Short answers, pulled from the story.
Hugo von Mohl described cell division in the green algae Cladophora glomerata in 1835. He stated that multiplication of cells occurs through cell division and published this observation in Notes and memoranda: The late professor von Mohl within the Quarterly Journal of Microscopical Science.
Walther Flemming coined the term mitosis in 1882. The word derives from the Greek word mitos meaning warp thread.
During prophase which occurs after G2 interphase, chromatin fibers condense into discrete chromosomes that are typically visible at high magnification through a light microscope. Each chromosome has two chromatids joined at the centromere and gene transcription ceases until late anaphase to early G1 phase.
Animal cells generally undergo open mitosis where the nuclear envelope breaks down before the chromosomes separate. Fungal cells generally undergo closed mitosis where chromosomes divide within an intact cell nucleus.
Nondisjunction occurs when sister chromatids fail to separate during anaphase. One daughter cell receives both sister chromatids resulting in trisomy while the other cell receives none resulting in monosomy.