4.1 - Metabolism overview: Energy and chemical reactions Flashcards
What is the role of the enthalpic (ΔH) and entropic (ΔS) factors in the Gibbs Free Energy (ΔG) equation?
ΔG = ΔH – TΔS
A negative value for ΔH and a positive value for ΔS both contribute toward achieving a negative value for ΔG and a spontaneous reaction.
When ΔG<0, there is a thermodynamic driving force for the reaction or process in the forward direction. When ΔG>0, then reactants are favored instead. When ΔG=0 the system is at equilibrium.
What is the difference between anabolic and catabolic reactions?
Catabolic reactions break down larger molecules, such as carbohydrates, lipids, and proteins into their constituent smaller parts.
Anabolic reactions synthesize larger molecules from smaller constituent parts, using ATP as the energy source.
Where do anabolic and catabolic reactions occur?
Anabolism and catabolism occur simultaneously in the cell with different rates, since the rates of their chemical reactions are controlled independently of each other.
What’s the difference between Chemotroph and Phototroph?
Phototrophs consume sunlight as the source of energy to undergo photosynthesis.
Chemotrophs use chemical reactions and undergo chemosynthesis to get energy.
How do the high energy phosphate bonds of ATP make it a good energy carrier in anabolic polymerization reactions of a nucleic acid strand?
These bonds are high energy carriers because of the associated electronegative charges exerting a repelling force between the phosphate groups.
Enzymes make the ∆G of the reaction negative to speed up the reaction. (T/F)
False
What are the steps for enzyme catalysis? (for interest only)
Intiation, transition state stabilization, termination.
What is the transition state?
A high-energy, unstable state, and some amount of the activation energy must be added in order for the molecule reach it. Because the transition state is unstable, reactant molecules don’t stay there long, but quickly proceed to the next step of the chemical reaction.
What happen during initiation?
Enzyme loosely binds to substrate in a specific orientation in the active sites, forming an enzyme substrate complex and bringing the substrates closer together.
What happen during transition state stabilization?
The active site is clearly complementary to the transition state for the reaction, stabilizing it more than the substrate, so reducing the barrier to reaction.
What happen during termination?
Products released from active site with enzyme unchanged.
