Thermodynamics
Define metabolism, catabolism, and anabolism
Metabolism is the sum of all chemical reactions that occur within a living organism to maintain life.
Catabolism is the breakdown of complex molecules into simpler ones, releasing energy.
Anabolism is the building of complex molecules from simpler ones, which requires energy.
What is the purpose of an enzyme in a chemical reaction?
Speeds up a reaction
List the inputs and outputs for glycolysis.
Inputs: 1 glucose
Outputs: 2 pyruvate
List the inputs and outputs of light reactions.
Inputs: light, 12 H2O, 18 ADP + Pi, 12 NADP+
Outputs: 6 O2, 6 H2O, 18 ATP, 12 NADPH
What does it mean when something is being reduced?
Gaining electrons
Define endergonic and exergonic
An endergonic reaction is a chemical reaction that requires energy input to proceed.
An exergonic reaction is a chemical reaction that releases energy to its surroundings.
What effect do enzymes have on the change in free energy (ΔG) of a chemical reaction?
Enzymes have no effect on the change in free energy of a chemical reaction.
List the inputs and outputs of pyruvate oxidation.
Inputs: 2 pyruvate
Outputs: 2 Acetyl-Coa
List the inputs and outputs of the calvin cycle.
Inputs: 6 CO2, 18 ATP, 12 NADPH
Outputs: 2 G3P, 18 ADP + Pi, 12 NAD+
What does it mean when something is being oxidized?
Losing electrons
Do you think transcription is an endergonic or exergonic process? Why? What about translation?
Transcription= endergonic
During transcription, nucleotides are joined together to form a long RNA chain. This involves the formation of phosphodiester bonds, which is a non-spontaneous, energy-consuming process
Translation= endergonic
It involves the formation of peptide bonds between amino acids, which is a non-spontaneous process
What effect do enzymes have on the activation energy (EA) of a chemical reaction?
Enzymes help lower the activation energy of the reaction. Enzymes can do this because they help the reactants to achieve their unstable transition state
that is required for them to be converted into products.
List the inputs and outputs for citric acid cycle.
Outputs: 4 CO2
List the inputs and outputs of photosynthesis as a whole.
Inputs: light, 6 CO2, 12 H2O
Outputs: 2 G3P, 6 O2, 6 H2O
What is oxidized and what is reduced in the electron transport chain?
NADH and FADH₂ are oxidized, donating their electrons to the ETC. Oxygen is reduced to form H₂O (final electron acceptor)
Can you think of an example of dehydration synthesis in transcription?
Transcription: formation of phosphodiester bonds. Each time a new nucleotide is added to the growing RNA strand, a phosphodiester bond forms between the 3′ hydroxyl group of the last nucleotide and the 5′ phosphate of the incoming one. This reaction releases a water molecule – making it a dehydration synthesis reaction.
Why would a cell want to control what can get inside it (and what can’t) and what can get out of it (and what can’t)?
Cells are open systems in which molecules can move in and out. Cells need to be open systems so that fuel and nutrients can continuously flow in, and waste products can continuously flow out. This constant flow keeps metabolic reactions very far from equilibrium. If equilibrium was reached for any metabolic reaction, the cell would no longer be able to do any work, and the cell would die.
List the inputs and outputs of the electron transport chain.
Inputs: 10 NADH, 2 FADH2, O2, H+
Outputs: H2O
How is energy coupling used for light reactions and the calvin cycle?
Overall the light reactions can be considered to be exergonic, using light energy to produce ATP. The Calvin Cycle is endergonic, consuming the ATP produced in the light reactions
What is oxidized and what is reduced during light reactions?
Oxidized: Water molecules are split in the photosystem II complex, producing oxygen (O₂), protons (H⁺), and electrons (e⁻)
Reduced: Electrons from the light reactions are passed along the electron transport chain (ETC), and NADP⁺ gains electrons and a proton (H⁺) to form NADPH
Is pumping of H+ in the proton motive force an exergonic or endergonic reaction? Why?
Endergonic because it required energy to move protons against the gradient (going against the concentration gradient)
List the four types of transports and a short description of them.
Passive diffusion: Movement of molecules directly through the membrane from high to low concentration, without energy or transport proteins
Facilitated diffusion: Movement of molecules from high to low concentration through a protein channel or carrier, without energy
Active transport: Movement of molecules against their concentration gradient (low to high) using energy (usually ATP) and transport proteins
Co-transport: Movement of one substance with its gradient to drive the active transport of another substance against its gradient, using a shared transport protein
List the inputs and outputs of chemiosmosis.
Inputs: H+ from the proton motive force, ADP, Pi
Outputs: ATP
How is energy coupling used for electron transport chain and electron transport chain.
Electrons flow from high potential energy to low potential energy through the electron transport chain, releasing energy (exergonic). This energy is then used (endergonic) to pump H+ from the stroma to the inner thylakoid space. H+ is traveling up its concentration
gradient, from low concentration to high concentration.
What is oxidized and what is reduced during the calvin cycle?
Oxidized: NADPH --> NADP+
Reduced: 3-PGA --> G3P