Question

8. The movement of protons out of the mitochondrial matrix establishes an electrochemical H gradient across the inner mitochondrial membrane. The electrochemical potential of this gradient is harnessed to synthesize ATP. This is known as the (A) Hydrophobic effect IqChemiosmotic theory (B) Acid catalysis (0) Michaelis-Menten mechanism _9. Which of the following statements about mitochondria and their lon and metabolite transporters is FALSE? (A) Controlled impermeability of the inner mitochondrial membrane to most ions and metabolites allows for the generation of lon gradients across the barrier and for the compartmentalization of metabolic functions between cytosol and mitochondrion. (8) Electron-rich NADH from the cytosol can be transported into mitochondria directly (C) ATP-ADP translocases have a single nucleotide binding site that can alternate its orientation to face the mitochondrial matrix side as well as the side of the cytoplasm. (D) The outer mitochondrial membrane contains porins, which are proteins that permit the free diffusion of molecules up to 10 kDa. (E) Mitochondria have extensively invaginated inner membranes: these invaginations are cristae and their presence is proportional to the respiratory activity of the cell 10. The Fife ATPase is an excellent example of the ATP synthase in mitochondria. It operates according to a binding change mechanism, where "O" - open, 1-loose, and "T tight. Below are some statements about this mechanism L ADP and enter the site in the "O state. II. ADP and enter the site in the lº state. itt. Once ADP and are bound to the active site, the protein closes around them, putting the site in the state. Once ADP and are bound to the active site, the protein doses around them, slightly, while it is in the l'state. The enzyme then changes shape again and forces ADP and together at the state. VI. The enzyme then changes shape again and forces ADP and R, together at the state. VII. The active site will recycle back to the "L" state and release newly synthesized ATP. VIII. The active site will recycle back to the "O state and release newly synthesized ATP. Which order of statements is correct? (A) I IV VIII (B) IIIVV (C1N1V1I (DIV-VI-VII N. 11. Please draw a flowchart describing how electrons travel through complexes and other such transfer molecules in electron transport if their source is NADH. 2 pts) 12. Please draw a flowchart describing how electrons travel through complexes and other such transfer molecules in electron transport if their source is FADH. (2 pts)

Answer 1

8 ANS: Chemi-osmotic hypothesis
Just know about it, there is not much apart from telling that it was proposed by Peter Mitchell.

9 ANS: This question has given lots of false statements and I will go through each of them and in the process explain briefly.
a) The cause of the ion gradient is not only because of selective permeability of ions but several factors like the fact that the inner mitochondrial membrane is composed of multi-protein enzyme complexes (respirasome) that pump proton from the matrix to the inter-membrane space. But there indeed lies a fact that the inner membrane is impermeable to most ions which is important since it is responsible for creating the pmf. So this may be partly true.

b) False - requires the malate-aspartate shuttle for the transport process.

C) True - Indeed ATP-ADP translocase has a single nucleotide-binding site.

d) True- porins indeed function in that way.

e) True - cristae can be found in the inner mitochondria.

10 ANS: To know the correct order of the events, try to match my answer with the drawing in the question. The ATP synthase β sub-unit can assume 3 active conformations, those are loose (L), Tight (T) & Open (O). The stalk or the central part (γ sub-unit) can rotate owing to the PMF and in turn, can shift the associated conformations accordingly. So think the ATP synthesis machine in its 2 conformations (T & L) allows ATP, ADP & P_i to bind while in the O releases ATP. Now it's a circular process so when ADP and P_i are loosely bound to the L site, the T site has ATP bound to it tightly and in the O site is vacant. Now it starts moving so ADP and P_i go to the T site and it becomes readily converted to ATP and the ATP previously on the T site is released from the O site and the L site is recruiting ADP and P_i and the process is repeated.

D is the option that matches this process.

11 ANS:

NADH NAD+ H+ COMPLEX1 + Q → COMPLEX 3 → Cyt + Compler 4 + H2O +502 + 2H+

12 ANS:

FADH, FAP Q + COMPLEX 3 + Cyt C + Complex 4 + H2O + 02 + 2H+

NOTE: If you have any queries feel free to refer to the comment section & I will get back to you.