Kazu H. answered • 01/07/23
PhD in cancer immunology
a) While both chloroplast and mitochondria inner membrane functions as a barrier to restrict the passage of (unnecessary) molecules between the (cell) cytosol and the interior of the organelle, the inner membrane of the mitochondria also functions to separate areas of higher [H+]. This proton gradient (across the inner membrane) drives the reaction potential for ATP synthesis that is generated through a biochemical process known as oxidative phosphorylation.
c) volume = 4/3pi(radius)^3; surface area = pi(radius)^2
1mm; 4.19 mm^3; 12.57 mm^2; 1:3 ratio (surface area to volume)
3mm; 113.10 mm^3; 113.10 mm^2; 1:1 ratio
- As the radius increases, the volume grows much quicker than the surface area.
d) The inner membrane of the mitochondria and the many folds of the thylakoids are beneficial to the cell since the increased surface area permits greater amounts of chemical reactions to occur without increasing the size or overall volume of the organelle.
If you need further explanation, please reach out.
Kazu H.
Hi Stephen. Not sure how deeply you delved into learning about the electron transport chain, but essentially, because of certain biochemical reactions (occurring via complex I to IV), the inner membrane contains high amount of H+. Under normal conditions, through osmosis, you would observe flow from high to low concentration until the concentration neutralizes. And by this exact process, the build-up of H+ within the inner membrane drives the ATP synthase machinery from H+ flowing into the mitochondrial matrix. So, simply put, you have flow of H+ from high to low concentration. Now, you can imagine that by leveraging osmosis, a cell or an organelle within the cell can utilize these fundamental principles to conduct the movement of various molecules across membranes.01/09/23
Stephen W.
Thank you, Kazu for you help. If you dont mind can you pls help with question b which I forgot to add. (b) Based on the diagram, describe how the structure of these organelles controls movement across the membranes.01/08/23