Name: Heather M.
My teacher tells me that you can not write the little
letter frist in the combinations. For example tT. But then I read you
can in my Biology Book but he still says no. So can you write it tT or
is it Tt?
Heather, you will find that it will be very confusing for you if you write
the little letter first. The convention of the big letter first makes it
easier to read and interpret results from the Punnett square, as well as
determining the phenotype from any genotype. The only time that I've ever
seen the little letter first as being acceptable is when one is trying to
show exactly which allele came from which parent. For example, if you cross
Tt and Tt, there are two ways you get offspring that are Tt: one where the
mother donates the t, and one where the father donates the t. Writing the
little letter first would suggest that the mother donated the t - it would
be useful in some probability problems with genetics.
Does that make sense?
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Update: June 2012