Answer:
He extracted and observed DNA from white blood cells.
Explanation:
Friedrich Miescher, who is a Swedish Botanist, is the scientist who isolated for the first time. In 1869, Miescher isolated a chemical he called NUCLEIN, which is called Nucleic acid now.
He discovered this so called "NUCLEIN" substance from the nuclei of white blood cells. Nucleic acids are the DNA and RNA we know today, hence, Miescher's discovery was significant to the genetic code as he even agitated for the inclusion of his discovery into inheritance.
A contusion occurs when a strong blow or repeated blows from an object struck the body, crushing the underlying muscle fibres and connective tissues without breaking the skin.
A contusion can vary in severity depending on the object and location of the injury. For example a contusion to the brain may cause a concussion that can cause serious symptoms that require immediate medical attention
