Why do some organelles have double membrane?

Answer 1

When the surface area of the membrane is enlarged, then the rate of diffusion (think of it as the rate of which materials move in and out of the organelle) also increases, making the transfer of nutrients and waste quicker. However, as the surface area increases, so must the volume increase. The ratio, then, between surface area and volume decreases.

Sound weird? Take this for an example: a 1cm cube has a surface area of 6cm^2, and a volume of 1cm^3, for a surface area to volume ratio (SA:V) of 6:1, or 6. A 2cm cube, however, would have a surface area of 24cm^2 and a volume of 8cm^3, for a SA:V of 24:8, or simplified to lowest terms and converted into a whole number, 3. As you can see, the SA:V is constantly decreasing as volume and surface area increase.

This poses a problem to the organelle, because if it was simply going to grow bigger, then its SA:V would decrease, and there would eventually be so much volume that the rate of diffusion cannot keep up with the amount of stuff it has to go through.

A work-around for the cell would then be to increase its surface area as much as possible while increasing its volume as little as possible.

Thus, the need for a folded membrane!

Answer 2

Some organelles have double membranes so as to allow oxidative phosphorylation which is made possible by a proton gradient. Some of the good examples of such organelles are chloroplasts and mitochondria.

Answer 3

The structures of cellular organelles are related to their functions.

Answer 4

See here: http://wiki.answers.com/Q/What_advantage_of_highly_folded_membranes_are_in_a_cell

Answer 5

as the particles on the outer cell wall are hot and melt the side and diffusion happens slower

Answer 6

It conserves space, which is also the reason our brains have crevices.

Answer 7

Think about it. If we had one organ, would we survive? No. All the organelles work together to keep the cell alive.

Answer 8

to increase surface area.