138 Questions
What is the primary function of catabolism in metabolism?
Break down of complex molecules and release energy
Which molecules are produced in the cytosol during the breakdown of simple subunits?
Acetyl CoA, ATP, and NADH
In metabolism, what is the role of NADH as a molecule?
Energy carrier in glycolysis
Which of the following statements is true about glycolysis?
Regulated by the availability of glucose
What is the main product of fermentation of pyruvate?
Ethanol and Carbon Dioxide
Which molecule is the precursor for the production of ATP in glycolysis?
Glyceraldehyde-3-phosphate
What is the role of NADH in glycolysis?
Donates electrons and becomes oxidized
Which process leads to the regulation of glycolysis and gluconeogenesis?
Activation of feedback inhibition
What is the end product of the fermentation of pyruvate in anaerobic respiration?
Ethanol
Which statement best describes the energy output of metabolic pathways?
Some metabolic pathways generate more ATP than others due to differences in efficiency.
What are the precursors to ATP and to NADH?
ADP and NAD+
Is NADH a reduced or oxidized molecule?
Reduced
How is the NADH going to be used?
As a high-energy carrier of electrons
What does gluconeogenesis involve?
Synthesizing glucose from non-carbohydrate sources
Which statement is true regarding the energy output of glycolysis?
Glycolysis nets 2 ATP and 2 NADH
What happens to pyruvate in the absence of oxygen?
It is converted to lactate
Why is the regeneration of NAD important in glycolysis?
To continue glycolysis in the absence of oxygen
What is the primary reason for the increased gluconeogenesis in the livers of rats with incapacitated hind limbs?
Muscle atrophy
Which enzyme is not involved in gluconeogenesis according to the text?
Hexokinase
What would be the result if hind-limb mobility is restored in rats regarding gluconeogenesis?
Gluconeogenesis will decrease
Why do researchers observe synthesis of essential enzymes in rats with incapacitated hind limbs?
Increased energy demands
What conclusion did researchers draw from the observation of increased gluconeogenesis in rats with muscle atrophy?
Significantly increased gluconeogenesis in the liver
Where does the Energy Investment Phase of glycolysis occur?
Cytosol
What is the primary purpose of the Cleavage Phase in glycolysis?
To break down glucose
Which organelle is responsible for the Oxidation of Acetyl CoA and ATP Production in glycolysis?
Mitochondria
In which part of the cell does the Breakdown of Simple Subunits into Acetyl CoA and ATP occur?
Cytosol
What is the net outcome of the Energy Liberation Phase in glycolysis?
Generation of ATP
What is the starting molecule for glycolysis?
Glucose
What is the main difference between catabolism and anabolism in metabolism?
Catabolism releases energy, while anabolism requires an input of energy.
During a redox reaction, what does reduction of a molecule involve?
Gain of electrons by a molecule.
Why does controlled oxidation benefit a cell more than simple burning of a molecule?
Controlled oxidation allows for gradual release of energy and prevents damage to the cell.
In a redox reaction, what often accompanies the pickup of an electron by a molecule?
Proton (H+)
What does cellular respiration primarily aim to generate from the breakdown of organic molecules?
ATP
How would you differentiate between metabolism and cellular respiration?
Metabolism covers all chemical reactions in an organism, while cellular respiration specifically refers to ATP generation.
What is the end product of Alcohol Fermentation?
Ethanol
How many ATP molecules are produced per glucose molecule in Lactic Acid Fermentation?
2
What is the primary function of Dehydrogenase in cellular metabolism?
Removes hydrogen ions and electrons
Which phase of glycolysis generates ATP and NADH?
Energy Liberation Phase
What does Substrate Level Phosphorylation involve?
Transfer of a phosphate group directly to ADP from a substrate molecule
Where does the process of pyruvate oxidation occur in a cell?
Matrix
What is the fate of the NADH and FADH2 produced during pyruvate oxidation?
They proceed to the electron transport chain (ETC).
What happens to the 2CO2 released during pyruvate oxidation?
It does not participate in any further metabolic reactions.
Which part of the mitochondria invaginates into cristae?
Inner membrane
What is the primary function of ATP synthase in aerobic respiration?
Producing ATP from ADP using the energy gradient established during ETC
Where does the majority of biochemistry occur in relation to the mitochondria structure?
Matrix
Which component of the citric acid cycle leads to the production of ATP directly?
