The study of E. coli led scientists to new experimental designs for studying operons. How did scientists begin studying operons? They began to study cell division of cells under a microscope to determine how operons worked. They began testing different chemicals on E. coli to determine the number of operons present. They began reading the genome sequence of organisms to determine the number and organization of operons.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

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