Metabolism Flashcards
Define thermodynamics
Deals with the transformation of energy in all forms.
What is energy
Energy is the ability to do work
What forms does energy exist in
Heat (wasted) mechanical, chemical (main focus) and radiant
First law of thermodynamics
Energy is not created or destroyed it is rearranged (photosynthesis)
Or
The total amount of energy in any closed system is constant. Energy can’t be created or destroyed it can only be converted from one form to another. If a physical system gains an amount of energy another physical system must experience a loss of energy of the same amount
What is the primary source of energy in living systems?
Chemical energy
Conversion of energy depends on…
The breaking and forming of chemical bonds in a chemical reaction
Define bond energy
Measure of stability of a covalent bond between atoms and is measured in KJ. The amount of energy required to break one mole of bonds between two atoms and is also equal to the amount of energy released when that bond is formed
Energy absorbed vs released
Energy is absorbed when reactant bonds break
Energy is released when product bonds form
Define activation energy
The amount of energy required to break the reactant bonds
Activation energy is…
Equal to the difference between potential energy level of the transition state and the potential energy of the reactants
Define transition state
Temporary condition which bonds within reactants are breaking and bonds between products are forming (reached if activation energy is provided)
Define exothermic
If a chemical reaction releases more heat than it uses
Define endothermic
If more heat enters the system in a chemical reaction than is actually released at the end in of the reaction
The overall change in energy that occurs in a chemical reaction is called….
Heat or enthalpy of a reaction and is symbolized by delta H
Values of delta H
If it’s positive the reaction is endothermic
If it’s negative the reaction is exothermic
How to calculate enthalpy
Calculate bond energies for all bonds using chart of values (reactants are positive, products are negative)
Find the sum of reactants + (-products) answer depends on delta H value
What is the second law of thermodynamics?
In every energy transfer or conversion some of the useful energy in the system becomes unstable and increases the entropy of the universe
What is entropy? (Delta S)
Degree of disorder or randomness (during any transformations, energy tends to become increasingly unavailable for useful work (cleaning room makes entropy decrease in room and increase in the body)
Values of entropy
+ means increased disorder
- means decreased disorder
Kelvin scale
Based on the kinetic energy of molecules
Since it’s an absolute scale it doesn’t have degrees
At 0 kinetic energy 0 K is -273•C
Define spontaneous change
Spontaneous change or reaction is one that will continue to occur on its own once it’s underway until completion with out the continual input of energy (once you burn a piece of paper it keeps burning but it also doesn’t start to burn on its own)
Define free energy
Energy that can do useful work (also called Gibbs free energy)
Organisms use this to power their cells
Quantity of free energy available in a system is symbolized by the letter G
Values of free energy
+ G means more free energy in products than reactants so reaction is spontaneous (they must have obtained the energy from an external source)
- G means more free energy in reaction than products, so reaction isn’t spontaneous (energy released can be used to do work in other reactions)
What is a coupling reaction?
The transfer of energy from one reaction to another in order to drive the second reaction
