Thermodynamics & Energy
Which statement about energy-releasing (exergonic) reactions is true?
They happen naturally (spontaneously) and release energy
What is the "activation energy" of a chemical reaction?
the small spark of energy needed to break initial bonds and get a reaction started
Which molecule is referred to as "The Universal Currency of Cellular Work"?
ATP
How many total CO2 molecules are released from the complete oxidation of one original glucose molecule across pyruvate oxidation and the Citric Acid Cycle combined?
6 CO2
How do uncoupling membrane channels in brown fat tissue alter energy transformation during winter hibernation?
They allow H+ protons to flow back into the matrix without passing through ATP Synthase, dissipating stored energy as heat.
What happens if a living cell reaches chemical equilibrium?
It stops functioning and dies
Which type of metabolic pathway builds large, complex molecules from small building blocks and requires energy input?
Anabolic pathway
In an animal cell (like a red blood cell), what happens when it is placed in a hypotonic solution?
It lyses (bursts
What structural change happens to an enzyme during denaturation caused by extreme temperature or pH deviations?
Secondary and tertiary protein structures are disrupted, leading to a loss of catalytic ability
What directly powers the mechanical rotation and catalytic conformational changes of ATP Synthase during chemiosmosis?
The proton-motive force generated by H+ protons diffusing down their electrochemical gradient into the matrix
Why does ATP store so much energy in its tail?
The negative charges on the phosphate groups push against each other
what does "energy coupling" mean in a cell?
Using energy released from an exergonic reaction to power an endergonic reaction
Which part of cellular respiration does NOT need oxygen?
Glycolysis
What type of proteins in the electron transport chain contain iron and possess progressively higher electronegativity down the pathway?
Cytochromes
Starting with ONE molecule of glucose, what is the combined yield of electron carriers produced ONLY during Pyruvate Oxidation and the Citric Acid Cycle (excluding Glycolysis)?
How do enzymes speed up chemical reactions?
By lowering the starting energy (activation energy) needed
According to the First Law of Thermodynamics, energy can be:
transferred or transformed, but never created or destroyed
According to the Second Law of Thermodynamics, what effect does every energy transfer or transformation have on the universe?
It increases the total entropy of the universe
How many ATP molecules are directly generated by substrate-level phosphorylation across the entire process of cellular respiration (Glycolysis + Citric Acid Cycle)?
4 ATP
On an enzyme kinetics graph measuring reaction velocity against substrate concentration, how does adding a noncompetitive inhibitor affect the system?
It binds to an allosteric site and changes the enzyme's shape, preventing high substrate concentrations from fully restoring maximum velocity
How can a cell stop a "competitive inhibitor" from blocking an enzyme?
By adding a lot more substrate (the reactant)
In a redox reaction, what happens during "oxidation"?
A molecule loses electrons
What is the specific term for a non-protein organic cofactor, often derived from vitamins, that an enzyme needs to function?
Coenzyme
What occurs during the two steps of alcohol fermentation in anaerobic conditions?
Pyruvate is decarboxylated to acetaldehyde and then reduced by NADH to ethanol
During pyruvate oxidation, what essential vitamin derivative is attached to the 2 carbon fragment to produce the high-potential-energy compound Acetyl CoA?
Vitamin B