Module 2 Flashcards
(330 cards)
1
Q
What does ATP stand for?
A
Adenosine triphosphate
2
Q
What type of biomolecule is ATP?
A
Nucleotide
3
Q
What are the three components of ATP?
A
Adenine, ribose, phosphate groups
4
Q
What happens when ATP is hydrolyzed?
A
It releases energy and forms ADP + Pi
5
Q
Which enzyme hydrolyzes ATP?
A
ATPase
6
Q
What is the ΔG° of ATP hydrolysis?
A
-30.5 kJ/mol
7
Q
Why is ATP a high-energy molecule?
A
Charge repulsion between phosphate groups
8
Q
What is ATP used for in cells?
A
Active transport, muscle contraction, biosynthesis
9
Q
How does ATP drive unfavorable reactions?
A
By coupling with exergonic reactions
10
Q
What is an example of an ATP-driven reaction?
A
Phosphorylation of glucose by hexokinase
11
Q
What is a phosphoryl group transfer?
A
Movement of a phosphate from ATP to another molecule
12
Q
Which enzyme transfers phosphate groups from ATP?
A
Kinase
13
Q
What is primary active transport?
A
Transport powered directly by ATP hydrolysis
14
Q
What is an example of primary active transport?
A
Na+/K+ ATPase pump
15
Q
What is secondary active transport?
A
Transport driven by an ion gradient
16
Q
What is an example of secondary active transport?
A
Glucose-sodium symport
17
Q
Where does the ETC occur?
A
Inner mitochondrial membrane
18
Q
What is the role of the ETC?
A
Generate a proton gradient for ATP synthesis
19
Q
What is the final electron acceptor in the ETC?
A
Oxygen
20
Q
What are the four complexes in the ETC?
A
Complex I, II, III, IV
21
Q
What is the role of Complex I?
A
Transfers electrons from NADH to ubiquinone
22
Q
What is the role of Complex II?
A
Transfers electrons from FADH2 to ubiquinone
23
Q
What is the role of Complex III?
A
Transfers electrons from ubiquinol to cytochrome c
24
Q
What is the role of Complex IV?
A
Transfers electrons to oxygen, forming water
25
What is the function of cytochrome c?
Transfers electrons from Complex III to IV
26
What is chemiosmosis?
Proton movement through ATP synthase to drive ATP synthesis
27
What are the two domains of ATP synthase?
F0 (membrane-bound) and F1 (catalytic)
28
What drives ATP synthase rotation?
Proton flow
29
What happens in the “Tight” state of ATP synthase?
ATP is synthesized
30
How many protons are needed to make 1 ATP?
4 protons
31
What are the two stages of photosynthesis?
Light reactions and Calvin cycle
32
What is the main pigment in photosynthesis?
Chlorophyll
33
What is photophosphorylation?
ATP production using light energy
34
Where does the Calvin cycle occur?
Stroma
35
What is RuBisCO’s function?
Catalyzes carbon fixation
36
What is the main finding of the ATP synthase rotor study?
ATP synthase functions as a rotary motor
37
What technique was used to visualize ATP synthase rotation?
Fluorescent actin filaments attached to the γ-subunit
38
How did researchers confirm unidirectional rotation?
By tracking actin filament movement over multiple revolutions
39
Which subunit of ATP synthase rotates?
The γ-subunit
40
Why was a fluorescent actin filament used?
To make rotation visible under a microscope
41
What experimental control confirmed that ATP was needed for rotation?
No ATP = no rotation
42
What is the purpose of the α3β3 hexamer in ATP synthase?
Forms the catalytic core for ATP synthesis
43
What happened when ATP was added to isolated F1-ATPase?
The γ-subunit rotated counterclockwise
44
How did researchers measure the torque generated by ATP synthase?
By observing the resistance of the actin filament to rotation
45
What did Brownian motion fluctuations indicate in the experiment?
That rotation is driven by ATP hydrolysis, not random diffusion
46
What direction does the γ-subunit rotate during ATP synthesis?
Clockwise
47
What direction does the γ-subunit rotate during ATP hydrolysis?
Counterclockwise
48
What effect did azide have in the experiment?
It inhibited ATP hydrolysis, stopping rotation
49
What role does the stator (b-subunit) play in ATP synthase?
Holds the α3β3 hexamer in place to prevent rotation
50
What was a major limitation of the rotor experiment?
The actin filament added mechanical load, affecting natural speed
51
What is the estimated torque of ATP synthase?
