15.1: Instructor Guidelines

Purpose    

This lab will be very similar to the previous lab on mitosis. Students are introduced to meiosis and simulate the stages of meiosis using pop beads during this lab. Microscope slides, however, are not available for this lab. 

Tasks     

Students will complete the following during this lab:

• Use pop beads to create one pair of homologous chromosomes, with sister chromatids attached using magnetic centromeres.
• Use pop beeds to create one X and one Y chromosome, with sister chromatids attached using magnetic centromeres.
• Use white chalk and additional materials (such as plastic straws) to simulate centrioles and kinetochore/nonkinetochore microtubules.
• Compare and contrast mitosis and meiosis. 

Lab instructors should provide students with an introduction to the cell cycle and the stages of meiosis. A pre-lab reading quiz is also recommended for this lab to ensure students have read the lab manual and have a general understanding of the stages of meiosis prior to coming to class. 

Students tend to have a difficult time understanding the concept of homologous chromosomes. Make sure students include the B and b allele labels on their beads when simulating the stages of meiosis. Students should include the allele labels on each of the sister chromatids.

Introduce students to crossing over in prophase I and independent assortment of chromosomes during metaphase I. Students may want to take pictures of their pop beads at each of the meiotic stages. Ask students to compare and contrast mitosis and meiosis using the pop beads before leaving lab. 

We have found that "testing" students at the end of lab by walking around the room to each group and asking individual students to use their pop beads to simulate specific meiotic stages helps to promote engagement and understanding of the material. 

Remind students to clean the chalk from the bench tops by wiping the chalk dust off of the desks toward the seats/floor and not into the sinks, as this clogs the lab sinks.