Chromosomes: Unraveling Multiple Representations to Reveal Student Thinking

Presenter - Kim Parfitt, NCBT/3DMD

Friday April 1st, 2:00pm

During the first ten minutes participants will be surveyed to assess their biggest challenge area with respect to student misconceptions about chromosome structure and function, including mitosis.    

Next, foam puzzle chromosomes will be introduced and used to model a round of DNA replication in the cell cycle, resulting in 4 chromosomes.  Models will highlight the position of centromere and telomeres and related to karyotypes.  The processes of mitosis and meiosis will be modeled and compared, to invite inquiry about why the processes are different.   
Whole chromosomes will be related with molecular chromosome details to illustrate how DNA is wound into a chromosome structure.   Nucleosome models will further highlight the wrapping of DNA around histone proteins to compact the genome for replication.  
Participants will be asked to share how they teach about genetic variation in their classes.  Following a discussion of their challenges, we will model variation first using the puzzle chromosomes to generate “crossing over” events and next by using the molecular-detailed expanded chromosomes. 
Participants will be invited to consider genome size in relation to number of chromosomes and numbers of genes in chromosomes, and to reflect on whether the numbers of chromosomes or genome size can correlate with complexity.   
Finally, inheritance of Hemoglobin will be highlighted and modeled.
Throughout the activities, participants will be invited to engage in self-reflection and collaborative discussion.