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BIOL150 > Chapter 7 > Flashcards

Chapter 7 Flashcards

1
Q

List and briefly describe the four metabolic pathways that are needed to break down glucose to CO2 and H2O

A

Glycolysis: Breakdown of glucose into 2 pyruvates; can occur with or without oxygen; three phases (energy investment, cleavage, energy liberation)

Breakdown of Pyruvate: pyruvate is transported into the mitochondrial matrix (eukaryotes); molecule of CO2 is removed from each pyruvate; remaining acetyl group attached to CoA to make acetyl CoA; yields 1 NADH for each pyruvate

Citric Acid Cycle: metabolic cycle; series of organic molecules regenerated in each cycle; acetyl is removed from acetyl CoA and attached to oxaloacetate to form citrate; oxaloacetate is regenerated to start the cycle again; energy initially present in glucose is transferred to electron carriers; ATP is generated via substrate level phosphorylation; series of steps released 2 CO2, 1 ATP, 3 NADH, and 1 FADH2

Oxidative Phosphorylation: Passes high energy electrons from 10 NADH and 2FADH2 down an energy gradient across inner mitochondrial membrane (ETC); series of redox reactions involving several proteins and enzymes embedded within inner mitochondrial membrane; Energy from electron carriers used to pump H+ ions into intermembrane space and establish H+ gradient; Oxygen is a terminal electron acceptor in ETC; Energy is from H+ gradient used to synthesize ATP through oxidative phosphorylation

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2
Q

Identify the inputs and outputs of each of the four metabolic pathways of cellular respiration and where in the cell they occur

A

Glycolysis: glucose, 2NAD+, 2ATP, and 2P are the inputs; 2 pyruvates, 4 ATP (2 net total), 2 NADH

Breakdown of Pyruvate: 2 pyruvates, 2 CoA, 2 NAD+ are inputs; 2 Acetyl-CoA, 2 NADH, and 2 CO2 are outputs

CAC: 2 Acetyl-CoA, 6 NAD+, 2 FAD, 2 ADP+P are the inputs; 4 CO2, 6 NADH, 2 FADH2, 2 ATP (or GTP) are the outputs

Oxidative Phosphorylation: ADP, 10 NADH, 2 FADH2, and O2 are the inputs; 32 ATP, NAD+, FAD+, and H2O are the outputs

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3
Q

Review the two ways ATP is made

A

Substrate-level phosphorylation: Involves an enzyme that transfers a phosphate group from a substrate to ADP

Oxidative phosphorylation: occurs in the mitochondria and uses energy from a proton gradient to drive ATP synthesis

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4
Q

Review oxidation reduction reactions

A

Oxidation reactions = one substance loses electrons
Reduction reactions = one substance gains electrons
These always occur together, so they are called redox reactions

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5
Q

Outline the three phases of glycolysis and identify the net products

A

Energy Investment: 2 ATP hydrolyzed to create fructose-1,6 bisphosphate; phosphates added to glucose to prevent it from leaving the cell and to destabilize the molecule

Cleavage: 6 carbon molecules broken down into 3 carbon molecules of glyceraldehyde-3-phosphate

Energy Liberation: 2 glyceraldehyde-3-phosphate molecules broken down broken down into 2 pyruvate molecules

produces 2 NADH and 4 ATP (net yield=2)
ATP produced via substrate level phosphorylation

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6
Q

Describe the products of pyruvate oxidation

A

pyruvate is converted to acetyl-CoA (removal of a carboxyl group from pyruvate, followed by oxidation and attachment to coenzyme A). One molecule of NADH is produced and one molecule of CO2 is released in the process

Acetyl-CoA enters the citric acid cycle, where it acts as a fuel for the next stage of cellular respiration

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7
Q

Explain the concept of a metabolic cycle

A

A series of chemical reactions in a cell that build and breakdown molecules for cellular processes. Anabolic and Catabolic reactions
(redox reactions - oxidation and reduction)

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8
Q

Describe the net products of the citric acid cycle

A

6 NADH
2 FADH2
4 CO2
2 ATP

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9
Q

Discuss the events of oxidative phosphorylation

A

Oxidative Phosphorylation: Passes high energy electrons from 10 NADH and 2FADH2 down an energy gradient across inner mitochondrial membrane (ETC); series of redox reactions involving several proteins and enzymes embedded within inner mitochondrial membrane; Energy from electron carriers used to pump H+ ions into intermembrane space and establish H+ gradient; Oxygen is a terminal electron acceptor in ETC; Energy is from H+ gradient used to synthesize ATP through oxidative phosphorylation

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10
Q

Describe how the electron transport chain produces an H+ electrochemical gradient

