Science Buddies: "Ask an Expert"

Good afternoon! I am doing the "X-inactivation Marks the spot for Cat Coat Color" project and I'm a little lost. I made a bar graph at the end of my project like the project guide said to and I am supposed to look for a pattern to see whether or not X inactivation is random or predetermined with respect to orange alleles. What percentage constitutes a pattern for the different color for each face region? Does it have to have 100% or just the majority? I am unsure what I am supposed to be concluding from my results. Also is this an okay hypothesis, "I think that there will not be a pattern in the fur color which will indicate that X inactivation occurs randomly." Thank you!

Hi,

That's a fun project, especially if you can use REAL cats--but internet photos are fine.

Since there are two X chromosomes, if the inactivation is random there will be a 50% chance of one allele or the other being expressed. It's like flipping a coin. I think they should have said to use an even number of tortoise-shell cats or cat photos to make it easier to compare. If your results show about 50:50 (about half the cats) for each color then you can conclude that the inactivation is random.

Sybee

Thank you very much!