Updated: Oct 23, 2019
I took these pictures during our latest microscopy lesson, where we observed the different stages of mitosis in the cells from an onion root tip 😄 I have put the pictures of the stages in the order that they happen. The metaphase cell may be difficult to notice, but it is in the bottom of its picture 😅
Mitosis is the second part of the cell cycle, and is defined as the duplication
of the nucleus into two identical daughter nuclei with identical sets of chromosomes.
It is composed of four stages:
First is prophase, during which DNA supercoils, the nucleolus disappears, the nuclear membrane disintegrates and the spindle microtubules start to form (they will be finished by the end of prophase).
Next is metaphase, during which spindle fibres bind to the centromeres of the chromosomes and pull them towards the equator of the cell. By the end of metaphase chromosomes will be completely aligned in the middle of the cell.
Third is anaphase, which is the shortest phase. During this phase the spindle microtubule fibers contract and shorten, first pulling apart the centromeres and then pulling the now separated chromosomes to opposite ends of the cell.
Last, but not least: telophase. During this phase, the cell prepares for cytokinesis (the separation of
the cytoplasm to form two new separate cells). The chromosomes have now reached the poles, the nuclear membrane reforms at each pole and a nucleolus appears in each new nucleus. Now the spindle microtubules disintegrate, and the cell elongates in preparation for cytokinesis.
Image credit: https://www.google.com/url?sa=i&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjy3ZfplrPlAhVDtZ4KHcnpAfoQjhx6BAgBEAI&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3Df-ldPgEfAHI&psig=AOvVaw3pt2Tu8iqwWbedwPPA4KNV&ust=1571947469895131
All images taken by the International Baccelaureate student Julia Mircan