• What are important characteristics of bacteria?
• small, easy to grow in extremely large numbers; very useful to have lots of
• grow very quickly; typical generation time < 30 min
• small genome: E. coli ~5 Mbp
• many antibiotic resistance and auxotrophy markers
• E. coli workhorse of molecular biology
Ecoli is the bacteria that lives in the gut and is isolated a long time ago and used in
You can grow them much more than any other organism like round worms
In genetics, we need to look through generations of individuals and bacteria has a
generation of around 30 minutes.
Extremely powerful tool to modify DNA
Most labs use E Coli to manipulate DNA
One way is liquid culture
Start from a flask and use a medium that has what the bacteria needs to grow
Put bacteria in it and have 30C and shake it and come back the next day
The cloudy medium isn’t full of bacteria
The other way are in the plates
The white dots are colony of bacteria
Each dot is supposed to be a single cell of a bacteria
These single cells separate it at the right diluted
Incubate it at 37C
The bigger white dots are the colonies of bacteria. Each white dot is derived from a single
founder of a single bacteria.
This is useful if the single bacteria is a mixture of single types.
But now it is neatly separated for us.
You have gone from a mixture to groups of separated clones.
Haploid – only one allele in any given individual
One circular chromosomes and has other chromosomal D