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Bioenergetics Flashcards

1
Q

What is the primary pigment responsible for capturing light energy in plants?

A

chlorophyll

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2
Q

Where does photosynthesis occur in plants?

A

Photosynthesis occurs in the mesophyll cells of plants, specifically in the chloroplasts

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3
Q

What are the two sets of reactions involved in photosynthesis?

A

The two sets of reactions involved in photosynthesis are the light-dependent reactions and the light-independent reactions (Calvin cycle).

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4
Q

What happens during the light-dependent reactions of photosynthesis?

A

During the light-dependent reactions, light energy is absorbed by chlorophyll and used to split water molecules, producing oxygen, hydrogen ions (H+), ATP, and NADPH.

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5
Q

How is water involved in the light-dependent reactions?

A

Water molecules are split during the light-dependent reactions, releasing oxygen (O2) and providing electrons and hydrogen ions (H+) for the production of ATP and NADPH.

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6
Q

What are the products of the light-dependent reactions?

A

oxygen (O2), ATP (adenosine triphosphate), and NADPH (nicotinamide adenine dinucleotide phosphate).

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7
Q

Where do the light-independent reactions (Calvin cycle) occur?

A

The light-independent reactions (Calvin cycle) occur in the stroma of the chloroplasts.

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8
Q

How does the Calvin cycle utilize ATP and NADPH?

A

The Calvin cycle utilizes ATP and NADPH produced during the light-dependent reactions to convert carbon dioxide (CO2) into glucose (C6H12O6) through a series of chemical reactions.

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9
Q

What is the end product of the light-independent reactions?

A

The end product of the light-independent reactions is glucose (C6H12O6).

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10
Q

How many molecules of carbon dioxide are needed to produce one molecule of glucose in the Calvin cycle?

A

Six molecules of carbon dioxide (CO2) are needed to produce one molecule of glucose (C6H12O6) in the Calvin cycle.

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11
Q

What are the main products of cellular respiration?

A

are carbon dioxide (CO2), water (H2O), and energy in the form of ATP.

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12
Q

How is glucose broken down in cellular respiration?

A

In the presence of oxygen, glucose undergoes glycolysis, where it is converted into two molecules of pyruvic acid. Pyruvic acid then enters the Krebs Cycle (Citric Acid Cycle) and is further broken down to release energy.

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13
Q

What is the role of oxygen in cellular respiration

A

Oxygen plays a crucial role in cellular respiration as the final electron acceptor in the electron transport chain. It combines with electrons and hydrogen ions to form water, allowing the electron transport chain to continue functioning and producing ATP.

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14
Q

Explain the process of glycolysis and where it takes place.

A

Glycolysis is the process of breaking down glucose into two molecules of pyruvic acid. It takes place in the cytoplasm of cells.

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15
Q

What is the net gain of ATP in glycolysis?

A

The net gain of ATP in glycolysis is 2 ATP molecules.

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16
Q

Describe the process of fermentation and its significance when oxygen is not available.

A

Fermentation occurs when oxygen is not available for cellular respiration. It is an alternative pathway that allows the production of ATP without oxygen. In organisms like yeasts, alcohol is produced during fermentation. In our muscles, lactic acid is produced.

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17
Q

What is the Krebs Cycle (Citric Acid Cycle) and where does it occur?

A

is a series of reactions that occur in the mitochondria. It involves the further breakdown of pyruvic acid and the release of energy in the form of ATP, NADH, and FADH2.

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18
Q

What are the products of the Krebs Cycle?

A

The products of the Krebs Cycle are ATP, NADH, FADH2, and carbon dioxide (CO2).

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19
Q

How does the electron transport chain contribute to ATP production?

A

The electron transport chain plays a crucial role in ATP production. NADH and FADH2 from glycolysis and the Krebs Cycle donate electrons to the electron transport chain. As electrons move through the chain, energy is released, which is used to pump hydrogen ions (H+) across the mitochondrial membrane. This creates a concentration gradient that drives ATP synthesis.

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20
Q

What are the roles of NADH and FADH2 in cellular respiration?

A

NADH and FADH2 are electron carriers in cellular respiration. They play a key role in transferring electrons and hydrogen ions to the electron transport chain, where the energy from these molecules is used to produce ATP.

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21
Q

How do coenzymes NAD+ and FAD participate in cellular respiration?