A

As an electron passes through the ETC, the energy it releases is used to pump protons (H+ ions) out of the mitochondrial matrix or stroma of the chloroplast forming an electrochemical gradient. The free energy released when the redox reactions of an ETC are coupled to the active transport of protons across a membrane creates a chemical gradient of H+ ions as well as a pH gradient. When the H+ ions flow back down their gradient, they pass through an enzyme called ATP synthase, driving the synthesis of ATP

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11
Q

Explain how ATP synthase utilizes the H+ electrochemical gradient to synthesize ATP

A

ATP synthase is a complex protein that acts as a tiny generator, turning by the force of the H+ diffusing through the enzyme, down their electrochemical gradient from where there are many mutually repelling H+ to where there are fewer H+
The enzymatic activity of ATP synthase synthesizes ATP from ADP

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12
Q

Glycolysis: Glucose

A

The main reactant in glycolysis that produces 2 pyruvate molecules

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13
Q

Glycolysis: Isomer

A

In the second step of glycolysis, an isomerase converts glucose-6-phoshate into one of its isomers, fructose-6-phosphate. An isomerase is an enzyme that catalyzes the conversion of a molecule into one of its isomers. This change from phosphoglucose to phosphofructose allows the eventual split of the sugar into two three-carbon molecules

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14
Q

Glycolysis: Glyceraldehyde

A

Glyceraldehyde-3-phosphate gets oxidized and the high-energy electrons are extracted

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15
Q

Glycolysis: Pyruvate

A

the output glycolysis and input for the breakdown of pyruvate

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16
Q

Glycolysis: Kinase

A

The most important enzyme for regulation of glycolysis. It speeds up or slows down glycolysis in response to the energy needs of the cell

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17
Q

Glycolysis: Isomerase

A

Isomerase converts glucose-6-phosphate into one of its isomers, fructose-6-phosphate

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18
Q

Glycolysis: Dehydrogenase

A

This type of enzyme catalyzes the sixth step of glycolysis and breaks down glucose for energy and carbon molecules. Another dehydrogenase enzyme converts pyruvate into lactic acid, using a unit of NADH and releasing hydrogen to produce NAD+

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19
Q

Glycolysis: Cleavage

A

When 6 carbon molecules break into 2 3 carbon molecules of glyceraldehyde-3-phosphate

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20
Q

Glycolysis: Reduced

A

reduction refers to the gain of hydrogen by coenzymes FAD and NAD

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21
Q

Glycolysis: Oxidized

A

The overall process of glycolysis is an oxidation reaction (glucose loses electrons and becomes more oxidized

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22
Q

Glycolysis: ATP and Phosphate group

A

ATP: used to phosphorylate glucose and other intermediates, making them more reactive and preventing them from leaving the cell
Phosphate group: involved in the first step of the process, where glucose is phosphorylated by the enzyme hexokinase. A phosphate group is transferred from ATP to glucose, forming glucose-6-phosphate or G6P

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23
Q

Glycolysis: NAD+, NADH

A

NAD+: a coenzyme that accepts electrons from G3P; is reduced and forms NADH and H+

NADH: the reduced form of NAD+

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24
Q

Glycolysis: Preparatory, Cleavage

A

Preparatory: energy in glucose cannot be readily released unless energy from ATP is added first (2 ATP are added to the reaction, producing a glucose molecule with two phosphate groups. The phosphate groups make glucose less stable and ready for chemical breakdown)
Cleavage: 6 carbon molecules broken into two 3 carbon molecules of G3P

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25
Q

Glycolysis: Payoff Phase

A

The second phase of glycolysis where the energy invested in the first phase is repaid with interest. Two molecules of G3P are oxidized by transferring electrons to NAD+, forming NADH. The energy released from this redox reaction is used to attach phosphate groups to oxidized substrates, making products of high potential energy. These phosphate groups are then transferred to ADP, producing four molecules of ATP by substrate-level phosphorylation. The net energy yield from this phase is two NADH and two ATP per glucose molecule

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26
Q

Glycolysis: Cytosol

A

Glycolysis happens in the cytosol, while the rest of the steps occur in the mitochondrial matrix

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27
Q

Glycolysis: Substrate-level phosphorylation

A

The purpose of this is to produce ATP by transferring a phosphate group from ma phosphorylated substrate to ADP

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28
Q

Pyruvate Oxidation: Mitochondrion layers

A

These layers are responsible for importing pyruvate from the cytosol to the mitochondrial matrix, where it’s oxidatively phosphorylated to produce ATP.