~40 pN·nm
52
What was the goal of the second ATP synthase study?
To demonstrate that mechanical force can drive ATP synthesis
53
How did researchers force ATP synthesis?
By rotating F1-ATPase using a magnetic bead
54
What was used to detect ATP production?
The luciferase-luciferin reaction
55
How did they confirm that rotation direction mattered for ATP synthesis?
Only clockwise rotation resulted in ATP production
56
Why were histidine tags used in this study?
To anchor ATP synthase to a glass surface
57
What role did biotin-streptavidin interactions play in the experiment?
They attached magnetic beads to the γ-subunit
58
What frequency of rotation optimized ATP synthesis?
3-10 Hz
59
What was the significance of using an oil-based microdroplet system?
It allowed detection of ATP production in a confined space
60
Why did ATP production stop when rotation was paused?
ATP synthesis requires continuous mechanical force
61
How did researchers determine the efficiency of mechanical ATP synthesis?
By comparing ATP yield to input torque
62
What does this experiment suggest about ATP synthase in vivo?
That proton-driven rotation follows the same mechanistic principles
63
What molecule did the experiment use instead of a natural proton gradient?
Magnetic force to drive mechanical rotation
64
Why was NADP+ used as a control in the experiment?
To verify ATP was being synthesized, not an artifact of other reactions
65
What does this experiment confirm about the reversibility of ATP synthase?
It can work both ways
66
Why is the mechanical synthesis of ATP significant?
It shows ATP synthase is fully reversible and can act as a generator
67
What was a major challenge in proving mechanical ATP synthesis?
Ensuring that ATP was not contaminating the reaction mixture
68
What are potential applications of mechanical ATP synthesis?
Synthetic bioenergy systems and nanotechnology
69
What problem affects cassava production?
Cyanogenic glycosides that release toxic HCN
70
How does ATP play a role in cassava detoxification?
ATP-dependent enzymes convert cyanogenic compounds
71
What enzyme in cassava releases cyanide?
Linamarase
72
What environmental conditions increase cyanogenic glycosides in cassava?
Drought stress
73
What genetic modifications could reduce cyanide levels in cassava?
Engineering plants to express lower levels of cyanogenic compounds
74
What is the relationship between ATP and cyanide detoxification in humans?
Cyanide blocks ATP production by inhibiting Complex IV of the ETC
75
How does cyanide poisoning affect ATP production?
It blocks the electron transport chain
76
What is an ATP-related disease?
Mitochondrial disorders
77
What is ATP's role in apoptosis?
Required for caspase activation
78
What is the effect of uncouplers like DNP on ATP production?
They reduce ATP synthesis and generate heat
79
What is substrate-level phosphorylation?
ATP production by direct phosphate transfer in glycolysis and the Krebs cycle (doesn’t undergo oxidative phosphorylation)
80
What is oxidative phosphorylation?
ATP synthesis powered by the electron transport chain
81
What is the role of NADH and FADH2 in metabolism?
Electron carriers that transfer energy to the ETC
82
How many ATP molecules are produced per glucose molecule in cellular respiration?
30-32 ATP
83
What is the role of oxygen in oxidative phosphorylation?
Final electron acceptor that forms water
84
What are the three main steps of cellular respiration?
Glycolysis, Krebs cycle, oxidative phosphorylation
85
What is the role of Coenzyme Q (Ubiquinone) in the ETC?
Shuttles electrons between Complexes I/II and III
86
How does ATP synthase couple proton flow with ATP synthesis?
Protons drive conformational changes in the enzyme to generate ATP
87
What is the significance of the proton gradient in mitochondria?
Stores energy for ATP production
88
How does cyanide affect cellular respiration?
Inhibits Complex IV, blocking oxygen reduction and stopping ATP production
89
What is the Warburg effect?
Cancer cells rely on glycolysis for ATP even in the presence of oxygen
90
What is an example of an uncoupling agent?
2,4-DNP (Dinitrophenol)
91
How do uncoupling agents affect ATP synthesis?
They dissipate the proton gradient, reducing ATP production but increasing heat generation
92
How does mitochondrial dysfunction impact ATP production?
It decreases ATP yield and increases reactive oxygen species (ROS)
93
What is the primary function of the Krebs cycle?
Generate high-energy electron carriers for the ETC
94
How many NADH molecules are produced per glucose in the Krebs cycle?
6 NADH
95
How many FADH2 molecules are produced per glucose in the Krebs cycle?