A

Coenzymes NAD+ and FAD participate in cellular respiration by accepting electrons and hydrogen ions during oxidation reactions. They are reduced to NADH and FADH2, respectively, and carry these energy-rich molecules to the electron transport chain.

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22
Q

Explain the role of the electron transport chain in capturing energy and producing ATP.

A

The electron transport chain captures the energy released during the transfer of electrons and uses it to produce ATP. As electrons pass through the chain, energy is used to pump hydrogen ions across the mitochondrial membrane. The flow of these ions back through ATP synthase generates ATP.

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23
Q

Why is the transfer of electrons down the electron transport chain energetically favored?

A

The transfer of electrons down the electron transport chain is energetically favored because NADH is a strong electron donor, and oxygen is a highly efficient electron acceptor. This flow of electrons releases energy, which is utilized for ATP production.

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24
Q

What is the final electron acceptor in cellular respiration?

A

The final electron acceptor in cellular respiration is oxygen (O2).

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25
Q

Why does the flow of electrons from NADH to oxygen not directly result in ATP synthesis?

A

Although the flow of electrons from NADH to oxygen releases energy, it does not directly result in ATP synthesis. Instead, the energy is used to create a proton gradient across the mitochondrial membrane, which is then harnessed by ATP synthase to produce ATP through a process called chemiosmosis.

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26
Q

The text states, “The flow of electrons from NADH to oxygen does not directly result in ATP synthesis.” This statement is incorrect. In reality, the flow of electrons from NADH to oxygen in the electron transport chain is what drives ATP synthesis through a process called oxidative phosphorylation. This process utilizes the energy from electron transfer to establish a proton gradient, which is then used by ATP synthase to produce ATP. I apologize for the misinformation in the previous response

A
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27
Q

1 calorie = 1000 kilo calories

A
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28
Q

The energy from food needs to be released slowly and stored in the form of ATP (adenosine triphosphate) molecules.

A
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29
Q

Net ATP gain in glycolysis I. E + HARD is

A

+ 2 NADP = 7
I. E 2 ATP & 2 NADP

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30
Q

In our muscles, fermentation produces

A

lactic acid.

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31
Q

In the presence of oxygen, pyruvate molecules are modified and transported into

A

the mitochondria.

32
Q

FADH2 yields 1.5 ATP

A
33
Q

ATP (adenosine triphosphate) itself is not directly utilized as a source of energy in the electron transport chain (ETC).

A
34
Q

ATP is produced as a result of the electron transport chain through a process called

A

oxidative phosphorylation.

35
Q

The metabolic intermediates of these reactions donate electrons to
specific

coenzymes—nicotinamide
adenine dinucleotide (NAD+) and
flavin adenine dinucleotide
(FAD)—to form the energy-rich reduced
coenzymes, NADH and FADH2.

A
36
Q

Difference between substrate phosphorylation and oxidative phosphorylation

A

SP–ATP is directly produced by the transfer of a phosphate group from a phosphorylated substrate to ADP, forming ATP.– 2ATP– cytoplasm of cells
OP–its synthesisee from ATP synthase –26-28 ATP– inner mitochondrial membrane, specifically

37
Q

What is the chemiosmotic hypothesis and why is it important in cellular energy production?

A

The chemiosmotic hypothesis is a scientific explanation for how cells produce ATP using the energy generated during electron transport. It is important because it provides a mechanistic understanding of how cellular energy production occurs in mitochondria.

38
Q

How is electron transport coupled to the phosphorylation of ADP in the chemiosmotic hypothesis?

A

Electron transport is coupled to the phosphorylation of ADP by the transport of protons across the inner mitochondrial membrane. As electrons are transported through specific complexes in the electron transport chain (Complexes I, III, and IV), protons are pumped from the matrix to the intermembrane space. This movement of protons creates a proton gradient, which is used to drive ATP synthesis.

39
Q

Which complexes in the electron transport chain are involved in the pumping of protons across the inner mitochondrial membrane

A

Complexes I, III, and IV in the electron transport chain are involved in the pumping of protons across the inner mitochondrial membrane.

40
Q

What is the purpose of creating an electrical and pH gradient across the inner mitochondrial membrane?

A

The creation of an electrical and pH gradient across the inner mitochondrial membrane serves as a means of storing energy. The buildup of positively charged protons on the outside of the membrane and the lower pH (higher acidity) outside compared to the inside creates a gradient of potential energy that can be utilized for ATP synthesis.

41
Q

How does the proton gradient serve as a mediator between oxidation and phosphorylation?

