You plate colonies of E. coli with the lac operon genotype of I-P+O+Z+CAP+ on 1) a medium containing only glucose, and 2) a medium containing only lactose. You isolate mRNA from bacteria from each medium and do a Northern blot with a probe for β-galactosidase. Draw the results.

A complete collection of single-use and high-throughput electrocompetent and chemically competent E. coli

Choosing the ideal competent cells for your cloning applications and workflows is a critical component of success. Aspects to consider when selecting your competent E. coli strain include:

Transfection method – chemical versus electroporation

Transformation efficiency – bacterial strain and genotype

Downstream application – protein expression, library production, general cloning

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the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.