All living things have a genetic molecule. In prokaryotes and eukaryotes: DNA Even in viruses, genetic material is DNA or RNA Directs day to day operations of the cell Provides instructions for making a new individual passed on to daughter cells during cell division
DNA is “packaged” with proteins. Together, this is called the nucleoid.
Note arrows: supercoiled DNA, when ‘nicked’, does not all unravel. Constrained by DNA packaging proteins.
In Archaea, DNA packaging proteins very similar to eukaryotic histones.
Insertion sequence and composite transposon
Fertility plasmid: genes to make a sex pilus; replicates, and a copy is passed to another cell.
Resistance plasmid: genes that make the cell resistant to antibiotics, heavy metals.
Catabolic plasmid: example, tol plasmid with genes for breaking down and using toluene, an organic solvent.
Some sequences mark the beginning of the information, providing binding sites for proteins.This is followed by the information for making the proteins.
A termination sequence signals that making mRNA should end.
Either DNA strand may contain the gene! Transcription just runs the other direction.
Compare the sense strand of the DNA to the mRNA.
Note that mRNA synthesis will be 5’ to 3’ and antiparallel.
Sigma subunit recognizes promoter region of DNA
The hairpin loop destabilizes the interactions between the DNA, mRNA, and polymerase; U-A basepairs are very weak, and the complex falls apart.
Multiple ribosomes attach to the mRNA and begin translating.
Strings of ribosomes can be seen attached to the mRNA.