In Science, we have a lesson that covers basic inheritance. We studied about Mendel's experiments on peas. And, we have the monohybrid cross and dihybrid cross. And for the preliminary exams, we were asked to explain dihybrid cross for 5 marks.

But, I didn't remember it that well, so I couldn't do it. However, it bugged me a lot, so, I tried it out when I came home.

Dihybrid was a piece of cake, nothing too difficult. My curiosity wasn't satisfied with dihybrid. And just for the heck of it, I decided to try the same with 3 traits. It took a while to put it together and the result was fulfilling.

I could even work out a pattern for the number of gametes, the number of distinct phenotypic results and the number of distinct genotypic results.

Of course, you can't be too sure with the pattern until you check it thoroughly. To do that, I tried doing the same with 4 traits. And sure enough, the pattern applied to it as well.

If anyone's curious,
Number of gametes for the F2 generation = 2 raised to n.
Number of 'observations' you get from the Punnett Square = 2 raised to 2n. (Doesn't take a rocket scientist to figure that out.)
Number of distinct phenotypic results = 2 raised to n.
Number of distinct genotypic results = 3 raised to n.
where n = number of traits.


And after finding and verifying the pattern, I was curious as to what it would be if the number of traits was 10.

Well,
Number of gametes for the F2 generation = 1,024.
Number of 'observations' = 1,048,576.
Number of distinct phenotypic results = 1,024.
Number of distinct genotypic results = 177,147.

Sadly, I can't do that on paper. And, my concentration isn't good enough to do that. So, I've been working on a program which would be able to generate a Punnett Square, and count the number of distinct phenotypic as well as genotypic results. There have been a lot of bugs in the first step itself, that is, inputting the number of traits and selecting a keyword for each.

I don't know how long it would take to finish the entire program. Or if I can even do it, but, it's certainly fun to try and come up with a way to make this possible.

For now though, here's trihybrid cross.



Just in case you want to zoom in, click here.

It's messy. Pencil is not my friend, the lead kept breaking.

Sadly, I couldn't capture the quadhybrid cross, it's even messier than this table and it's 4 times bigger.