Molecules and Bioenergetics Flashcards
Lecture 3
What is the first law of thermodynamics?
Energy can be converted from one form to another, but can neither be created nor destroyed.
What is the second law of thermodynamics?
In the universe or an isolated system, the degree of disorder only increases.
What makes biological order possible?
the release of heat energy
Why is the release of heat energy necessary for cells to exist?
Cells are islands of order in a disorganized world. Biochemical processes that organize the cell simultaneously release heat, thereby increasing the universe’s level of disorder.
When is heat energy released from a cell?
during the interconversions of different types of energy
What is electric potential?
areas within a cell (or from inside and outside) where the charge in molecules is higher in one area and lower in the other; movement of charge across distances that allows work to be done
What is a concentration gradient?
area of a cell (or from the inside to the outside the cell) where there’s a high concentration of a molecule and somewhere else in the cell, the ion concentration is low; the movement of molecules across distances allows work to be done
Where is the potential energy for molecular work stored?
stored in chemical bonds, concentration gradients, and as electric potential
Why do chemical bonds release energy when broken?
Due to the rearrangement of the bonds and how the molecules interact with the surrounding environment, release energy
What does Gibbs Free Energy measure?
the energy of a molecule that could be used to do work in a cell
What are the four reasons molecules possess energy within their bonds?
vibration
rotation
translation (movement)
enthalpy
What is enthalpy?
energy stored in chemical bonds
What is the Gibbs Free Energy equation?
G=H-TS
where H = enthalpy; T=temperature in K; S = entropy
What is the change in Gibbs Free Energy equation?
Because many biological reactions result in a decrease in entropy, how does the cell ensure they occur?
Coupling exergonic to endergonic reactions
What does a -DeltaG indicate?
The reaction is exergonic and energetically favorable.
What does a +DeltaG indicate?
The reaction is endergonic and energetically unfavorable.
What’s the difference between an exergonic and an endergonic reaction?
In an exergonic reaction, the Gibbs free energy of the forward reaction decreases.
In an endergonic reaction, the Gibbs free energy of the forward reaction increases.
If a reaction has a negative DeltaG, a decrease in enthalpy and an increase in entropy, what will happen?
The reaction will occur.
How can I tell if coupling reactions will work?
If the additive DeltaG is negative.
How does ATP store energy?
There are 2 phosphoanhydride bonds between the phosphate groups. If the 2 phosphoanhydride bonds break, it causes the bonds between the phosphates to change and the two molecules interact with the environment differently, leading to an increase in entropy.
How does energy coupling work for potential chemical energy?
Energy is transferred to a reactant.
ATP and B react together, transferring phosphate to B, resulting in BP and ADP. Then, BP (high energy molecule) combines with C, resulting in D and inorganic phosphate.
How does energy coupling work for potential mechanical energy?
Energy-rich stressed states are created.
The phosphate group is transferred from ATP to another molecule, causing the other molecule to become stressed and leaving an ADP. When the phosphate group is cleaved off, the stressed molecule returns to it’s low energy state.
What is the equilibrium point?
the specific concentration of reagents in which there is the lowest amount of free energy within the system
What happens when a cell is at equilibrium?
Cell death. Cells require the input of energy to remain orderly. If no work gets done, the cell cannot survive.
How does a cell maintain a state of chemical disequilibrium?
Via intracellular steady-state concentrations maintained by equal rates of formation and consumption
Biomedical intermediates are consumed as soon as they are formed, leaving no opportunity for back reactions.
What is synthetic work?
process of photosynthesis
What is mechanical work?
use of energy to bring about a physical change in the position or orientation of a cell or some part of it
What is concentration work?
use of energy to transport ions or molecules across a membrane against an electrochemical or concentration gradient
What is electrical work?
use of energy to transport ions across a membrane against a potential gradient
