To disprove spontaneous generation, pasteur used swan-necked flasks to allow entry of air to the boiled broth while blocking contaminating dust. this was his treatment flask. what do you suppose he used for a control?

Pasteur produced a nutrient broth and placed equal amounts of it in two long necked flasks. One flask had a straight neck (control) and the other had a swan shaped bent neck (being tested). He boiled the broth in both the flasks to kill any living organism that might be surviving on it. The two flasks were then left in the open air of the room to cool down. After several days passed, Pasteur noticed that the broth in the straight necked flask had changed its color but the swan necked flask didn't. From this observation he was able to conclude that the straight necked flask had let the organisms enter the flask and contaminate the broth. The swan necked flask blocked the entry of the organisms from the open air and thus remained unaffected.

interphase

the period of cell growth when the cell synthesizes new molecules and organelles. the cell is not dividing and it constitutes the majority of the time spent in the cell cycle

prophase

changes occur in the nucleus and cytoplasm. the chromatin condenses to form structures (sister chromatids) visible with a light microscope and the mitotic spindle begins to form, but the nucleus is still in tact

prometaphase

the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the sister chromatids

metaphase

all the cell's duplicated chromosomes are lined up at an imaginary plane equidistant between the poles of the mitotic spindle

anaphase

begins when sister chromatids separate from each other and ending when a complete set of daughter chromosomes arrives at each of the two poles of the cell

telophase

the daughter nuclei form at the two poles of a cell

cytokinesis

the division of a cytoplasm to form two separate daughter cells. usually occurs during telophase during mitosis. this and mitosis make up to mitotic (m) phase of the cell cycle