Bacteria have a single strand.
Humans have X and Y.
Does anything have a T or an O or an L even?
How did I get to be X and Y, what type of animal was first?
No O’s T’s or L’s as far as I know. The Y is not really a Y so much either, as it is something that is not an X.
As for which came first, I would hypothesize the X, meaning that Y chromosomes were an adaptation for sexual reproduction, but I am just guessing.
Actually, the single strand in a bacterium is usually in a loop, so I guess that’s your “O” shape. The Y chromosone is, in some sense, a “defective” X. Incidentally, all of the human chromosones except for the Y are X-shaped, despite the fact that only one or two are named that.
Mitochondrial DNA is circular or O shape and usually called ring shaped. The shape and function (power pack?) ought to be older than anything most of us call animals. We have several of these in every cell, but I’m not too sure of red blood cells.
I did not know about the O chromosomes. Dang prokaryotes (sp?). You learn something new every day!
I do remember hearing something about red blood cells not having mitochondria, but perhaps that is just the power of suggestion from your post.
Red blood cells don’t have a nucleus or nucleic DNA. I’m not sure about mitochondria.
Oh yeah, that might be it. Sheesh, I gotta go back to Zoology 101.
Actually, the most common shape by far is best described as “a tangled pile of spaghetti”. In most organisms, c’somes are only condensed into recognizable shapes for a brief period during cellular reproduction. Most of the time, most of the c’some is relaxed.
I had assumed that X and Y were just designations that had nothing to do with the shape. (Yeah, I know what happens when you assume.) Do the names really relate to the shape? Aren’t almost all chromosomes shaped like the X? I think the Y is just a stunted X with a little extra stuff.