<span>Cell division has two checkpoints namely, G1 checkpoint and spindle assembly checkpoint. The checkpoint which determines if division has properly occurred is the G1 checkpoint. At this point, is a damage in the DNA is detected or the has not reach the optimum size, the cell is stopped in G1 and is not allowed to proceed to further process.</span>
He used a simple microscope
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