29
Q

Pyruvate Oxidation: Acetyl

A

Pyruvate is converted to acetyl CoA in a process that involves the loss of one carbon atom with the release of CO2

30
Q

Pyruvate Oxidation: CoenzymeA (CoA)

A

plays a role in the oxidation of pyruvate. The reaction oxidizes pyruvate, leads to a loss of one carbon via decarboxylation, and creates a new molecule called acetyl-CoA

31
Q

Pyruvate Oxidation: AcetylCoA

A

created from the oxidation of pyruvate and is used to deliver the acetyl group derived from pyruvate to the next stage of the pathway in glucose catabolism

32
Q

Pyruvate Oxidation: NAD+, NADH

A

NAD+ becomes NADH in pyruvate oxidation by picking up the electrons lost when pyruvate is converted into acetyl CoA
The NADH formed carries high-energy electrons that can be used to generate ATP

33
Q

Pyruvate Oxidation: Pyruvate dehydrogenase

A

This controls the amount of acetyl-CoA that enters the citric acid cycle (regulatory enzyme)

34
Q

Pyruvate Oxidation: CO2

A

A waste product that’s diffused or transported out of the cell

35
Q

Citric Acid Cycle: AcetylCoA

A

Acetyl-CoA conveys the carbon atoms within the acetyl group to the citric acid cycle to be oxidized for energy production

36
Q

Citric Acid Cycle: Oxaloacetate

A

an intermediate of the CAC
reacts with acetyl-CoA to form citrate

37
Q

Citric Acid Cycle: NAD+, NADH

A

NAD+: a coenzyme that acts as an electron acceptor in the process of glycolysis and the CAC. It’s reduced
NADH: the purpose of making NADH and FADH2 in the CAC is to transfer the high energy electrons from the oxidation of acetyl-CoA to the electron transport chain

38
Q

Citric Acid Cycle: FAD, FADH

A

FAD: electrons and hydrogen atoms from the oxidation of acetyl CoA combine with FAD molecules to form FADH2

39
Q

Citric Acid Cycle: Amphibolic

A

serves both anabolic and catabolic processes
breaks down acetyl CoA to yield carbon dioxide and energy along with provides intermediates for the synthesis of amino acids and other biomolecules

40
Q

Citric Acid Cycle: Substrate-level phosphorylation

A

When succinate is formed, the reaction releases sufficient energy to form ATP by substrate-level phosphorylation

41
Q

Electron Transport Chain: NADH, NAD+

A

NAD+ is reduced to NADH, which carries the electrons gained from the breakdown of glucose and donates them to the chain of enzymes in mitochondria that are involved in producing ATP. NADH is oxidized back to NAD+ in this process. NADH acts as an electron transporter as it flows through the inner membrane space

42
Q

Electron Transport Chain: FADH2, FAD

A

FAD can accept either one or two electrons at a time, and its reduced form, FADH2 can donate either one or two electrons at a time. FADH2 bypasses the first complex of the ETC and delivers electrons directly to the chain, resulting in fewer ATP molecules being made from the FADH2 electrons

43
Q

Electron Transport Chain: Complex 1, 2, 3

A

Complex 1 [NADH dehydrogenase]: oxidation of NADH; energy from e- is used to pump H+ across inner mitochondrial membrane

Complex 2 [Succinate Reductase]: Oxidation of FADH2 to supply additional electron to the chain

Complex 3 [cytochrome b-c1]: cytochrome c transfer electrons between the different complexes (energy from e- used to pump H+ across inner mitochondrial membrane

Complex 4 [cytochrome oxidase]: final terminal electron acceptor (such as oxygen); O2 is reduced to H2O

44
Q

Electron Transport Chain: Proton pump

A

responsible for pumping protons across inner mitochondrial membrane from the matrix to the intermembrane space. This creates an electrochemical gradient consisting of a proton gradient and a membrane potential

45
Q

Electron Transport Chain: ATP synthase

A

complex V of the ETC
Catalyzes the synthesis of ATP from ADP and Pi by oxidative phosphorylation

46
Q

Electron Transport Chain: Electrochemical Gradient

A

As electrons are passed down the chain, they move from higher to lower energy levels, releasing energy. This energy is used to pump hydrogen ions into the mitochondrial intermembrane space, creating an electrochemical gradient
essential for ATP production

47
Q

Electron Transport Chain: CoQ

A

Coenzyme Q carries and donates electrons

48
Q

Electron Transport Chain: Cytochrome c

A

electron transfer protein
shuttles electrons between complexes 3 and 4 of the ETC

49
Q

Electron Transport Chain: Cristae

A

key components of the ETC are here
the folding or wrinkling of the cristae on the inner mitochondrial membrane creates a large surface area inside the mitochondria. This increased surface area allows for more space where the ETC can occur

50
Q

Electron Transport Chain: Oxidative Phosphorylation

A

ETC is where oxidative phosphorylation occurs

51
Q

Electron Transport Chain: Terminal Electron Acceptor

A

Oxygen

52
Q

Glucose + 6O2 -> 6CO2 + 6H20 + energy (ATP) is the overall reaction for cellular respiration. Give a general explanation for what is occurring

A

Glucose gets broken into carbon dioxide and water
H and electrons go from glucose to Oxygen which forms H2O (and ATP)

53
Q

Where/when/how is most of the ATP produced?

