Cell Cycle Review


What is on the test?

The cell cycle is the life cycle of the cell.  Most of the time is spent in Interphase, but a small part of a cellís life is spent dividing through the process of Mitosis. 

Interphase:  The cell performs regular cell function and it is the longest phase of the cell cycle.  There is a nucleus with a nuclear membrane and the DNA is not visible, it is in the form of chromatin which is long, thin strands of DNA.  The main events of interphase are:

Mitosis is the division of one parent cell into two daughter cells

Mitosis is required for these main reasons:

The four phases of mitosis and the main things that happen in each phase are:





  • chromosomes continue to twist and shorten and become more easily visible and appear to be randomly positioned in the cytoplasm.
  • Spindle fibers form and attach to each chromosome at the centromere
  • The nuclear membrane and nucleolus dissolve into the cytoplasm and are not seen

This is the longest phase of mitosis because of the chromosomes twisting and condensing.







  • The chromosomes are pushed and pulled by the spindle fibers until they are lined up one beside the other in a straight line in the center of the cell.










  • The spindle fibers shorten and this causes a tugging action on the centromeres and it causes the sister chromatids to be separated and pulled to opposite ends of the cell.









  • The chromosomes at each end will Ďbunch upí and a nuclear membrane forms around them.  This creates two nuclei in one cell
  • Cytokinesis (the cell splitting into two cells) begins.  In a plant cell a cell plate of cellulose forms across the middle of the cell.  In an animal cell a protein ring forms around the middle of the cell and pinches the cell membrane until it is pinched into two cells.

This is the shortest phase of mitosis.

Review all notes, labs and questions you answered for this topic to be completely prepared.  Be able to identify each phase from photographs.