2 FADH2
96
What is the net ATP gain from glycolysis?
2 ATP
97
What is the total ATP yield from the Krebs cycle per glucose?
2 ATP
98
What are the main products of the Krebs cycle per glucose?
6 NADH, 2 FADH2, 2 ATP, 4 CO2
99
What is the function of Complex III in the electron transport chain?
Transfers electrons from ubiquinol to cytochrome c
100
How does ATP synthase work as a reversible enzyme?
It can both synthesize and hydrolyze ATP depending on the proton gradient
101
What is the function of ATPase inhibitors like oligomycin?
They block the proton channel in ATP synthase, stopping ATP production
102
How does rotenone affect the ETC?
It inhibits Complex I, preventing NADH oxidation
103
How does carbon monoxide (CO) affect the ETC?
It binds to Complex IV, blocking oxygen binding and electron transfer
104
What are reactive oxygen species (ROS) and how do they form in mitochondria?
Harmful byproducts of electron transport formed when electrons leak from the ETC
105
What enzyme converts superoxide radicals into less harmful molecules?
Superoxide dismutase (SOD)
106
How does the body prevent excessive ROS damage?
Antioxidant enzymes like catalase and glutathione peroxidase neutralize ROS
107
What is the role of ATP in muscle contraction?
Provides energy for myosin-actin interactions
108
What is creatine phosphate’s function in ATP metabolism?
It acts as a quick ATP reserve in muscle cells
109
What is ATP’s role in nerve signaling?
Powers ion pumps like Na+/K+ ATPase to maintain resting membrane potential
110
What is ATP’s function in biosynthesis?
Provides energy for anabolic reactions like protein and DNA synthesis
111
How does ATP impact cellular homeostasis?
Maintains ion gradients and drives essential biochemical reactions
112
What is ATP turnover rate in a typical human cell?
Each ATP molecule is recycled 1000-1500 times per day
113
How do mitochondria generate heat instead of ATP?
Via uncoupling proteins that allow proton flow without ATP synthesis
114
What is the significance of brown adipose tissue in thermogenesis?
It uses uncoupling proteins to generate heat instead of storing energy as ATP
115
What is the primary function of the Calvin cycle?
Fix carbon dioxide into organic molecules
116
What is the main energy input for the Calvin cycle?
ATP and NADPH from light reactions
117
What are the three phases of the Calvin cycle?
Carbon fixation, reduction, regeneration of RuBP
118
How many ATP molecules are required to produce one glucose in the Calvin cycle?
18 ATP
119
What are the main products of the light-dependent reactions?
ATP, NADPH, and O2
120
What molecule is split during photosynthesis to produce oxygen?
Water (H2O)
121
What is the role of Photosystem II in photosynthesis?
Generates high-energy electrons and splits water to produce oxygen
122
How does ATP synthase function in chloroplasts?
Uses the proton gradient across the thylakoid membrane to synthesize ATP
123
How does cyclic photophosphorylation differ from non-cyclic photophosphorylation?
Cyclic only produces ATP (only involves PSI), while non-cyclic produces both ATP and NADPH
124
What is the function of plastoquinone in photosynthesis?
Electron carrier between Photosystem II and the cytochrome b6f complex
125
What happens to electrons at the end of the electron transport chain in photosynthesis?
They reduce NADP+ to NADPH
126
What is the role of the cytochrome b6f complex in photosynthesis?
Transfers electrons and pumps protons to generate a proton gradient
127
How does ATP synthesis in chloroplasts compare to mitochondria?
Both use a proton gradient, but mitochondria use oxidative phosphorylation while chloroplasts use photophosphorylation
128
What is the key difference between ATP production in cellular respiration vs. photosynthesis?
Respiration breaks down glucose to make ATP, photosynthesis uses light energy to build glucose
129
What is the primary goal of the case study on cassava?
Understand ATP’s role in detoxifying cyanogenic compounds
130
Why does cassava contain cyanogenic glycosides?
Defense mechanism against herbivores
131
How does linamarase contribute to cyanide production in cassava?
It breaks down linamarin into toxic cyanide
132
How does processing reduce cassava’s cyanide content?
Soaking, fermentation, and cooking remove cyanogenic compounds
133
What is ATP’s role in cassava detoxification?
Powers enzymes that metabolize cyanogenic glycosides into non-toxic compounds
134
What conditions increase cyanide levels in cassava?
Drought and nutrient deficiency
135
How does ATP influence stress responses in plants like cassava?
