[Campbell Biology P.201] Figures 8.11a and 8.11b illustrate two different ways ATP drives ce... | Practice Question

Figures 8.11a and 8.11b illustrate two different ways ATP drives cellular work: transport work and mechanical work. What is the key distinction in how ATP directly powers these two types of work according to the figures?

  • A: In transport work, ATP phosphorylates the protein directly, while in mechanical work, ATP binds noncovalently and is then hydrolyzed.
  • B: Transport work always involves an inorganic phosphate, but mechanical work does not.
  • C: Mechanical work requires ATP to be completely consumed, while transport work only requires partial hydrolysis.
  • D: Transport work changes the protein's shape, but mechanical work moves the protein along a track without shape change.

Explanation

According to Figure 8.11a, transport work involves ATP phosphorylating the transport protein directly, causing a shape change. In contrast, Figure 8.11b shows that for mechanical work, ATP binds noncovalently to the motor protein and is then hydrolyzed, leading to a shape change that enables movement along the cytoskeletal track.