energetics and enzymes Flashcards
Sugars and fats have many nonpolar C-C and C-H bonds, where the negative charges on electrons are relatively far from the positive charges in the C and H atoms. This means that they have high _______.
potential energy
The electrons in C-O and H-O bonds are held tightly by oxygen atoms (due to electronegativity differences), meaning that they now have
low potential energy
What is free energy?
product of the amount of entropy (the degree of disorder) and the amount of thermal and potential energy in the ions and molecules involved.
If a chemical reaction leads to lower potential potential energy when products are compared to reactants, (requires less energy to maintain it) it is more likely to be
spontaneous
if a chemical reaction leads to an increase in entropy when products are compared to reactants, (meaning that the products are more disordered) then it is more likely to be
spontaneous
Spontaneous reactions are (exergonic/enderonic) while non-spontaneous reactions are (exergonic/enderonic)
ex, end
Chemical energy
potential energy available in a molecule
Reaction Coupling
reactions are coupled to phosphorylation by ATP to make them exergonic overall
Energetic coupling
a phosphorylation reaction that makes a nonspontaneous reaction spontaneous because it raises the free energy of the reactants
What reaction is most commonly used to drive unfavorable reactions in the cell
ATP hydrolysis to ADP+Pi
does whether or not a reaction is favorable or not, tell us anything about how fast the reaction will go?
no
As old bonds break and before new bonds form, there is an intermediate condition called
transition state
In the transition state, the reacting substances are less ______than they were before the reaction started, thus their free energy _____.
less stable, spikes
Size of spike is called
activation energy
Spatial orientation of reactants
-Reactants need to collide in precise orientations in order for chemical reactions to occur
-Unlikely event
High activation energy
The intermediate transition state in a reaction is unstable and has a high free energy
Many spontaneous reactions occur very slowly due to…
- Spatial orientation of reactants
-High activation energy
What are biological catalysts that solve the spatial orientation and activation energy problems?
enzymes
How does a cell increase the probability that enzymes will encounter their substrates?
Compartmentalization of enzymes and substrates
- can speed up reactions limited by the speed of diffusion by a factor of 10
- occurs in the endoplasmic reticulum, cell nucleus, Golgi apparatus, peroxisome, etc.
Enzymes have high specificity towards their substrates and work best under specific environmental conditions (true/false)
true