Powers metabolic adjustments to environmental stress
136
How could genetic engineering reduce cyanide in cassava?
By modifying ATP-dependent detoxification pathways
137
What are the health risks of consuming improperly processed cassava?
Cyanide poisoning, leading to neurological damage or death
138
What is konzo, and how is it linked to cassava?
A neurological disorder caused by chronic cyanide exposure from cassava
139
How can ATP studies help improve food security?
Understanding ATP metabolism can enhance crop detoxification and nutrient efficiency
140
What was a major experimental challenge in proving ATP synthase’s rotor function?
Ensuring external forces did not interfere with natural rotation
141
How does ATP synthase respond to proton gradients in different environments?
It adjusts rotation speed based on gradient strength
142
What is a potential application of ATP synthase research in medicine?
Targeting mitochondrial dysfunction in diseases like Parkinson’s
143
How does ATP synthase relate to nanotechnology?
Inspires bioengineered molecular motors
144
How does ATP synthase efficiency compare to synthetic energy systems?
It operates near 100% efficiency, far higher than most man-made motors
145
What future research could build on ATP synthase discoveries?
Engineering artificial ATP-powered molecular machines
146
What is the function of the adenine nucleotide pool in cells?
Maintains ATP, ADP, and AMP balance for energy regulation
147
Why is ATP kinetically stable despite being thermodynamically unstable?
High activation energy prevents spontaneous hydrolysis
148
What is the role of ATP in signal transduction?
Phosphorylates proteins to activate signaling pathways
149
How does ATP hydrolysis drive molecular motors like myosin and kinesin?
Provides energy for conformational changes that enable movement
150
What is an example of an ATP-dependent transport protein?
ABC transporters that move molecules across membranes
151
How does the Na+/K+ ATPase contribute to nerve impulses?
Maintains ion gradients essential for action potentials
152
What is the function of P-type ATPases?
Use ATP to transport ions like Na+, K+, Ca2+ across membranes
153
What is the role of ATP in metabolic regulation?
Acts as an allosteric regulator of key enzymes
154
How does ATP influence glycolysis?
High ATP levels inhibit phosphofructokinase, slowing glycolysis
155
How does ATP regulate the Krebs cycle?
Inhibits citrate synthase and isocitrate dehydrogenase to reduce cycle activity
156
What is the role of AMP-activated protein kinase (AMPK)?
Senses low energy levels and activates ATP-generating pathways
157
How does ATP impact protein synthesis?
Provides energy for ribosome function and peptide bond formation
158
What is the ATP requirement for charging a tRNA molecule?
One ATP per amino acid activation
159
What role does ATP play in RNA transcription?
Provides energy for RNA polymerase to synthesize RNA strands
160
How does ATP influence DNA replication?
Powers helicase enzymes that unwind the DNA double helix
161
What is the importance of ATP in cell division?
Drives mitotic spindle assembly and chromosome movement
162
What is the ATP cost of assembling a single polypeptide chain?
One ATP per peptide bond plus additional for initiation and elongation
163
What is ATP's role in maintaining membrane potential?
Powers ion pumps that establish electrochemical gradients
164
How does ATP function in endocytosis and exocytosis?
Provides energy for vesicle formation and fusion
165
What is ATP's function in apoptosis (programmed cell death)?
Drives caspase activation and DNA fragmentation
166
What is the ATP yield from anaerobic respiration?
2 ATP per glucose (from glycolysis only)
167
How does the electron transport chain maximize ATP production efficiency?
Uses stepwise electron transfer to minimize energy loss as heat
168
What is the function of the Q cycle in Complex III of the ETC?
Transfers electrons between ubiquinol and cytochrome c while pumping protons
169
How does the ETC prevent electron leakage that leads to ROS formation?
Tightly regulated electron flow through complexes I-IV
170
What is the role of cytochrome oxidase (Complex IV)?
Catalyzes oxygen reduction to water while pumping protons
171
How does ATP synthase adjust ATP production based on demand?
Regulates rotation speed according to proton motive force strength
172
What is the effect of a defective ATP synthase enzyme?
Reduced ATP output, leading to energy deficiency in cells
173
How do mutations in ATP synthase contribute to mitochondrial diseases?
Cause ATP depletion, leading to neurological and muscular disorders
174
What is ATP's role in photosynthetic carbon fixation?
Provides energy for converting CO2 into organic molecules
175
How do C4 and CAM plants use ATP differently than C3 plants?
