biocukm at okway.okstate.edu biocukm at okway.okstate.edu
Fri Feb 4 12:19:23 EST 1994

My approach is to distinguish three types of chromosomes:  genetic
chromosomes, molecular chromosomes, and morphological chromosomes. 
Genetic chromosomes are the arrangements of genetic loci that are deduced
from recombination frequencies.  Molecular chromosomes are the biochemical
structures, the DNA molecules with associated proteins.  Morphological
chromosomes are the ones that can be seen with microscopes.  Much work in
molecular genetics has been devoted to devising ways to interrelate the
maps of these three types of chromosomes.  I think this conceptual
framework helped my students.  Perhaps it will help yours?

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
>> to a single piece or segment of DNA containing many genes. However,
>> 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
>> 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?

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