A

Oxidative phosphorylation; mitochondrial matrix
Energy is liberated and used to pump protons out of the matrix as electrons flow down the chain, resulting in a gradient. This energy is used to drive ATP synthase and produce ATP from ADP and a phosphate group. Each molecule of glucose oxidized can create around 32 ATP

54
Q

Why is ATP needed for the first stages of glycolysis?

A

One ATP is used to phosphorylate glucose, producing glucose-6-phosphate
another ATP is used to phosphorylate fructose-6-phosphate, producing fructose-1,6-bisphosphate

55
Q

What is oxidized and what is reduced in cellular respiration

A

glucose is oxidized to carbon dioxide
oxygen is reduced to water

56
Q

Discuss the 3 main parts of glycolysis and the reactions that occur in each part.

A

Energy investment: 2 ATP hydrolyzed to create fructose-1,6-bisphophate; phosphates added to glucose to prevent it form leaving cell and to destabilize the molecule

Cleavage: 6 carbon molecules broken into 2, 3 carbon molecules of glyceraldehyde-3-phosphate

Energy liberation: two glyceraldehyde-3-phosphate molecules broken down into two pyruvate molecules

57
Q

In what 2 different phases of respiration do you see substrate-level phosphorylation creating ATP?

A

Glycolysis and the CAC

58
Q

What would happen if you had no oxaloacetate in your system?

A

If oxaloacetate is removed from the cycle for glucose synthesis, it must be replaced. If there’s not enough oxaloacetate available to form citrate, the rate of acetyl-CoA metabolism, and hence the rate of the formation of ATP will slow down if not stop

59
Q

In which portions of the cell are the 4 phases of respiration occurring?

A

Glycolysis happens in the cytosol

Breakdown of pyruvate: mitochondrial matrix

CAC: mitochondrial matrix

Oxidative phosphorylation: the five types of protein complexes that bridge the space between the mitochondrial matrix and the intermembrane space

60
Q

What would happen if you had no oxygen available for respiration? What step of respiration is impacted? Where in the cell is this impacted?

A

Anaerobic respiration would occur because oxygen couldn’t be the final electron acceptor. Oxidative phosphorylation would be affected in the mitochondria

61
Q

Explain the process of how the carbon in glucose is released as carbon dioxide.

A

glucose is broken down in glycolysis

62
Q

What would happen to a cell if the cristae were damaged?

A

The ETC prolly wouldn’t be able to work

63
Q

FADH2 is made during –
a. Glycolysis
b. Pyruvate oxidation
c. Citric Acid Cycle
d. All of the above

A

c. Citric Acid Cycle

64
Q

During which of the following steps is no ATP made–
a. Glycolysis
b. Electron transport chain
c. Pyruvate oxidation
d. Citric Acid Cycle
e. ATP is made during all the steps

A

c. Pyruvate Oxidation

65
Q

What is the function of NADH and FADH2 ?
a. Charging electrons to power ATP synthase
b. Catalyzing the formation of acetyl-CoA
c. Providing electrons and H+ to the electron transport chain
d. Transporting CO2 into the mitochondria
e. Acting as a terminal electron acceptor

A

c. Providing electrons and H+ to the electron transport chain

66
Q

How does substrate level phosphorylation differ from oxidative phosphorylation ?
a. Oxidative makes ADP
b. Substrate level requires oxygen
c. Oxidative occurs during glycolysis only
d. Substrate level uses PO4 from a donor molecule only
e. All of the above are correct

A

d. Substrate level uses PO4 from a donor molecule only???

67
Q

Cyanide inhibits cytochrome oxidase (Complex IV). Why is this lethal?
a. NAD+ can no longer be reduced to NADH
b. Electron transport chain is shut down
c. Glycolysis is inhibited
d. Citric Acid Cycle cannot be initiated
e. Pyruvate is not converted to Acetyl-CoA

A

b. Electron transport chain is shut down
Cyanide binds to an electron carrier and blocks the movement of electrons, resulting in a halt of eventually all steps in the process

68
Q

What happens to the electrons energy as it moves through the electron transport chain?
a. The electrons gain energy through each transfer
b. The electrons lose energy through each transfer
c. The energy content is unchanged
d. The energy drops to a different orbital

A

b. The electrons lose energy through each transfer

BIOL150 (15 decks)

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