Require extra ATP for carbon fixation under dry conditions
176
What is the ATP cost of fixing one CO2 molecule in the Calvin cycle?
3 ATP per CO2 fixed
177
How does cyclic electron flow benefit plants under high light conditions?
Produces ATP without NADPH to balance energy demands
178
What happens when photosynthesis produces excess ATP?
It is used for cellular metabolism and biosynthesis
179
How does ATP regulate stomatal opening in plants?
Powers ion pumps that control guard cell turgor pressure
180
What is the significance of ATP in nitrogen fixation?
Provides energy for converting atmospheric nitrogen into ammonia
181
How does ATP influence root growth and nutrient uptake in plants?
Powers active transport of minerals into root cells
182
What is the connection between ATP and plant stress responses?
Supports protective mechanisms like antioxidant production
183
How does ATP function in bacterial flagellar movement?
Powers rotation of flagella for motility
184
What is the role of ATP in biofilm formation?
Supports bacterial adhesion and matrix production
185
How do ATP-binding cassette (ABC) transporters aid bacterial survival?
Transport nutrients and expel toxins using ATP energy
186
What is ATP's function in bacterial sporulation?
Provides energy for endospore formation under stress conditions
187
How does ATP contribute to antibiotic resistance in bacteria?
Powers efflux pumps that remove antibiotics from cells
188
What is the ATP yield per fatty acid molecule in β-oxidation?
More than glucose, typically ~106 ATP per palmitic acid
189
How does ATP regulate enzyme activity through phosphorylation?
Activates or inhibits enzymes by adding a phosphate group
190
What is the ATP cost of gluconeogenesis?
6 ATP per glucose synthesized
191
How does ATP influence lipid metabolism?
Powers fatty acid synthesis and triglyceride breakdown
192
What is the relationship between ATP and oxidative stress?
Low ATP levels can trigger oxidative damage and cell death
193
How does ATP control mitochondrial dynamics?
Regulates fusion and fission processes for energy adaptation
194
What is the ATP-dependent mechanism of heat generation in hibernating animals?
Thermogenesis via uncoupling proteins in brown fat
195
How is ATP linked to metabolic rate in different organisms?
Higher ATP turnover correlates with faster metabolism
196
What is the ATP role in circadian rhythm regulation?
Drives processes that control biological clocks in cells
197
What is the ATP function in bioluminescent organisms like fireflies?
Powers luciferase enzymes to produce light
198
How does ATP influence aging and longevity?
Declining ATP production is linked to cellular aging
199
What is the role of ATP in synthetic biology?
Used to engineer ATP-powered nanomachines and biosensors
200
How can ATP synthase research lead to new medical treatments?
Potential therapies for mitochondrial and neurodegenerative diseases
201
What is the relationship between ATP and CRISPR gene editing?
ATP is required for Cas9 enzyme activity in DNA modification
202
How could artificial ATP systems revolutionize energy production?
Development of ATP-powered bio-hybrid devices
203
What are future research directions for ATP metabolism studies?
Exploring ATP function in non-cellular energy storage and bioengineering
204
What are the two components of the electrochemical gradient in oxidative phosphorylation?
Proton concentration gradient and membrane potential
205
What is the first step of oxidative phosphorylation?
Electron transfer from NADH to Complex I
206
What is the second step of oxidative phosphorylation?
Electron transfer through the ETC, generating a proton gradient
207
What is the third step of oxidative phosphorylation?
Protons flow through ATP synthase, driving ATP production
208
What is the final step of oxidative phosphorylation?
Electrons are accepted by oxygen to form water
209
What is the structural function of the inner mitochondrial membrane in oxidative phosphorylation?
It houses the electron transport chain and ATP synthase
210
What is the function of Complex I (NADH dehydrogenase)?
Transfers electrons from NADH to ubiquinone and pumps protons
211
How many subunits does Complex I have?
Over 40 subunits
212
What happens if Complex I is inhibited?
NADH cannot be oxidized, halting electron flow and ATP production
213
What is the function of Complex II (Succinate dehydrogenase)?
Transfers electrons from FADH2 to ubiquinone without proton pumping
214
Why does Complex II not contribute to the proton gradient?
It does not span the membrane in a way that allows proton translocation
215
What is the function of Complex III (Cytochrome bc1 complex)?
Transfers electrons from ubiquinol to cytochrome c and pumps protons
216
How does Complex III contribute to oxidative phosphorylation efficiency?
