cellular respiration Flashcards
(55 cards)
What does the First Law of Thermodynamics state?
Energy cannot be created or destroyed, only transformed.
How does the First Law of Thermodynamics apply to living organisms?
Living organisms must obtain and convert external energy (from food or sunlight) to fuel biological processes.
What is the Second Law of Thermodynamics?
Energy transformations increase the overall entropy of the universe.
How do living systems maintain low entropy despite the Second Law of Thermodynamics?
By releasing heat and waste, increasing entropy in their environment while maintaining internal order.
Define an exergonic reaction.
A reaction that releases energy, such as cellular respiration.
What is a catabolic process? Give an example.
A catabolic process breaks down molecules to release energy, like breaking down glucose in cellular respiration.
What is an endergonic reaction?
A reaction that requires an input of energy to proceed, such as photosynthesis.
What is an anabolic process? Give an example.
An anabolic process builds complex molecules from simpler ones, like protein synthesis.
What does it mean for reactions to be ‘coupled’ in biological systems?
An exergonic reaction provides energy to drive an endergonic reaction.
Give an example of coupled reactions in cells.
ATP hydrolysis (exergonic) couples with muscle contraction or active transport (endergonic).
What role does ATP play in cellular work?
ATP releases energy through hydrolysis to power cellular activities like muscle contraction and active transport.
How does ATP release energy for cellular processes?
By breaking its high-energy phosphate bonds in an exergonic reaction.
What is Gibbs Free Energy (AG)?
AG measures the spontaneity of a reaction; negative AG indicates a spontaneous reaction.
How do we calculate AG in a reaction?
G = ДН - TAS, where AH is enthalpy change, T is temperature in Kelvin, and AS is entropy change.
If AG is positive, what does it mean for a reaction?
The reaction is non-spontaneous (endergonic) and requires energy input.
What does a negative AG indicate?
The reaction is spontaneous (exergonic) and releases energy.
What type of macromolecule are enzymes?
Enzymes are proteins.
What determines the shape of an enzyme?
The enzyme’s shape is determined by its amino acid sequence and how it folds into its tertiary structure.
What is the function of the enzyme’s active site?
The active site binds to substrates, facilitating the chemical reaction.
Describe the ‘lock and key’ model of enzyme function.
This model suggests that the enzyme’s active site perfectly fits the substrate, like a key fitting a lock.
What is the ‘induced fit’ model of enzyme function, and why is it more accurate?
This model proposes that the enzyme’s active site changes shape to bind more closely with the substrate, making it more accurate for how enzymes work.
What are enzyme ‘co-factors’? Give an example.
Co-factors are non-protein molecules that assist enzymes, such as zinc or magnesium ions.
How do enzymes accomplish biological catalysis?
Enzymes lower the activation energy of reactions, speeding them up without being consumed.
What is the difference between catalyzed and uncatalyzed reactions?
Catalyzed reactions proceed faster because enzymes lower the activation energy.
