in the late 1960s. In the Early 1970s a graduate student at Stanford proposed in a paper that you could use restriction enzymes to engineer plasmids In 1973 Herbert Boyer et al. published a paper describing how it could be done. In 1976 Boyer founded Genentech and began producing insulin via recombinant plasmids In 2009 Genentech was purchased by Roche for 46 billion dollars and the biotech race was officially ON!

Features of plasmids Origin of replication (ori) Promotor region Side where DNA polymerase can attach and replicate DNA Promotor region Upstream from genes that are transcribed Attachment site for RNA polymerase Transcribes gene to make mRNA Terminator sequence Signals the end of transcription Selective marker GFP green fluorescent protein gene Antibiotic resistance gene bla or ampr