It amplifies the proton gradient via the Q cycle
217
What is the function of Complex IV (Cytochrome c oxidase)?
Transfers electrons to oxygen, forming water and pumping protons
218
How many electrons are required to reduce one molecule of oxygen in Complex IV?
Four electrons
219
What is the function of cytochrome c in oxidative phosphorylation?
Shuttles electrons between Complex III and Complex IV
220
Why is cytochrome c critical for cell survival?
Its release from mitochondria triggers apoptosis
221
How does oxygen affect oxidative phosphorylation?
It is the final electron acceptor, allowing the ETC to function
222
What happens to oxidative phosphorylation in hypoxic conditions?
Electron transport slows or stops, reducing ATP production
223
What structural feature allows ATP synthase to rotate?
The asymmetric γ-subunit acts as a rotor
224
How does proton flow drive ATP synthesis in ATP synthase?
Protons move through the F0 channel, rotating the γ-subunit
225
What are the three conformations of ATP synthase’s β-subunits?
Loose (L), Tight (T), Open (O)
226
Which ATP synthase subunit forms the proton channel?
F0 subunit
227
What is the function of the F1 subunit in ATP synthase?
Catalyzes ATP synthesis
228
How does ATP synthase prevent ATP hydrolysis when the proton gradient is low?
It has an inhibitory protein that blocks reverse rotation
229
What are the inhibitors of Complex I in oxidative phosphorylation?
Rotenone and amytal
230
What are the inhibitors of Complex III in oxidative phosphorylation?
Antimycin A
231
What are the inhibitors of Complex IV in oxidative phosphorylation?
Cyanide, carbon monoxide, azide
232
How do uncouplers like DNP affect oxidative phosphorylation?
They dissipate the proton gradient, reducing ATP synthesis and increasing heat production
233
What happens if ATP synthase is inhibited?
Proton flow is blocked, stopping ATP synthesis despite an existing proton gradient
234
What structural feature of the mitochondria enhances oxidative phosphorylation efficiency?
The cristae provide a large surface area for ETC proteins
235
How does oxidative phosphorylation link to the Krebs cycle?
NADH and FADH2 from the Krebs cycle provide electrons for the ETC
236
Why does oxidative phosphorylation yield more ATP than glycolysis?
It uses the proton gradient to generate large amounts of ATP per glucose molecule
237
How does ATP yield differ between NADH and FADH2 oxidation?
NADH yields ~2.5 ATP, while FADH2 yields ~1.5 ATP
238
How does Complex IV prevent reactive oxygen species (ROS) formation?
It tightly controls electron transfer to oxygen
239
What happens if electron leakage occurs in the ETC?
ROS such as superoxide radicals form, causing oxidative stress
240
How do mitochondria protect against oxidative stress during oxidative phosphorylation?
Antioxidant enzymes like superoxide dismutase neutralize ROS
241
What is the impact of mitochondrial dysfunction on oxidative phosphorylation?
Leads to reduced ATP production and increased ROS damage
242
What cellular processes depend on oxidative phosphorylation for ATP?
Muscle contraction, nerve transmission, biosynthesis, and active transport
243
How do mitochondria regulate oxidative phosphorylation based on ATP demand?
By adjusting ETC activity and ATP synthase speed
244
What is the role of ADP concentration in controlling oxidative phosphorylation?
High ADP levels activate ATP synthase, increasing ATP production
245
What is respiratory control in oxidative phosphorylation?
The regulation of electron flow based on ATP and ADP levels
246
How does ATP synthase operate in reverse under certain conditions?
It hydrolyzes ATP to pump protons when necessary
247
What is the role of mitochondrial ATP-ADP translocase?
Exchanges ATP and ADP between the matrix and cytoplasm
248
How does the electron transport chain generate a proton-motive force?
By pumping protons from the matrix into the intermembrane space
249
How does the proton-motive force drive oxidative phosphorylation?
Provides the energy for ATP synthase to synthesize ATP
250
What is the function of the intermembrane space in oxidative phosphorylation?
Stores protons to maintain the proton gradient
251
How does oxidative phosphorylation contribute to heat generation?
Uncoupled respiration releases energy as heat
252
Why do brown fat cells have high oxidative phosphorylation activity?
They contain uncoupling proteins that generate heat instead of ATP
253
What is the role of uncoupling protein 1 (UCP1) in oxidative phosphorylation?
Allows protons to bypass ATP synthase, producing heat instead of ATP
254
How does oxidative phosphorylation change during exercise?
