Ask A Scientist© Molecular Biology Archive

name         Kathleen
status       student
age          15
 
Question -   When a friend and I extracted DNA from 10 different
fruits and vegetables for our Honors Bio project, we noticed that there
was a lot of variation in the amounts of DNA yielded from each.  Why do
some things give more DNA than others?

There are several reasons that you find different amounts of DNA in each
sample.  One is that the number of cells per gram will be very different
between different species of plants.  Even within the same plant, the
leaves will have different sized cells than in the roots or a fruit.  But
each cell within a plant will (usually) carry the same amount of DNA as
every other.

The other neat thing is that many commercial plants are polyploid.  That
means they carry more than the usual two sets of chromosomes.  While
animals are usually diploid (two sets of chromosomes -- one from mom, one
from dad), plants can be just about anything.  For example, commercial
wheat is hexaploid (six complete sets of chromosomes), and bananas are
triploid (three sets).
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Christine Ticknor
Ph.D. Student
Yale University
New Haven, Connecticut
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