ATP synthase
What is the primary function of the inner mitochondrial membrane's specific transporters?
e- transport components
Which molecule is NOT produced during the pyruvate oxidation process?
Oxygen
What is the fate of the 3 NADH molecules produced during pyruvate oxidation?
Go to ETC
Where does the conversion of pyruvate into acetyl CoA occur during aerobic respiration?
Mitochondrial matrix
Which enzyme complex is responsible for converting pyruvate into acetyl CoA?
Pyruvate dehydrogenase complex
What molecule does acetyl CoA bind to when it enters the citric acid cycle?
Oxaloacetate
How many reactions occur in the citric acid cycle?
8
Which molecule must be re-generated for the citric acid cycle to continue?
NAD+
What is one of the products of pyruvate decarboxylation?
CO2
In which cellular organelle does the citric acid cycle take place?
Mitochondrion
How many ATP are produced per glucose molecule during the process of glycolysis and the TCA cycle combined?
6 ATP
Which of the following statements correctly describes the redox pair NADH and NAD+?
NADH is oxidized to NAD+
Which molecule below undergoes reduction during cellular respiration?
Oxygen (O2)
Is FADH2 a reduced or oxidized molecule in the context of the electron transport chain?
Reduced
What happens to the redox potential of the Electron Transport Chain (ETC) components as electrons move through the chain?
Increases
Which of the following molecules is a better electron donor in cellular respiration?
FADH2
How many high-energy electrons does FADH2 bring to the Electron Transport Chain (ETC)?
2
Proton motive force is primarily a result of what during cellular respiration?
ATP synthesis
What is the function of cytochromes in the Electron Transport Chain (ETC)?
Hold more tightly to electrons
What is the primary reason why the citric acid cycle stops almost immediately upon removal of oxygen?
Oxygen is needed for the regeneration of molecules crucial for the cycle to continue.
What would occur if the proton motive force in the electron transport chain were reversed?
ATP synthase would hydrolyze ATP instead of synthesizing it.
How is pyruvate transported into the mitochondrial matrix?
Active Transport
What is the primary role of NADH and FADH2 in cellular respiration?
Supply electrons to the electron transport chain.
Why do researchers observe a cessation of the citric acid cycle upon removal of oxygen?
Oxygen is necessary for the synthesis of NAD+ and FAD.
Which component in cellular respiration directly uses oxygen as a reactant?
Electron Transport Chain
What happens if ATP synthase functions in reverse during oxidative phosphorylation?
ATP hydrolyzes into ADP releasing energy.
What type of transport mechanism moves ATP into the intermembrane space?
Active Transport
How does the absence of oxygen impact the synthesis of ATP in the citric acid cycle?
Reduces the number of ATP molecules produced
Where is the electron transport chain located?
Inner mitochondrial membrane
What is the function of cytochromes in the electron transport chain?
Accept and donate electrons
What is the final electron acceptor in the electron transport chain?
Water
What is the role of ATP synthase in cellular respiration?
Produce ATP from proton motive force
What is the primary role of NADH and FADH2 in cellular respiration?
Electron donation
Which molecules shuttle electrons between Complex III and Complex IV in the electron transport chain?
Ubiquinone (Q); cytochrome c
What is the primary role of chemiosmotic coupling in cellular respiration?
Driving ATP synthesis
Which region of the mitochondrion plays a key role in the electron transport chain and ATP synthesis?
Inner mitochondrial membrane
From which metabolic processes do high-energy electrons for ATP production primarily originate?
Citric acid cycle and fatty acid oxidation
What is the number of electrons donated by FADH2 for ATP production in cellular respiration?
Two electrons
Before donating their electrons, are NADH and FADH oxidized or reduced?
Oxidized
Which cellular component contains the proteins involved in the electron transport chain in a mitochondrion?
Intermembrane space
Where is ATP synthase located within the mitochondria?
Inner mitochondrial membrane
What is the primary function of the F0 subunit within ATP synthase?
Proton translocation
What drives the rotation of the rotor within ATP synthase?
Proton flow
What is a redox pair in cellular metabolism?
An electron donor and acceptor
What does redox potential measure?
Electron donation tendency
How do protons contribute to ATP synthesis in mitochondria?
Creating a pH gradient
Where are the protons moved to during photosynthesis?
Thylakoid lumen
What provides the energy to move protons in the process of photosynthesis?
Electron transport chain
How is the energy of the proton motive force used in photosynthesis?