Increases ATP production to meet energy demands
255
Why do mitochondrial diseases often affect high-energy organs?
These organs (brain, muscles, heart) depend heavily on ATP from oxidative phosphorylation
256
How does oxidative phosphorylation differ in bacteria versus mitochondria?
Bacteria use their plasma membrane instead of mitochondria for the ETC
257
How do poisons like cyanide cause rapid death by inhibiting oxidative phosphorylation?
They block Complex IV, halting ATP production and causing cell death
258
How does oxidative phosphorylation support rapid cell growth in cancer cells?
Increased ATP production fuels biosynthetic pathways
259
Why do cancer cells rely on glycolysis more than oxidative phosphorylation?
Warburg effect
260
How is oxidative phosphorylation regulated at the genetic level?
Mitochondrial DNA encodes key ETC proteins
261
What happens when mitochondrial DNA mutations affect oxidative phosphorylation?
Leads to energy deficiencies and metabolic disorders
262
What role do mitochondrial fusion and fission play in oxidative phosphorylation?
Regulate efficiency by adjusting mitochondrial structure and function
263
How does mitochondrial biogenesis affect oxidative phosphorylation?
Increases the number of mitochondria to enhance ATP production
264
What is the role of peroxisomes in oxidative phosphorylation?
Support metabolism by reducing oxidative stress
265
How does oxidative phosphorylation impact lifespan and aging?
Declining efficiency contributes to aging and age-related diseases
266
How do calorie restriction and fasting enhance oxidative phosphorylation efficiency?
Increase mitochondrial efficiency and reduce ROS production
267
How does oxidative phosphorylation relate to neurodegenerative diseases like Parkinson’s and Alzheimer’s?
Mitochondrial dysfunction impairs ATP production and increases oxidative stress
268
Why is oxidative phosphorylation considered the most efficient energy-producing pathway?
It yields the highest ATP per glucose molecule
269
What is the theoretical maximum ATP yield from oxidative phosphorylation per glucose?
~28 ATP
270
How does ATP synthase adjust ATP production in response to energy demand?
Changes its rotation speed based on the proton gradient
271
What happens if ATP demand exceeds oxidative phosphorylation capacity?
Cells rely more on glycolysis and anaerobic metabolism
272
Why is oxidative phosphorylation essential for survival?
Provides most of the ATP needed for cellular function
273
What are the two types of photophosphorylation?
Cyclic and non-cyclic photophosphorylation
274
Where does photophosphorylation occur?
Thylakoid membrane of chloroplasts
275
What is the primary function of photophosphorylation?
To generate ATP and NADPH for the Calvin cycle
276
Which molecule is the initial electron donor in non-cyclic photophosphorylation?
Water (H2O)
277
What are the two photosystems involved in photophosphorylation?
Photosystem I (PSI) and Photosystem II (PSII)
278
What is the main function of Photosystem II?
Splits water to generate oxygen, protons, and electrons
279
What is the main function of Photosystem I?
Transfers electrons to NADP+ to form NADPH
280
What is the first step of photophosphorylation?
Photon absorption by chlorophyll in PSII
281
What is the second step of photophosphorylation?
Water splitting (photolysis) in PSII
282
What is the third step of photophosphorylation?
Electron transfer from PSII to plastoquinone (PQ)
283
What is the fourth step of photophosphorylation?
Electron transport through the cytochrome b6f complex
284
What is the fifth step of photophosphorylation?
Electron transfer to plastocyanin (PC)
285
What is the sixth step of photophosphorylation?
Photon absorption in PSI and electron transfer to ferredoxin (Fd)
286
What is the seventh step of photophosphorylation?
Electron transfer from ferredoxin to NADP+ reductase, producing NADPH
287
What is the eighth step of photophosphorylation?
Protons flow through ATP synthase to generate ATP
288
How is the proton gradient established during photophosphorylation?
Proton pumping by cytochrome b6f complex and water splitting in PSII
289
What is the function of plastoquinone (PQ) in photophosphorylation?
Transfers electrons from PSII to the cytochrome b6f complex
290
What is the function of the cytochrome b6f complex?
Transfers electrons and pumps protons into the thylakoid lumen
291
What is the function of plastocyanin (PC) in photophosphorylation?
Transfers electrons from cytochrome b6f to PSI
292
What is the function of ferredoxin (Fd) in photophosphorylation?
Transfers electrons from PSI to NADP+ reductase
293
How does ATP synthase generate ATP in photophosphorylation?
