Question

ATP synthase is the poster child example for a molecular machine.

A. What are the two components of ATP synthase and their respective functions?

B. What is the energy barrier for ATP synthase in terms of providing the cell with ATP?

C. List the location(s) of ATP synthase in (i) bacterial, (ii) archaeal, (iii) plant, (iv) and animal cells?

Answer 1

Ans a) The ATP synthase is an enzyme which helps in the production of ATP and hence helps in providing the cells energy molecule. It is an important enzyme required for cellular respiration and it produces ATP which is used by the cells for producing energy. The ATP synthase enzyme has two parts and each of it has its own function.

Fo base– This is the part of the membrane which functions as a motor and is embedded within the plasma membrane. This is the part which enables flow of H+ ions across membrane and this acts as channel which enables free movement of protons across it.

F1 head – This is the part of the ATP synthase which faces the matrix and is hydrophilic in nature. This is the part which helps in hydrolysis of ATP. It consists of 5 subunits which are 3 subunits each of alpha and beta, gamma stalk, epsilon and delta. The alpha and beta subunits binds and forms 6 binding sites out of which three bind to ADP and hence are catalytically inactive.

Ans b) The energy barrier for ATP synthase for providing the cells with ATP is through the movement of the H+ ions across the mitochondrial membrane. Hence this barrier and the movement of H+ ions help in the formation of the ATP. The ATP synthase generally help with the process of ATP synthesis through the use of existing ion gradient.

Ans c)

1. Bacterial – The ATP synthase is located within the bacteria in cell membrane and the F1 portion of the enzyme which is hydrophilic in nature sticks into the cytoplasm.
2. Archael – In the archael cell also, it is located across the plasma membrane and it is the F1 part of the ATP synthase enzyme which is embedded within the membrane.
3. Plants – The ATP synthase is present within the thylakoid membrane in the chloroplast and within the thylakoids, the H+ ions travel through ATP synthase from thylakoid space towards the stromal side.
4. Animal cells – Within the animals cells, the ATP synthase is located within the mitochondrial membrane of the animal cells.