# The Naked Scientists Forum

### Author Topic: How many atoms in a cell nucleus?  (Read 5451 times)

#### andymeg

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##### How many atoms in a cell nucleus?
« on: 18/12/2014 00:56:58 »
My 6 year old son wanted to know if an atom and a cell were the same size. I told him cells contain lots of atoms (well molecules) so they must be bigger. He asked how many atoms are in a cell. I fudged and said it depends on the cell.....he said what about the nucleus, how many atoms in the nucleus of a cell? I have no idea. Can anyone help please? He loves big numbers so I think he's going to like the answers.....
Thanks!

#### RD

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##### Re: How many atoms in a cell nucleus?
« Reply #1 on: 18/12/2014 01:13:38 »
... He asked how many atoms are in a cell. I fudged and said it depends on the cell ...

Cells are mostly water , a drop of water has 1021 molecules.

Human cells come in different sizes but they are all much smaller that a drop of water.

So I'd guesstimate 1015 atoms in a typical human cell.
« Last Edit: 18/12/2014 03:02:21 by RD »

#### PmbPhy

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##### Re: How many atoms in a cell nucleus?
« Reply #2 on: 18/12/2014 18:15:35 »
Quote from: andymeg
I fudged and said it depends on the cell.....he said what about the nucleus, how many atoms in the nucleus of a cell? I have no idea.
Actually that is quite correct. There is an enormous difference in the size of cells. Some cells are visible to the unaided eye.

See: http://learn.genetics.utah.edu/content/cells/scale/

That last pages explains that there are about 1014 atoms in a typical human cell. Another way of looking at it is that this is 100,000,000,000,000 or 100 trillion cells.
« Last Edit: 18/12/2014 18:17:53 by PmbPhy »

#### CliffordK

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##### Re: How many atoms in a cell nucleus?
« Reply #3 on: 19/12/2014 09:06:00 »
An interesting side is that some of the largest and most complicated individual molecules are the chromosomes.

A human cell has 23 pairs or 46 total nuclear chromosomes (plus several mitochondria each containing a single chromosome).

Each chromosome consists of essentially 2 very large mirrored molecules, that are "hydrogen bonded" together, plus a few proteins.  So, essentially 92 molecules in each cell determine everything about that cell, and the whole body.

There are, of course, larger molecules called polymers generally built up of repeated elements such as PVC (poly vinyl chloride) plastic, or perhaps diamonds, but they lack the complexity of a DNA strand.

#### The Naked Scientists Forum

##### Re: How many atoms in a cell nucleus?
« Reply #3 on: 19/12/2014 09:06:00 »