WHAT IS A CHROMOSOME

klier at cobra.uni.edu klier at cobra.uni.edu
Thu Feb 3 19:09:59 EST 1994


In article <1994Feb1.172556.1 at cc.uvcc.edu>, parkerbr at cc.uvcc.edu writes:

> As a teacher of genetics, I face an often frustrating task of defining for my
> students  what is meant by a chromosome. Most would agree that the word refers
> to a single piece or segment of DNA containing many genes. However, most
> textbooks refer to the structure found in the early stages of mitosis,
> containing _two_ pieces of DNA held together by a centromere also as a
> chromosome. Since this is really just a temporary structure made by the cell as
> a way to accurately divide the DNA, wouldn't another name be more appropriate,
> and less confusing? Most post-biology students probably still think that those
> "X"-shaped structures are found in all cells whether dividing or not.
> Any thoughts on the matter?

A number of us who taught in multiple sections of a non-majors' bio class
had similar frustrations... we came up with a new term: "replicated
chromosome" for this, and found it cleared up a number of conceptual
difficulties for the students.   Incidentally, we do NOT use interphase/
prophase/metaphase/anaphase/telophase when talking about mitosis until
the students have demonstrated that they can describe the behavior of
chromosomes during mitosis.  Students have since displayed increased 
ability to comprehend later materials on mitotic and meiotic abnormalities...
we believe they were memorizing IPMAT and then thought they "understood"
mitosis.  An additional benefit of banishing the IPMAT terminology to
a later lecture is that they now seem to understand mitosis as a
continuous process, not as a series of freeze-frames.

The people who have taught in the general biology class for majors and
have also taken the same tactic report it works well for those students
also with the following modifications:  students are warned that they
won't find the term "replicated chromosome" in their text, but we find it
convenient for learning, and we explicitly forbid them to use the
IPMAT terminology until they have displayed understanding of the process.

Kay Klier  Biology Dept  UNI
  



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