BIOC 2580 Lecture Notes - Lecture 18: Atp Synthase, Chemiosmosis, Protonation

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champagneferret889

24 Jun 2016

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Boyer suggested that the atp synthase active site cycles between a form that tightly binds atp and a form that releases atp. The active site, in a cyclic fashion is formed, torn apart and then re-formed to allow the continued synthesis of atp. Structural basis for rotational catalysis: each subunit of f1 can assume 3 different conformations. The subunit interacts asymmetrically with the 3 3 complex causing the three subunits to have different conformations, each associated with differences in their adp/atp binding site. At a given time one subunit is in the loose conformation, another in the tight conformation and the third in the open conformation. Each subunit is able to cycle between these 3 forms. During catalysis, the subunit rotates in the centre of the 3 3 complex. With each 1200 turn of the subunit a different face comes into contact with each subunit, rotating them between the three diff conformations.

Related Questions

1.Bacteriorhodopsin is a protein that has 7 alpha helices embedded in the cell membrane. As such, how many start-transfer and stop-transfer sequences would it need?

7 start transfer sequences, 6 stop transfer sequences

7 of each, in alternating fashion

4 start transfer sequences and 3 stop transfer sequences

7 start transfer sequences

2. The role of GTP hydrolysis by the Signal Recognition Particle during cotranslational translocation to the ER is

to release the SRP after docking to the translocon so translation can resume.

to open the gate/pore of the translocon into the ER.

to arrest translation so that synthesis does not finish before the peptide is delivered to the translocon.

to allow binding to the ribosome.

3. The cisternal maturation model is just one model that describes how objects might move through the Golgi. Some of the statements below describing the cisternal maturation model are correct and some are incorrect. Select all the incorrect descriptions.

There's no need for retrograde movement

Vesicles bud off from the Trans Golgi Network toward the plasma membrane

Vesicular tubules move materials from the cis to medial Golgi networks.

There are no vesicles moving in the anterograde direction

4. Select all statements that are correct concerning electron transport and ATP synthesis during photosynthesis in chloroplasts.

Each photosystem (I and II) pump protons.

Protons are pumped into the lumen of the thylakoid.

The bulb of the synthase projects into the stroma

Photosystem I is reduced directly by Photosystem II

5. Select all that are true about ATP synthesis with an F_oF₁ synthase complex.

Each ADP+Pi is transferred from one beta subunit in Open conformation to a second beta subunit in Loose conformation and finally to the 3rd beta subunit in the T conformation

As the gamma subunit rotates to each beta subunit, it forces them to the open state.

As the gamma subunit rotates to a particular beta subunit, the unit before it changes conformation to Tight and the one ahead of it changes to Loose

As the gamma subunit rotates to a particular beta subunit, the unit before it changes conformation to Loose and the one ahead of it changes to Tight

All 3 beta subunits are always in a different conformation (open, loose, or tight)

6. The number of ATPs per NADH generated by the electron transport system is higher than the number generated per FADH2 because __________.

		electrons from FADH₂ are not oxidized all the way to water
		NADH is converted to NAD⁺, which increases the charge gradient for ATP synthesis
		FADH₂ has a lower (less negative) redox potential than NADH does
		FADH₂ has a higher (more negative) redox potential than NADH does

BIOC 2580 Lecture Notes - Lecture 18: Atp Synthase, Chemiosmosis, Protonation

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