BIOL 310 - Molecular Cell Biology: ATP Synthesis

From Lodish Chapter 12.4-12.5

How many ATP are generated from one glucose molecule? How many of these are from ATP synthase?

38, 36 from ATP synthase

What is the electron transport chain?

The system by which four complexes transport protons against the gradient by way of energy from electrons

Which complexes directly pump protons?

I, III, IV

What does Complex II do in the electron transport chain?

Promotes proton pumping in complexes III and IV

Where does Complex 1 get it’s electrons?

NADH

How are electrons transported through complex 1?

Moving down a line of redox centers

Why do electrons move between redox centers?

The redox centers are organized with lowest affinity at the top and highest affinity at the bottom, so electrons will always move own to the next highest affinity

How does electron transport through redox centers allow complex I to pump protons?

Each jump between redox centers releases a little bit of energy which is harnessed to power proton pumping

Where do electrons go after the last redox center in complex I?

Picked up by coenzyme Q (2 at a time) and shuttled to complex III

What is the destination of protons pumped by the electron transport chain?

Intermembrane space

Where are protons high in concentration? Where are they low in concentration?

High: intermembrane space

Low: Matrix

What are the two main units of ATP synthase? What parts of the molecule do they make up?

F1, Upper bubbly ring and stem

F0, left holder thingy and rotating drum at the bottom

What subunits compose the F1 part of ATP synthase? Where are they found?

alpha, beta - 3 each, compose big ring on matrix side

Gamma - stem

Delta - connects matrix ring to F0

Epsilon - little nub on stem

What subunits compose the F0 part of ATP synthase? Where are they found?

a - borders c-ring, contains proton half channels

b - 2 of these - long sticks that connect transmembrane part to matrix-side part

c - can be anywhere from 8 to 15 - form a ring in the membrane

What is the “-ase” name for the F1 part of ATP synthase?

F1 ATPase

What side of the membrane does a proton enter ATP synthase from? What is it’s interaction with ATP synthase?

Enters from intermembrane (exoplasmic) side.

Proton enters half-channel 1, is picked up by Asp61, begins to turn with c-ring

How does a proton leave ATP synthase? What side of the membrane does it exit to?

The proton reaches half-channel 2 and interaction with Arg210 takes it off of the c-ring and releases it onto the matrix (cytosolic) side of the membrane.

How many protons are needed to produce 1 ATP?

about 2

How much of a rotation of the gamma subunit is necessary to produce 1 ATP?

120 degree

What are the three possible states for a beta subunit in ATP synthase? What happens in each?

O (open) - ADP + Pi can enter or ATP can leave

L (loose) - ADP + Pi kind of just sits there

T (tight) - ADP + Pi react to form ATP

What kind of structure does ATP synthase for in the cell?

F0F1 dimers, two synthase molecules side by side