That zoom effect is great. It reminds me of the ZUI (zooming user interface) described in Jef Raskin's book, The Humane Interface. Oh how I wish someone would build a desktop OS with a ZUI.
Best I can tell, they have it wrong. They might be interpreting size differently than I expect but Carbon should be around 220pm and Water around 310pm.
Rough estimates for diameter are based on molecular mass and density; density being variable. I'm curious how they did their calculations.
I'm not sure if it's actually wrong, but rather a function of how they draw atoms versus molecules.
Diameter is a funny concept for atoms and molecules because electrons orbit at different distances around the nucleus probabilistically. The depiction of this carbon atom I think represents this, with the lighter color areas denoting areas of lower probability.
However, drawing such a diagram for a molecule isn't very pretty, because the orbitals for each atom in the molecule overlap. They probably drew the water molecule using intermolecular distances, and then filled in the distances so that each atom was a sphere. In actuality the electrons are found with some probability outside this area.
Actually, as I look at carbon more closely, that's exactly what they're drawing. The inner circle (s orbital) has two yellow dots (electrons) on it, and the outer circle (p orbital) has 4 yellow dots. It does look like they totally ripped off this lady's drawing though: http://www.dorlingkindersley-uk.co.uk/nf/ClipArt/Image/0,,_1...
Clearly they aren't drawing the orbitals for water, which I already stated.
But you're right, carbon is probably too big. Wolfram alpha says the diameter of carbon is 134pm, and we all know WA is right about everything.
The sizes of the atoms in the water molecule have been adjusted to
make them consistent with other atoms depicted in the activity,
although the overall diameter of the molecule is the same.
DNA only exists in the form of chromosomes at particular parts of a cell's life (namely, cell division) and is a highly organized structure consisting of DNA and of proteins.
Neither sperm nor photoreceptors undergo cell division, so for all its existence its DNA exists in an undifferentiated mass inside the cell. DNA is long, but skinny, so it compacts quite nicely.
Stem cells are totipotent and can give rise to any type of specialized cell in your body. Cell signaling induces horribly complex signaling pathways that lead to profound changes in transcription of that cell's DNA.
As an embryo, your gonads start in your chest and, through signals from your brain, end up in your pelvic region.
Erythrocytes (Red blood cells) are a great example of specialization. Before they become erythrocytes they have a nucleus. Their nucleus is ejected, their shape completely changes from spherical to flat-with-a-dimple and they are not a red blood cell. Obviously, erythrocytes cannot divide.
