Friday, May 02, 2014

epigenetics, calico cats, and a quote for the day


Having added what I've learned in Epigenetics this week to what I knew before I started the class, I knew what this slide meant, except for "gastrulation".........

One of the things I love about watching taped lectures is that I can pause them and go look things up.  You can see what I gleaned from Wikipedia about gastrulation at the bottom of the image above (as always, click on an image if you wish to embiggen it).

And now, here's quote I promised, as extracted from the Wikipedia article on gastrulation:

Lewis Wolpert, pioneering developmental biologist in the field, has been credited for noting that "It is not birth, marriage, or death, but gastrulation, which is truly the most important time in your life."

Now you know.

Now, taking a tangent from our discussion of gastrulation.......

The results of X inactivation are visible on calico cats.  The genes for coat color, in cats, are on the X chromosome.  A cat may inherit one coat color from her mother, and a different coat color from her father.  When the female embryo is about 4 days old, one or the other of her X chromosomes is inactivated. As cells grow, divide, grow, divide, groups of cells with the same active X chromosome (from mother OR from father) get larger and larger.  By the time the cat is born, a female cat whose parents have two different coat colors has a coat with patches of different colors.

I knew calico cats were always female, but I never knew why until I watched this video a couple of weeks ago.   (It's kinda long, but it's pretty accessible, I think.   A person doesn't have to understand all of it to be entranced by it........)


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