A bacterial cell usually contains a single loop of DNA that is located in the cytoplasm of the cell and is not surrounded by a nuclear membrane. Some bacteria have additional loops of DNA called plasmids. Plasmids can be used for genetic engineering because DNA from other organisms can be spliced into a plasmid loop. For example, scientists in the late 20th century discovered a way to insert the portion of human DNA that codes for the protein insulin into plasmid E. coli bacteria. Which statement best explains why these genetically modified bacteria have been useful to society? A. Human diabetics are now more resistant to bacteria

B. The bacteria are resistant to human diabetics

C. The bacteria can now make their own insulin

D. the bacteria are used to produce cheap insulin.

A is the correct answer.

because for the treatment of one type of diabetes insulin should be provided but isolation of insulin and production is so costly.

but as DNA recombination has developed we can use bacterial replication system to produce insulin. they replicate very fast so large amount of insulin will be produced and then it can isolated.

but we also know that insulin of bacteria needs some modification before it can be used in human.

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before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.