Expert: Ralph Salier-Hellendag - 11/4/2009

Question
Which is heavier:  Mitochondria or chloroplast?

Answer
Hi Diana,

This is a very hard question to answer because there is a great deal of diversity in the size of these organelles.  Mitochondria can be from .2 to10 micrometers in size while Chloroplast can be from 2 to 10 micrometers in size.  So there is a fair amount of overlap.  Mitochondria tend to be a little thicker on average while Chloroplast are a thinner on average.  So, on the lower end of the range, the Chloroplast would tend to be heavier while on the upper end of the range the Mitochondria tend to be a little heavier IF size equates to weight.  

I was unable to find any descriptive data on the weight of these tiny cellular structures.  

Here are two of the websites I looked at:
en.wikipedia.org/wiki/Mitochondrion
en.wikipedia.org/wiki/Chloroplast