Chapter 14 Set 2

Approximately how many molecules of ATP can be produced in mitochondria from the complete oxidation of a single glucose molecule?

-30 -Oxidative phosphorylation is much more efficient than glycolysis when it comes to producing ATP.

Which activated carrier contains a high-energy bond whose hydrolysis releases a large amount of free energy?

-ATP

What happens when ATP synthase operates "in reverse" and pumps H+ across a membrane against its electrochemical proton gradient?

-ATP is hydrolyzed to form ADP and Pi -ATP synthase is a reversible device that couples the movement of protons with the synthesis (and hydrolysis) of ATP.

Suppose the shaft of ATP synthase that is attached to the rotor were truncated (shortened) such that it no longer extended into the F1 ATPase head. What would be the consequence of this mutation?

-ATP would not be produced because the conformation of the F1 ATPase head would not be changed.

Which statement regarding the ratio of ATP and ADP concentrations in the cell cytosol is accurate?

-Cells keep the concentration of ATP in the cytosol about 10 times higher than that of ADP. -

Which is true about electrons as they move through the electron-transport chain?

-Electrons start out at very high energy and lose energy at each transfer step along the electron-transport chain -Remember, the movement of electrons along the electron-transport chain releases energy that is used to pump protons across the membrane.

Ubiquinone has a redox potential of +30 mV, while cytochrome c has a redox potential of +230 mV. During electron transport, which is true?

-Electrons will flow from ubiquinone to cytochrome c. -Electrons move spontaneously toward molecules with a greater electron affinity

During oxidative phosphorylation, why does a single molecule of NADH result in the production of more ATP molecules than a single molecule of FADH2?

-FADH2 and NADH feed their electrons to different carriers in the electron-transport chain. -Remember that electrons release energy as they are passed along the electron-transport chain.

In an animal cell, where are the proteins of the electron-transport chain located?

-Inner mitochondrial membrane

Which is true of ATP synthase?

-It can either produce or break down ATP depending on the magnitude of the electrochemical proton gradient. -ATP synthase can reverse direction, depending on the needs of the cell.

Most of the energy for the synthesis of ATP comes from which molecule?

-NADH produced by the citric acid cycle

Some types of bacteria can survive under both aerobic and anaerobic conditions. Regardless of whether oxygen is present, these cells maintain a proton gradient across the plasma membrane to drive ATP synthesis and the import of nutrients. Under aerobic conditions, an H+ gradient across the plasma membrane is produced by the transfer of electrons along the respiratory chain. When oxygen is present, what would be expected to occur in the plasma membrane of these bacteria?

-Protons flow into the bacterial cell through ATP synthase, generating ATP.

Diseases that disrupt the function of mitochondria are particularly harmful to muscle and nerve cells for what reason?

-These cells need large amounts of ATP to function normally. -The consequences of such disruption are most apparent in the cells that depend on mitochondria most heavily.

Why can electron carriers move a proton from one side of a membrane to the other

-They can accept an electron (along with an H+ from water) on one side of the membrane and then release the H+ on the other side of the membrane as they pass the electron to the next carrier. -Not all electron carriers are capable of pumping protons, and those that do are generally large, multisubunit protein complexes.

What is true of the organelles that produce ATP in eukaryotic animal cells

-They evolved from bacteria engulfed by ancestral cells billions of years ago.

Which of the following drives the production of ATP from ADP and Pi by ATP synthase?

-a proton (H+) gradient -Production of ATP by ATP synthase is powered by chemiosmotic coupling.

ATP synthase is a large molecular machine that converts the energy in an electrochemical gradient into the bond energy stored in ATP. Which of the following events are required for the synthesis of ATP?

-conformational changes of the F1 ATPase -movement of protons down their gradient through ATP synthase -rotation of the rotor in the membrane

It is energetically favorable for protons to flow in which direction?

-from the intermembrane space to the mitochondrial matrix -Recall that the pH of the mitochondrial matrix is higher than that of the intermembrane space

The electron-transport chain pumps protons in which direction?

-from the matrix to the intermembrane space -The pH of the matrix is higher than that of the intermembrane space. Is a higher pH associated with more H+ or more OH¯?

Which part of the mitochondrion contains the proteins that carry out oxidative phosphorylation?

-inner mitochondrial matrix -This highly specialized structure is folded into cristae to increase its surface area.

Under which of the conditions pictured will ATP synthase produce ATP?

-more protons in inter membrane space -The enzymes of the electron-transport chain pump protons out of the mitochondrial matrix and into the intermembrane space.

Which part of the mitochondrion contains porins?

-outer membrane

In mitochondria, what is the final electron acceptor in the electron-transport chain?

-oxygen (O2)

When protons move down their electrochemical gradient into the mitochondrial matrix, what do they do?

-produce ATP -Protons flowing across the inner mitochondrial membrane into the matrix pass through an enzyme complex that converts this kinetic energy into chemical-bond energy.

In the electron-transport chain, as electrons move along a series of carriers, they release energy that is used to do what?

-pump protons across a membrane -The energy released during the movement of electrons along the electron-transport chain is stored in a form that can subsequently be tapped to generate ATP.

The movement of electrons through the electron-transport chain in mitochondria does which of the following?

-pumps protons out of the mitochondrial matrix

Which part of the mitochondrion contains the enzymes needed to complete the oxidation of food-derived molecules?

-the matrix -The oxidation of food-derived molecules, which takes place inside mitochondria, does not require a membrane.

For what reason is cytochrome c oxidase able to pump protons across the inner mitochondrial membrane?

Electron transport drives a conformational change in the protein complex.

The electron-transport chain in mitochondria accepts high-energy electrons directly from which molecule?

NADH