Read the pages indicated by G-10 and study behavioral objectives  22 and 23 .  Meiosis is similar to  mitotic cell division  studied earlier.  The difference between meiosis and  mitosis is that there are two sets of nuclear divisions during the meiotic cell cycle. The first process (meiosis I)  includes  a reduction of chromosomes.  The second  process (meiosis II) is a normal mitotic division as studied earlier; however,  no DNA replication  occurs  prior to prophase II. The overall effect of meiosis is the reduction in chromosome numbers of a diploid cell by one-half. 

Examine the figure below. Even more important this reduction of chromosomes is not random, but is separates the homologous chromosome pairs of a diploid cell into four cells which contain only one of each homologous pair (haploid cells). This concept is very important. In your notes draw figures representing diploid and haploid cells. 
 
 
1. Click here for the definition of diploid cells and haploid cells.  click 
 
 
 
 
 
 

A cell preparing  to undergo meiosis  will pass through the S and G2 stage similar to the mitotic cell cycle during the interphase stage. Remember that during the S stage DNA replication occurs.  The cell than moves into the first meiotic phases which are divided into four stages similar to that of mitosis - prophase I (chromatin forms into chromosomes) , metaphase I (chromosomes line up along an equatorial plate), anaphase I (chromosomes are pulled to opposite poles) and telophase I (chromosomes reform back into  chromatin forming a nucleus and cytokinesis occurs forming two cells  with each cell containing one of  each homologous pair of chromosomes).  This process  is called reduction  division. The second  meiotic process is also divided into four stages - prophase II , metaphase II, anaphase II and telophase II. Since both cells which are formed during meiosis I undergoes this process the end result will be a total of four cells with each cell containing one of  each homologous pair of chromosomes. This process is a normal mitotic division with no DNA replication prior to prophase II. 
 
 Examine the figures below. Draw these cell cycles in your notes showing a single diploid mother cell being transformed into four haploid daughter cells. Note: There is no synthesis stage "B" during the second meiotic cell cycle. 
  
Read in your text the description for   the eight  phases of meiosis (G-10).  Write in your notes  a description of what occurs to the following structures during  each of these  phases:  chromatin, chromosomes, centrioles,  nucleoli,  nuclear membrane, spindle apparatus (spindle fibers), centromeres, tetrads. These phases are discussed in the next lesson. 

In your notes draw  a cell containing  six homologous pair of chromosomes  during interphase as it appeared when you were studying mitosis. 

2. Click here to  compare your figure to the correct answer.  click 
 
 
 

3. The cell in the above figure represents a diploid or haploid cell? 

Press here to check answer.  press 
 
 
 

 
 
4. The cell represented in the figures above is in which stage of the cell cycle? 

                            a) G1                                             b) G2 
 
Press here to check answer.  press 
 
 
 
 

5. Draw this cell with its chromosome compliment as  it would appear during the G2 stage. 

Press here to check answer.  press 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Click here to study the phases of meiosis.  click 
For information on how to use this page, go to How to Use This Site.