Laboratory Investigation:




When an organism grows, its cells grow.  But cells cannot increase their size forever.  When they get too big, they divide in two.  This is called cell division.  One type of cell division is called mitosis.  During mitosis, an exact copy is made of all the genetic information in the cell.  This is important because the genetic information has been passed down for generations over millions of years.  The organism does not want to lose any of that information.  The information is stored in the nucleus of the cell.  When a cell is about to divide it is possible to see the chromosomes. 

Below is a diagram showing a cell with some chromosomes.  Answer the questions after the diagram and then click on the scroll-down box with the ??? question marks on it.  It will give you the answer.  You can use these questions as a practice test.  Write your answers somewhere and come back to check them. 

  • How many chromosomes are shown in this cell?

  • How many pairs of chromosomes are there?

  • What do the red chromosomes represent?

  • How many chromosomes did this cell inherit from its father?

  • Did this cell get just as many chromosomes from its mother?

Below is the same cell;  the only difference is that the chromosomes have been lined up to see the pairs more clearly.

  • Could this be a representation of a human cell?

  • Explain:

  • How are the pairs matched up?  What criteria are used to decide which chromosomes go together in pairs?

  • What does the cell need to do to these chromosomes before it can divide to make two cells?

Go to the next page to see the next step.


Next page >>>


All photos, diagrams and animations by A. Damon,
based on a magnetic chromosome model by Pierron scientific equipment.