X-inactivation Marks the Spot for Cat Coat Color - HELP??

[dearblondi]

Hello everyone - so I foolishly chose this ( https://www.sciencebuddies.org/science- ... ml#summary ) project for my science class. I know barely anything about genetics or whatever. But I like cats. It's too late to turn back now, so I'm asking for help...

What exactly would the hypothesis be like...? I know I'm drawing lines on cat faces, but that doesn't help anything. I think I wrote this for my hypothesis earlier: "If the X-Inactivation gene causes the colors of a tortoiseshell cat, and they all have similar genes, then their faces will be somewhat similar color-wise."
Now I'm having second thoughts.
I have no idea what the independent/dependent/constant/etc etc would be. I'm totally lost.

I have the pictures of the cats printed out, the lines drawn on their faces, the tables and graphs made, but now I'm to the part where I have to write a paper. God help me.
Or any of you guys, that would probably be easier.

Thank you so much!!
- Casey

[ivyh]

Hi Casey!

You did not make a foolish decision, I promise. Your hypothesis is along the right lines, but it can use some tweaking.

X-inactivation is not exactly caused by a "gene". For an organism to display signs of X-inactivation, they need to have two different alleles that express the same trait. In the case of tortoiseshell cats, They have an Oo genotype, where big O expresses orange fur and the little o expresses black/brown fur. This means that one of the alleles is present on the first X chromosome and the other is present on the second X chromosome. Each cell on the cat has some chance of expressing either the big O phenotype or the little o phenotype.

Now that you know this, your hypothesis can be changed accordingly. You can go along the same lines as you were before and make an educated guess about whether X-inactivation in cats is random or follows some type of pattern. If you are having trouble writing your hypothesis and with indentifying dependent and independent variables, these links should help:
https://www.sciencebuddies.org/science- ... esis.shtml
https://www.sciencebuddies.org/science- ... bles.shtml

If anything is unclear or you need any more questions answered, feel free to ask!