A

The proton gradient acts as the intermediate that links the process of electron transport (oxidation) to the production of ATP (phosphorylation). The energy stored in the proton gradient is harnessed to drive the synthesis of ATP.

42
Q

Explain the coupling of electron transport and ADP phosphorylation in the context of the chemiosmotic hypothesis.

A

The coupling of electron transport and ADP phosphorylation occurs through the proton pump. As electrons are transported through the electron transport chain, protons are pumped across the inner mitochondrial membrane, creating a proton gradient. The energy from this gradient is then used to phosphorylate ADP and convert it into ATP.

43
Q

What are the key components of the chemiosmotic hypothesis proposed by Peter Mitchell?

A

The key components of the chemiosmotic hypothesis proposed by Peter Mitchell include the concept of electron transport generating a proton gradient, the coupling of electron transport and ATP synthesis through the proton pump, and the role of the proton gradient as the mediator between oxidation and phosphorylation.

44
Q

there is a buildup of positively charged protons on the outside of the membrane and a lower pH (higher acidity) outside compared to the inside.

A
45
Q

What is the role of ATP synthase in cellular energy production?

A

The role of ATP synthase is to produce ATP, the main energy currency of the cell, using the energy derived from the proton gradient generated by the electron transport chain.

46
Q

Which complex is responsible for synthesizing ATP?

A

ATP synthase, also known as Complex V, is the enzyme complex responsible for synthesizing ATP

47
Q

How does ATP synthase utilize the proton gradient generated by the electron transport chain?

A

ATP synthase utilizes the proton gradient generated by the electron transport chain by allowing protons to reenter the matrix through a channel in the membrane-spanning domain (Fo) of Complex V. This proton movement drives the rotation of the Fo domain.

48
Q

What is the proposed mechanism for protons reentering the matrix through ATP synthase?

A

The chemiosmotic hypothesis proposes that protons reenter the matrix through ATP synthase by passing through a channel in the Fo domain of Complex V.

49
Q

Which domain of ATP synthase is involved in the rotation process?

A

The Fo domain of ATP synthase is involved in the rotation process.

50
Q

How do conformational changes in the F1 domain contribute to ATP synthesis?

A

Conformational changes in the extra-membranous F1 domain of ATP synthase occur due to the rotation of the Fo domain. These changes enable the F1 domain to bind ADP (adenosine diphosphate) and Pi (inorganic phosphate), leading to the phosphorylation of ADP and the formation of ATP

51
Q

What are the substrates of ATP synthase, and what is the product of its activity?

A

The substrates of ATP synthase are ADP and Pi, and the product of its activity is ATP

52
Q

How is ATP released from ATP synthase?

A

ATP is released from ATP synthase once it has been synthesized and is ready to be used as an energy source by the cell.

53
Q

How is ATP released from ATP synthase?

A

ATP is released from ATP synthase once it has been synthesized and is ready to be used as an energy source by the cell.

54
Q

List the inhibitors you know

A

Oligomysin
UCP1
4-dinitrophenol, a lipophilic
proton carrier that readily diffuses

through the mitochondrial membrane

55
Q

What is respiratory control and how is it related to the coupling of processes in cellular respiration?

A

A: Respiratory control refers to the dependency of cellular respiration on the ability to phosphorylate ADP to ATP. It is the consequence of the tight coupling between electron transport and phosphorylation processes. Inhibition of one process, such as by oligomycin, will also inhibit the other process due to their interdependence.

56
Q

What is the function of oligomycin in inhibiting the electron transport chain?

A

A: Oligomycin binds to ATP synthase, blocking the H+ channel and preventing the entry of protons into the mitochondrial matrix. This inhibits the phosphorylation of ADP to ATP and stops electron transport due to the difficulty of pumping protons against the steep gradients.

57
Q

How do uncoupling proteins (UCPs) affect ATP synthesis?

A

A: Uncoupling proteins allow protons to re-enter the mitochondrial matrix without being used to produce ATP. Instead, the energy is released as heat, a process known as non-shivering thermogenesis. UCP1, in particular, is responsible for heat production in brown adipocytes and is activated by fatty acids.

58
Q

What is the role of synthetic uncouplers in the electron transport chain?

A

A: Synthetic uncouplers increase the permeability of the inner mitochondrial membrane to protons, disrupting the establishment of a proton gradient. This allows electron transport to proceed rapidly without the generation of ATP. Similar to uncoupling proteins, energy is released as heat rather than being used for ATP synthesis.

