Energy and Enzymes
What are the 1st and 2nd Laws of Thermodynamics?
1st: Energy cannot be created nor destroyed, only transformed.
2nd: The entropy (disorder) in the universe is always increasing.
What is ΔG for an exergonic or an endergonic reaction?
Negative for exergonic, positive for endergonic.
What is the function of NADH and FADH2?
They are electron carriers.
How are Cellular Respiration and Photosynthesis related?
The products of one process are the reactants of the other.
Where is chlorophyll located in plants? Why?
In the thylakoid membrane, since that is where the Light Reactions take place.
What gives enzymes their specificity?
The structure of their active site is specific to their substrate.
Why are the Citric Acid Cycle and the Calvin Cycle, cycles?
Because they regenerate their starting molecules (either oxaloacetate or RuBP).
Where do each of the stages of Cellular Respiration take place?
Glycolysis: Cytosol.
Pyruvate Oxidation: Mitochondrial Matrix.
Citric Acid Cycle: Mitochondrial Matrix.
Oxidative Phosphorylation: Inner Mitochondrial Membrane.
What are Gibbs Free Energy and Entropy?
Gibbs Free Energy is the energy available to do work.
Entropy is the level of disorder in a system.
What is the function of Rubisco?
Carbon fixation.
How do enzymes catalyze chemical reactions?
By lowering the activation energy of the reaction.
Substrate level phosphorylation for Glycolysis and the Citric Acid Cycle. Chemiosmosis for Oxidative Phosphorylation and Light Reactions.
What happens to electrons as they move through the Electron Transport Chain?
They lose energy.
Give an example for an anabolic and a catabolic reaction.
Anabolic: Photosynthesis.
Catabolic: Cellular Respiration.
What are the inputs for the Light Reactions and the Calvin Cycle?
Light Reactions: Light and H2O.
Calvin Cycle: ATP, NADPH, and CO2.
Are the amino acids that make up the active site of an enzyme always next to each other? Why or why not?
No. They can be in different parts of the polypeptide chain, but come together once the protein folds.
Why are a lot of plants green?
Because chlorophyll, their main pigment, does not absorb green light.
Why do you need ATP during glycolysis? (2 reasons)
- Trap glucose inside the cell.
How does ATP drive endergonic reactions?
The hydrolysis of ATP is really exergonic, which usually gives enough energy to overcome endergonic reactions.
How many times does the Calvin Cycle need to occur to synthesize 1 molecule of glucose? Why?
6 times, since each CO2 molecule provides 1 carbon atom.
Define competitive, non-competitive/allosteric, irreversible, and feedback inhibition of enzymes.
Competitive: Inhibitor binds to the active site.
Non-Competitive: Inhibitor binds to the allosteric site.
Irreversible: Inhibitor binds covalently to the active site.
Feedback: The product of a reaction inhibits the enzyme that catalyzes it.
Why are oxygen and water needed in Cellular Respiration and Photosynthesis respectively?
They are the terminal electron acceptor and electron donor respectively.
Explain chemiosmosis. How is ATP produced during Oxidative Phosphorylation?
NADH and FADH2 transfer high-energy electrons to the Electron Transport Chain. There, protein complexes pump H+ to the intermembrane space to create an electrochemical gradient. ATP synthase is able to use this gradient as energy to synthesize ATP.
What are most carbons in the G3P molecules synthesized during the Calvin Cycle used for?
Regenerate RuBP.
What are the functions of Photosystem II and Photosystem I?
Photosystem II: Excites electron with energy from light and oxidizes H2O.
Photosystem I: Further excites the electron and synthesizes NADPH.