Bacterial Genetics & Transformation Preparation for the pGlo Lab

Bacterial Genetics & Transformation

Preparation for the pGlo Lab

Bacterial Genome• Circular• Little protein• Condensed DNA = nucleoid

Mutation as a Source of Genetic Variation

• Bacteria reproduce asexually by binary fission• Mutation can increase genetic diversity when

reproduction rates are high b/c of short generations (fitness)

Genetic Recombination• Combining DNA from two sources • Usually two bacterial cells or bacteria & a phage• http://www.youtube.com/watch?v=MRBdbKFisgI

Conjugation & Plasmids

• Conjugation: Direct transfer of genetic material b/w bacterial cells via a sex pilus that attaches to the recipient

• http://www.biologie.uni-hamburg.de/b-online/library/micro229/terry/images/anim/Fmating.gif

Plasmids

• Small circular piece of DNA, separate from bacterial chromosome can be reversably integrated into the bacteria’s chromosome

• Confer favorable traits

pGLO Bacterial Transformation Lab

• Transform e. coli bacteria• Move genes from one organism to another

with the aid of a plasmid

P GLO Plasmid• pGLO plasmid encodes the gene for GFP and

a gene for resistance to the antibiotic ampicillin

• pGLO gene is turned on (regulated) in the presence of the sugar, arabinose

Gene Regulation

• Not all genes are “on” all the time—why?• Promoter: Located on the DNA template

where RNA polymerase begins transcription of Mrna

• Operon: A cluster of genes controlled by a single promoter

Arabinose Operon

• Bacteria produce three enzymes (araB, araA and araD) to break down arabinose sugar

• The “ara” genes are clustered together and controlled by a single promoter (Pbad).

Expression of Green Fluorsecent Protein

Predict Which Plates Will Glow