Question

What evidence supports the theory of endosymbiosis?

Does diffusion happen faster in a membrane rich in saturated or unsaturated fatty acids? Why?

Diffusion may occur via simple movement across the membrane or via carrier proteins. Furthermore, various types of carrier proteins may be involved. Why the need for more than one mechanism?

Answer 1

The evidences that supports the endosymbiotic theory -

• Both mitochondria have their own circular DNA just like the prokaryotes .
• Born mitochondria undergoes division by binary fission , which is similar to the prokaryotes .

Diffusion through saturated fatty acids will be faster as compared to unsaturated fatty acids .

This is because the saturated fatty acids have longer chains and less double bonds , which is an important factor in determining the fluidity of the membrane .

There is a need of more than one type of transport mechanisms because different molecules have different requirements for getting transported across the cell membrane .

Some are lipid soluble , so they cross the lipid bilayer easily , but some are lipid insoluble, so they need a transport protein or a carrier to move across.

Some molecules along other molecules - symport and some are transported in opposite direction of other molecules - antiport .