MathBench > Probability

Linked Genes and Recombination
Advanced Punnett

Some notation

So if the two genes (one for eyes, one for teeth) are both on the same chromosome, they will also be linked during meiosis. And it turns out to be pretty important HOW the ALLELES are arranged.

We could draw both homologous chromosomes every time we wanted to talk about linked genes:


But, not all geneticists are good artists, so maybe we need an easier notation:

You could write this: Like this (abbreviating the homologous chromosomes as a single line): Or this Or simply

As you know, the two alleles for the same gene are located in the same positions on the homologous chromosomes. So, in our little shorthand notation, we need to make sure that the alleles for a gene are always directly across from each other. Or, that the letters are in the same order on both sides of the slash, which comes to the same thing.

harvey ball, inventor of smiley faces Which of the following are possible chromosome configurations:


This guy is Harvey Ball,
inventor of the smiley face,
for which he was paid $45.