Biochemistry : ATP Synthase

Study concepts, example questions & explanations for Biochemistry

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Example Questions

Example Question #1 : Atp Synthase

Which of the following is false about the structure and function of ATP synthase?

Possible Answers:

It is a membrane-bound protein.

It synthesizes over 100 ATP molecules per second.

The rotor has 10 to 14 subunits.

There are six subunits in its ring.

At least 10 protons pass through ATP synthase in order to make a molecule of ATP.

Correct answer:

At least 10 protons pass through ATP synthase in order to make a molecule of ATP.

Explanation:

ATP synthase can indeed produce more than 100 ATP molecules per second, and in the process, it only requires a few -- three or four -- protons, per ATP. These protons pass down a gradient through the membrane. Hence, the protein is membrane-bound. The protons cause the rotor of 10-14 subunits to spin. The protein's head itself has six subunits, three of which have ADP binding and phosphate binding sites.

Example Question #2 : Atp Synthase

What is the basic mechanism by which ATP synthase generates ATP in the mitochondria?

Possible Answers:

The formation of ATP is energetically favorable and does not require a synthase to be formed

The high energy electrons from oxidative phosphorylation react with the separate components of ATP and drive them together by using ATP synthase

ATP synthase uses energy from G-protein complexes to phosphorylate ADP to ATP

The proton gradient set up by the electron transport chain causes mechanical rotation of ATP synthase, and this energy is used to form ATP

ATP synthase uses an electron gradient set up by oxidative phosphorylation to drive ATP synthesis

Correct answer:

The proton gradient set up by the electron transport chain causes mechanical rotation of ATP synthase, and this energy is used to form ATP

Explanation:

The electron transport chain moves high energy electrons through its complexes in order to create a proton gradient across the mitochondrial inner membrane.  The ATP synthase then uses this gradient to pass hydrogen atoms through it.  Because this is a favorable movement, it can be coupled to unfavorable processes such as conversion of ADP to ATP.  

Example Question #3 : Atp Synthase

ATP synthase catalyzes which of the following reactions?

Possible Answers:

Correct answer:

Explanation:

ATP synthase catalyzes the reaction that shows ADP and the phosphate group forming ATP.  The hydrogen in the reactant side is the one involved in the proton gradient, and water is a byproduct of the reaction.

Example Question #4 : Atp Synthase

Which of the following part(s) of ATP synthase is involved in catalysis?

Possible Answers:

Alpha subunit

Gamma subunit 

Alpha, beta, and gamma subunits

Beta subunit

Alpha and beta subunits

Correct answer:

Beta subunit

Explanation:

ATP synthase is located in the inner mitochondrial membrane. It has an F0 portion within the membrane and an F1 portion in the matrix. The F1 portion has a hexameric ring structure and is responsible for the creation of ATP from mechanical energy. The alpha, beta, and gamma subunits are all parts of the F1 portion of ATP synthase, however it is only the alpha and beta subunits that form the ring. Further, the beta subunit is the part of the ring that is considered to be catalytic.

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