59
Q

How do high doses of aspirin and salicylates affect oxidative phosphorylation?

A

A: High doses of aspirin and salicylates can uncouple oxidative phosphorylation, disrupting the coupling between electron transport and ATP synthesis. This can result in the release of heat and may explain the fever experienced during toxic overdoses of these drugs.

60
Q

4-dinitrophenol causes

A

This uncoupler causes electron transport to proceed
at a rapid rate without establishing a proton gradient as much as UCP

61
Q

Defects in oxidative phosphorylation are often caused

A

by changes in mitochondrial DNA (mtDNA).

62
Q

Oxidative defeats often affect what organs

A

central nervous system, skeletal and heart muscles, kidney, and liver,

63
Q

Mutations in mtDNA can lead to diseases like

A

mitochondrial myopathies and Leber hereditary optic neuropathy, which causes central vision loss.

64
Q

Apoptosis can be initiated through the intrinsic pathway,

A

the formation of pores in the outer mitochondrial membrane.
These pores allow cytochrome c to move from the intermembrane space to the cytosol.

In the cytosol, cytochrome c, along with pro-apoptotic factors, activates caspases, leading to the cleavage of key proteins and the characteristic changes of apoptosis.

65
Q

How is mtDNA inherited?

A

A: mtDNA is maternally inherited, meaning it is passed down from the mother. Mitochondria from the sperm cell do not enter the fertilized egg.

66
Q

What role does cytochrome c play in apoptosis?

A

A: In the cytosol, cytochrome c, along with pro-apoptotic factors, activates caspases, which are a group of enzymes that cause cleavage of key proteins, leading to the morphological and biochemical changes characteristic of apoptosis.

67
Q

What does free energy (ΔG) represent in bioenergetics?

A

Free energy (ΔG) represents the energetic feasibility of a chemical reaction or process

68
Q

How are enthalpy (ΔH) and entropy (ΔS) related to the direction of a chemical reaction?

A

Enthalpy (ΔH) represents the change in heat content, while entropy (ΔS) represents the change in randomness or disorder. The combination of these factors determines the direction and extent of a chemical reaction.

69
Q

What is the difference between an exergonic and an endergonic reaction?

A

An exergonic reaction is spontaneous, with a negative ΔG, resulting in a net loss of energy. An endergonic reaction is non-spontaneous, with a positive ΔG, requiring an input of energy for the reaction to occur.

70
Q

How can ΔG be used to predict the direction of a reaction?

A

ΔG can be used to predict the direction of a reaction by comparing its value to zero. If ΔG is negative, the reaction is spontaneous in the forward direction; if ΔG is positive, the reaction is non-spontaneous; and if ΔG is zero, the reactants are in equilibrium.

71
Q

How are reactions with large positive ΔG made possible?

A

Reactions with large positive ΔG can occur by coupling them with a second process with a large negative ΔG. This means that the energy released from the exergonic process can be used to drive the endergonic process.

72
Q

n example of coupling an endergonic process with an exergonic process is the movement of ions against a concentration gradient across a cell membrane. This is made possible by coupling it with the exergonic hydrolysis of ATP, which provides the necessary energy.

A
73
Q

An example of coupling an endergonic process with an exergonic process is the movement of ions against a concentration gradient across a cell membrane. This is made possible by coupling it with the exergonic hydrolysis of ATP, which provides the necessary energy.

A
74
Q

What are the changes in enthalpy (ΔH) and entropy (ΔS) during

A

Enthalpy (ΔH) and entropy (ΔS) changes occur during oxidative phosphorylation. ΔH is influenced by the redox reactions in the electron transport chain, where electrons are transferred from electron donors (NADH and FADH2) to electron acceptors (oxygen). ΔS is influenced by the movement of protons across the mitochondrial membrane, which contributes to the entropy change.

75
Q

Can you explain the process of oxidative phosphorylation in terms of ΔG and the concept of exergonic and endergonic reactions?

A

Oxidative phosphorylation can be considered an exergonic reaction as it involves the release of energy. The electron transport chain and proton gradient formation contribute to the exergonic part, while ATP synthesis is the endergonic part. The coupling of these processes allows for the overall exergonic reaction of oxidative phosphorylation.

76
Q

Enthalpy is influenced by the redox reactions in the electron transport chain, while entropy is influenced by the movement of protons across the mitochondrial membrane.

A

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