Posted by:
Paul Hollander
at Fri Jul 25 13:23:24 2008 [ Email Message ] [ Show All Posts by Paul Hollander ]
Ah, that's mine.
It comes down to saving bandwidth. On these forums there are emoticons like  and abbreviations like ROTFL (roll on the floor laughing). They minimize typing and save bandwidth. That page you put in is just a list of accepted guidelines for making abbreviations for gene names.
Alphabet books start with a is for apple to help make a easier to memorize. In the same way, using a is for albino or p is for pied makes it easier to remember what the a and p abbreviations stand for.
This forum will not accept the plus character, which is the accepted international symbol for the wild type or normal gene. And I haven't figured out how to do superscripts, either. 
An creature only shows the effect of a recessive gene when there are two copies of the gene. A creature shows the effect of the dominant gene is there is either one or two copies of the gene in the gene pair. A ball python is pied only if it has two copies of the pied mutant gene. A ball python looks normal if it has a normal gene paired with a pied gene or two normal genes. In other words, Mendel would say that pied is the recessive gene and the normal gene is the dominant gene. We've gone a bit beyond that classification, but you see it in textbooks still.
The letter P is big and commanding while the letter p is smaller and less impressive. So Mendel would use p for the recessive gene (pied) and P for the dominant gene (normal). Now we would still use p for pied. But p with the plus character for a superscript (p^plus) stands for the normal gene.
The symbol has to be unique. If p is for pied and p^plus is the normal gene, then P is reserved in case another version of the gene appears.
p = pied, a recessive mutant gene
p^plus = the normal version of the pied mutant gene
P = unused but reserved
As both p and P are claimed, then neither can stand for pastel. Pastel is a codominant mutant gene, and both dominant and codominant mutants start with an upper case letter.
Pa = pastel, a codominant mutant gene
Pa^plus = the normal version of the pastel mutant gene
pa = unused but reserved.
The plus superscript really works much better with paper and pencil than in these forums.
By Mendel's convention, the more dominant gene goes on the left of a gene pair, and the more recessive goes on the right of a gene pair. So PaPa^plus stands for a gene pair containing a pastel and a normal gene. And p^plusp stands for a gene pair containing a normal gene and a pied gene.
Those are the basics right there. In the guidelines sheet I went a bit further, but the bells and whistles can be skipped at this time.
Does that help? Post your questions.
Paul Hollander
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RE: punnet squares and genetic terms - Paul Hollander, Fri Jul 25 13:23:24 2008