Protons flow down their gradient from the thylakoid lumen to the stroma
294
How does cyclic photophosphorylation differ from non-cyclic photophosphorylation?
Cyclic produces ATP only, while non-cyclic produces both ATP and NADPH
295
Which photosystem is used in cyclic photophosphorylation?
Only Photosystem I
296
Why is cyclic photophosphorylation necessary?
Balances the ATP/NADPH ratio for the Calvin cycle
297
What molecule acts as the final electron acceptor in non-cyclic photophosphorylation?
NADP+
298
What molecule acts as the final electron acceptor in cyclic photophosphorylation?
Plastoquinone (PQ), which recycles electrons back to PSI
299
What structural feature of the thylakoid membrane enhances photophosphorylation efficiency?
Stacked grana increase light absorption and reaction efficiency
300
How does the pH of the thylakoid lumen change during photophosphorylation?
Becomes more acidic due to proton accumulation
301
How does the pH of the stroma change during photophosphorylation?
Becomes more basic as protons move into the lumen
302
What happens if plastoquinone is inhibited in photophosphorylation?
Electron transport from PSII to cytochrome b6f is blocked
303
What happens if cytochrome b6f is inhibited in photophosphorylation?
Proton pumping and electron transfer to PSI stop
304
What happens if NADP+ reductase is inhibited in photophosphorylation?
NADPH is not produced, reducing Calvin cycle efficiency
305
What happens if ATP synthase is inhibited in photophosphorylation?
ATP production stops despite the presence of a proton gradient
306
What role do antenna pigments play in photophosphorylation?
Capture and transfer light energy to reaction centers
307
Why is chlorophyll a essential for photophosphorylation?
It directly participates in light-driven electron transfer
308
What is the absorption peak of Photosystem II (P680)?
680 nm (red light)
309
What is the absorption peak of Photosystem I (P700)?
700 nm (far-red light)
310
Why do plants have accessory pigments like carotenoids?
To extend the range of light absorption for photophosphorylation
311
How do light-harvesting complexes (LHCs) contribute to photophosphorylation?
Capture photons and transfer energy to the reaction center
312
What is the function of the oxygen-evolving complex (OEC) in Photosystem II?
Splits water into oxygen, protons, and electrons
313
How many photons are required to fully reduce one molecule of NADP+ in non-cyclic photophosphorylation?
Four photons
314
What is the ATP yield per electron transfer cycle in photophosphorylation?
Approximately 1.5 ATP
315
How do artificial electron acceptors affect photophosphorylation?
They disrupt normal electron flow and ATP/NADPH production
316
What happens to photophosphorylation when light intensity is too high?
Excess energy can damage reaction centers, leading to photoinhibition
317
What is photoinhibition in photophosphorylation?
Light-induced damage to PSII that reduces photosynthetic efficiency
318
How do plants protect against photoinhibition?
Use protective pigments and repair damaged PSII proteins
319
How does photophosphorylation regulate ATP and NADPH production based on cellular demand?
By switching between cyclic and non-cyclic electron flow
320
Why do desert plants rely more on cyclic photophosphorylation?
To produce ATP without excessive NADPH accumulation
321
How does photophosphorylation differ between C3, C4, and CAM plants?
C4 and CAM plants use additional ATP for carbon fixation under dry conditions
322
How does photophosphorylation contribute to photorespiration?
Oxygen produced can compete with CO2 in RuBisCO, reducing photosynthetic efficiency
323
How does photophosphorylation adapt to different wavelengths of light?
Different pigments optimize light absorption for varying light conditions
324
What is the impact of herbicides like DCMU on photophosphorylation?
Blocks electron transfer from PSII, stopping ATP and NADPH production
325
What is the role of ATP synthase in both photophosphorylation and oxidative phosphorylation?
Uses a proton gradient to drive ATP synthesis
326
How does photophosphorylation contribute to overall plant metabolism?
Provides ATP and NADPH for the Calvin cycle and biosynthetic pathways
327
How does photophosphorylation support plant growth?
Generates energy and reducing power for carbon fixation and biomass production
328
Why is photophosphorylation essential for global oxygen production?
It produces oxygen as a byproduct of water splitting in PSII
329
How does photophosphorylation relate to cellular respiration?
Provides the ATP and organic molecules that fuel mitochondrial respiration
330
What is the evolutionary significance of photophosphorylation?
Enabled the development of oxygenic photosynthesis and aerobic life
