The scale of things

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Ivan Delgado
Ivan Delgado's picture
The scale of things

For anybody out there that enjoys dealing with the size and weight of things, here is a table I put together a while back for a training course on molecular biology. It is a good way to remember the SI symbols and which one comes after which (don't want to confuse a picogram with a femtogram).

Scale
SI prefix
Amount
SI symbol, example

1.0
gram
100 (1)
25 g, 1 mouse

0.001
milli- gram
10-3
1 mg, 1 mosquito

0.000001
micro- gram
10-6
1 ug, 3 grains of sand

0.000000001
nano- gram
10-9
1 ng, 1 human cell

0.000000000001
pico- gram
10-12
6.7 pg, 1 human genome

0.000000000000001
femto- gram
10-15
667 fg, E. coli cell

0.000000000000000001
atto- gram
10-18
50 ag, 1 virus particle

0.000000000000000000001
zepto- gram
10-21
1.5 zg, 3 nucleotides

0.000000000000000000000001
yocto- gram
10-24
1.67 yg, 1 proton

 
 
 
 

Also, one Dalton (Da) (a single hydrogen atom) weighs 1.67 yg, or 1 atomic unit.
(also, if anyone knows how to reduce the space between my first paragraph and the table do please let me know :) ).
 

cfish
cfish's picture
Nice table...I never thought

Nice table...I never thought about anything after femto.
Also, tried to edit your post to reduce the space but didnt work.

Ivan Delgado
Ivan Delgado's picture
Thanks for trying to fix it :

Thanks for trying to fix it :).
Most of the time in biology we never have to think about thing beyond femto, yet not too long ago I developed a real time PCR assay to detect a virus and the assay was sensitive all the way to the attogram level. When you play around with real time PCR these days, you may end up looking at these very low levels of material. When that happens your ability to come across as a nerd in conversations skyrockets ;).