To drive ATP synthesis
Which enzyme is responsible for replacing the electrons that leave the reaction center of Photosystem II?
Photosystem I
During photosynthesis, where do the energized electrons leaving Photosystem II go next?
Cytochrome b6f
What is the fate of the oxygen produced during photosynthesis?
Released as a byproduct
Where in the chloroplast does the Calvin Cycle occur?
Stroma
What is the primary function of the thylakoid membrane in a chloroplast?
e- transport components
What is the significance of the RuBisCO enzyme in photosynthesis?
Converts RuBP and CO2 to 3PGA
What is the primary purpose of the cyclic photophosphorylation process in photosynthesis?
Only ATP production in photosystem I
What happens when O2 is fixed instead of CO2 during photosynthesis?
Initiation of photorespiration
In C4 plants, what is the purpose of separating steps into different locations using PEP and PEP carboxylase?
To reduce photorespiration
What happens to the energized electrons as they leave Photosystem I?
They are transferred to an electron carrier called ferredoxin (Fd)
What is the primary purpose of the ATP and NADPH produced by the light reactions in photosynthesis?
To drive the Calvin cycle
True or False: The Calvin cycle occurs in the thylakoid space.
False
What is produced instead of 3-phosphoglycerate when O2 is fixed during photorespiration?
Phosphoglycolate and 3-phosphoglycerate
What is the primary function of the triosephosphates produced during photosynthesis?
Produce glucose
Which of the following mechanisms have some plants evolved to avoid photorespiration?
C4 and CAM photosynthesis
Do all plant cells perform photosynthesis?
No, only some plant cells perform photosynthesis
Do all plant cells undergo cellular respiration?
Yes, all plant cells undergo cellular respiration
What is the primary purpose of light-dependent reactions in photosynthesis?
Generate ATP and NADPH
Where do light-independent reactions (Calvin Cycle) take place in a chloroplast?
Stroma
When chlorophyll absorbs light energy, what happens to its electrons?
They become excited and enter a higher energy state
What is the main function of the thylakoid membranes in a chloroplast during photosynthesis?
Generate ATP and NADPH
Where are photosystems located within the chloroplast?
Thylakoid membranes
Which organelle is responsible for converting light energy into chemical energy in photosynthesis?
Chloroplast
In what order do Photosystem II and Photosystem I function in the electron transport chain?
Photosystem II before Photosystem I
What is the outcome of the light-independent reactions in photosynthesis?
Conversion of carbon dioxide to glucose
What is the primary function of a proton motive force generated by Photosystems II and I?
Drive ATP synthesis
Where do the excited electrons in Photosystem II end up after passing through the electron transport chain?
Generating ATP
What is the fate of the electrons from Photosystem I after being used to reduce NADP+ to NADPH?
Form ATP
How is oxygen generated by photosynthesis?
As a byproduct of the electron transport chain
How are the excited electrons that leave Photosystem II replaced?
By the splitting of water molecules
Where does the Calvin Cycle occur?
In the stroma of chloroplasts
What enzyme is responsible for the carbon fixation reaction?
Rubisco
What is produced when Rubisco combines RuBP and O2?
Photorespiration
What types of plants are C4 plants?
Plants with a specialized method of carbon fixation
How do C4 plants avoid photorespiration?
By separating initial CO2 capture from the Calvin Cycle
What happens to the sugars produced by carbon fixation?
Stored as starch for later use or utilized for energy by the plant
What impact would the genetic mutation eliminating cristae from the mitochondria have on the energy production of round worms?
Decrease energy production due to reduced surface area for reactions
How would the lack of cristae in the mitochondria affect the overall size and function of mutated yeast cells?
Decrease size and function
Why does the citric acid cycle stop almost immediately upon removal of oxygen?
Oxygen is required for electron carrier production
Why was DNP used as a drug to help patients lose weight?
It uncouples electron flow from ATP synthesis
Why would DNP as a weight loss drug be considered dangerous?
It disrupts normal metabolic processes
How does the lack of cristae in mitochondria impact the efficiency of cellular respiration?
Decreases efficiency by reducing surface area for reactions
What role does oxygen play in the electron carrier production related to the citric acid cycle?
Enables electron carriers to accept and donate electrons
Learn about the 3 stages of food molecule breakdown in metabolism: digestion in the GI tract, breakdown into simple subunits, and oxidation of Acetyl CoA for ATP production. These processes are essential for energy release in the body. Extracted from 'Essential Cell Biology, Fifth Edition'.
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