TITLE:  Genetics: Meiosis
 

GOALS
The purpose of this lesson is to introduce the students to the process of meiosis and to help them understand how it differs from mitosis.

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SPECIFIC OBJECTIVES

• The student will understand the meiosis occurs only in the sex cells and involves two divisions, as compared to one division in mitosis.
• The student will know the stages of meiosis and understand what is occurring in each step.
• The student will understand the purpose of chromosomes in the process of meiosis.
• The student will understand that meiosis is essential for the process of reproduction.

BACKGROUND
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SOLs COVERED

LS  2

The student will investigate that all living things are composed of cells. The key concepts included with this lesson are: cell division and the processes of mitosis and meiosis.

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DEMONSTRATIONS AND EXHIBITS
Materials needed: transparencies with illustrations of the processes of mitosis and meiosis.

1. The stages of mitosis and meiosis.

• Compare the stages of each process, emphasizing the extra division in meiosis and the fact that meiosis results in a cell have half the originial number of chromosomes.  These resultant cells are almost exclusively sex cells (gametes).  It amy be appropriate to explain that the combining of two gametes re-establishes the original chromosome number.

INTERACTIVE EXERCISES
Materials needed: two different colors of gummy worms, blank paper

1. Meiosis simulation with Gummy Worms.

• Student break up into groups of two.  Each pair draws a circle about 15 cm in diameter on a blank sheet of paper.  Each pair receives eight worms (four of each color).  They place two worm of each color into the circle, presenting a parental cell about to undergo division.
• Prophase - chromosome replication.  Each pair places another worm of the same color next to the worms in the circle.
• Metaphase - chromosome alignment.  The students line up the color pairs along the central axis.
• Students draw two new circles side-by-side.  Students move two of the color pairs into one circle and the remaining two color pairs into the other circle.  This completes Meiosis I.
• Students draw four new circles on a new sheet of paper.  Students take one worm from each color pair in the Meiosis I circles and moves them into one of the new circles.  This should result in two worms in each circle, representing the end products of Meiosis II - cells with half the number of chromosomes as in the parent cell.

INTERESTING EXAMPLES
 

OTHER RESOURCES
 

Literature	.
Video	"Genes" by Mr. Science
Related Web Sites	.

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