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BIO 355- CELL BIO > Ch. 14 > Flashcards

Ch. 14 Flashcards

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1
Q

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

A

A proton gradient

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2
Q

Which of the following processes involves a membrane?

A

Oxidative phosphorylation

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3
Q

What is the main chemical energy currency in cells?

A

ATP

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4
Q

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

A

pump protons across a membrane.

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5
Q

The organelles that produce ATP in eukaryotic cells:

A

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

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6
Q

.Which of the following organisms do not have mitochondria in their cells?

A

Bacteria

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7
Q

In mitochondria, with the complete breakdown of glucose, about how many molecules of ATP can be produced for each molecule of glucose oxidized?

A

30

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8
Q

Mitochondria can change their location, shape, and number in the cell to suit the needs of a cell.

A

true

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9
Q

Which of the following is NOT true of mitochondria?

A

They are replaced by chloroplasts in plants.

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10
Q

The outer membrane of a mitochondrion is permeable to all small molecules, including small proteins.

A

True

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11
Q

.In a eukaryotic cell, where are most of the proteins for the electron transport chain located?

A

In the mitochondrial inner membrane

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12
Q

Which of the following is not a direct source of fuel for mitochondria?

A

Glucose

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13
Q

The electron transport chain accepts high-energy electrons from:

A

NADH and FADH2

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14
Q

Which of the following statements is true about the electron transport chain?

A

Electrons start out at very high energy and lose energy at each transfer step.

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15
Q

The movement of electrons through the electron transport chain:

A

pumps protons across the inner mitochondrial membrane.

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16
Q

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

A

Molecular oxygen (O2)

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17
Q

The electron transport chain pumps protons:

A

from the matrix to the intermembrane space.

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18
Q

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

A

From the intermembrane space to the mitochondrial matrix

19
Q

When protons move down their electrochemical gradient into the mitochondrial matrix, they:

A

produce ATP.

20
Q

ATP synthase:

A

can either produce or break down ATP depending on the magnitude of the electrochemical proton gradient.

21
Q

What occurs when ATP synthase pumps H+ across a membrane against the electrochemical proton gradient?

A

ATP synthase cleaves ATP to form ADP and Pi

22
Q

The proton gradient can drive the active transport of metabolites into and out of the mitochondrion.

A

True

23
Q

What is the ratio of ATP and ADP concentrations in the cytosol of a cell?

A

High ATP/ADP ratio

24
Q

Why does a single molecule of NADH result in the production of more ATP molecules than a single molecule of FADH2 via oxidative phosphorylation?

A

FADH2 feeds its electrons into the electron transport chain further along the chain.

25
Q

Cellular respiration:

A

is more efficient at generating energy than a gasoline-powered engine.

26
Q

.In the electron transport chain, what provides the main reservoir for protons that are pumped across the membrane?

A

H2O

27
Q

Which of the following statements is NOT true of electron transfer in the electron transport chain?

A

When an electron carrier accepts an electron, it becomes oxidized.

28
Q

When the difference in redox potential between two pairs of molecules is highly positive, then the transfer of the electrons is:

A

highly favorable.

29
Q

As electrons move through the electron transport chain, they are passed from:

A

a carrier molecule of lower electron affinity to a carrier molecule of higher electron affinity.

30
Q

NADH has a weak affinity for electrons and a negative redox potential.

A

True

31
Q

NADH has a strong tendency to:

A

donate electrons.

32
Q

.Ubiquinone has a redox potential of +30 mV, while cytochrome c has a redox potential of +230 mV. In the electron transport chain, electrons flow from:

A

Ubiquinone to cytochrome c.

33
Q

When O2 accepts electrons in the electron transport chain, O2 becomes _______.

A

reduced

34
Q

Photosynthesis allows plant to capture energy from sunlight to produce:

A

SUGARS

35
Q

In chloroplasts the pigment chlorophyll donates electrons to an electron transport chain in the thylakoid membrane.

A

True

36
Q

.In the electron transport chain in chloroplasts, which molecule serves as the final electron acceptor?

A

NADP+

37
Q

What provides the fuel to convert CO2 into sugars in chloroplasts?

A

ATP and NADPH generated in the photosynthetic light reactions

38
Q

The first living cells on Earth–both prokaryotes and primitive eukaryotes–most likely generated ATP by what process?

A

Fermentation

39
Q

What electron acceptor allows an organism to completely break down organic molecules into CO2 and H2O and thereby release a large amount of energy that can be harnessed by the cell to do work?

A

O2

40
Q

The storage of energy in a proton gradient derived from electron transport is a recent evolutionary development.

A

False

41
Q

Nitrogen fixation:

A

Reduces N2 to ammonia (NH3).

42
Q

What is the difference between photosystems I and II?

A

Photosystem II donates electrons to an electron-transport chain. These electrons pass through a proton pump, which uses their movement to generate an electrochemical proton gradient that ultimately produces ATP. The electrons that leave photosystem II are replaced by electrons that are stripped from water.

Photosystem I donates its electrons to a mobile electron carrier that, in turn, hands them to an enzyme that uses the electrons to produce NADPH. The electrons that leave photosystem I are replaced by electrons that were donated by photosystem II.

43
Q

Why is O2 / H2O is an excellent electron acceptor for the end of the respiratory chain, while NADH/NAD+ is an excellent electron donor to the respiratory transport chain?

A

The tendency of oxidation-reduction reactions, or redox reactions, to proceed spontaneously depends on the free-energy change for the electron transfer, which in turn depends on the relative affinities of the two molecules for electrons. Electrons pass spontaneously from molecules that have a relatively low affinity for their outer shell electrons to molecules that have a high affinity for electrons.

Electrons will move spontaneously from a redox pair with a low redox potential (or low affinity for electrons) such as NADH/NAD+, to a redox pair with a high redox potential (or high affinity for electrons) such as O2 / H2O. Thus, NADH is an excellent molecule to donate electrons to the respiratory chain, while O2 is well suited to act as an electron acceptor at the end of the pathway.

BIO 355- CELL BIO (11 decks)

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