× Didn't find what you were looking for? Ask a question
  
  
Top Posters
Since Sunday
12
s
6
j
5
5
s
5
m
5
b
4
p
4
m
4
M
4
i
4
P
4
New Topic  
Dave6 Dave6
wrote...
Posts: 3
Rep: 0 0
3 months ago
Hi,

I realise there is no single answer for this due to the heterogenous nature of mitochondria. The only direct reference I've been able to find was from a researchgate question, which was answered by Barry John Bowman, University of California, Santa Cruz (see attached):

How many ATP synthases in one mitochondrion? Here is a very rough estimate. We examined mitochondria with
an electron microscope and saw the ATP synthases at a density of roughly one per 10 nm (JBC 1989). If a
mitochondrion was a tube with a cross section of 1000 nm, then a single side of one crista would have ~8,000 ATP
synthases. If we assume 20 cristae with two sides in each mitochondrion, then we arrive at 320,000. This is
probably at least the correct order of magnitude.


This seems a very large number, and I am not sure of the step he takes to conclude that 8,000 10 nm ATP synthases (plus I suppose the corresponding electron transport chains) will fit into a single side of a crista. I guess the cristae fold back and forth between the 1um diameter of the mitochondrion?  Still, I wonder if those more expert than me would agree that the above number is at least possible?
Attached file
Thumbnail(s):
You must login or register to gain access to this attachment.
Read 111 times
4 Replies

Related Topics

Replies
Anonymous
wrote...
3 months ago
Let's begin with the obvious. A single mitochondrion is 3-D.

By this source, the surface area per crista is 240 nm × 20 nm × 4 + 20 × 20 nm2 or 1.96 x 104 nm2. This is about three times larger than the surface area of the outer member, 1.98 x 106 nm2, which makes sense because of the cristae folds.

The next obvious this to report is that the ATP synthase enzyme is found embedded on the surface of the cristae membrane.

You mention that ATP synthases is found at a density of roughly one per 10 nm.

Given 1.96 x 104 nm2 = 19,600 nm2

19,600 nm2 divided by 10 makes 1,960 ATP Synthase per mitochondria.
Dave6 Author
wrote...
3 months ago
By this source, the surface area per crista is 240 nm × 20 nm × 4 + 20 × 20 nm2 or 1.96 x 104 nm2. This is about three times larger than the surface area of the outer member, 1.98 x 106 nm2, which makes sense because of the cristae folds.
Think there may be a typo; according to the source the SA of the inner membrane is  5.76 x 106 nm2 whereas the outer membrane is 1.98 x 106 nm2, an increase by a factor of around three as stated.
5.76 x 106 /10 =576,000.  Since surface area > length, then the 320,000 estimate does not seem widely inaccurate.
Thanks for pointing this out.
wrote...
3 months ago
Another source claims

In these cells, the corresponding number of active ATP synthases per mitochondrion ranges from 5000 to just about a hundred. The absolute total number of ATP synthase molecules per mitochondrion, regardless of their activity status, can be up to two orders of magnitudes higher.

Notice the key word, "active"
Source https://iopscience.iop.org/article/10.1088/1478-3975/abf7d9#:~:text=In%20these%20cells%2C%20the%20corresponding,two%20orders%20of%20magnitudes%20higher.
Dave6 Author
wrote...
3 months ago
Again, this backs up the original estimation by Bowman. Good point about the relatively few which are actually working at any one time - if all approx. 1/3 million were active then the concentration of, say, redox molecules necessary to keep feeding the electron transport chains would be pathological/impossible.
Thanks to the 2 posters - both of whom have validated the 320,000 total number of ATP synthases.
New Topic      
Explore
Post your homework questions and get free online help from our incredible volunteers
  297 People Browsing
 466 Signed Up Today
Related Images
  
 1271
  
 3946
  
 151
Your Opinion
How often do you eat-out per week?
Votes: 62

Previous poll results: Do you believe in global warming?