3.1 Metabolism & Energy Flashcards
Metabolism
The sum of all chemical rxns in a cell or organism
Kinetic energy
The energy of motion
Potential energy
The stored energy that an object possesses as a result of its position relative to other subjects or to its internal structure
1st Law of Thermodynamics
Principle that states that energy can be transferred or transformed, but it can’t be created or destroyed
Bond energy
The minimum amount of energy that’s required to break a particular type of bond: measured in KJ/mol of bonds
Exothermic rxn
A chem. rxn in which energy is released, leaving the products with less chemical potential energy that the reactants
Activation energy, Ea
The minimum amount of energy that chemical reactants must absorb to start a rxn
Transition state
A temporary condition during a chemical rxn in which the bonds in the reactants are breaking and the bonds in the products are forming
Mole
6.02x10^23 atoms or molecules
Endothermic rxn
A chem. rxn in which energy is absorbed, giving the products more chemical potential energy that the reactants.
2nd Law of Thermodynamics
Principle that states that every time energy is converted to another form, some of the energy becomes unusable
Entropy
A measurement of disorder in a system
Spontaneous change
A change that will, once begun, continue on its own under a given set of conditions: does not require a continuous supply of energy.
Free energy
Energy that can do useful work: also called Gibbs free energy
Exergonic rxn
A chemical rxn that releases free energy; the products have less free energy that the reactants
Endergonic rxn
A chemical rxn that absorbs free energy: the products have more free energy that the reactants
Anabolic pathway
A pathway in which energy is supplied to build complex molecules from simple molecules
Energy coupling
The transfer of energy from 1 rxn to another in order to drive the second rxn
Catabolic pathway
A pathway in which energy is released and complex molecules are broken down into simple molecules
Anabolic pathway
A pathway in which energy is supplied to build complex molecules from simple molecules
Energy
Ability to do work
Living organisms must
Capture, store, and use energy
Metabolism:
The sum of the chemical rxns taking place, sums up anabolic and catabolic rxns
Potential energy EX.
- Gravitational
- Chemical
1st Law of Thermodynamics
“Law of energy conservation”
- Energy can’t be created or destroyed; it can only be changed from one form to another
Examples of first law of thermodynamics
For example:
1) Light energy comes from the sun
2) Converted to chemical energy by green plants
3) Stored in plant cells as carbs
4) Passed on to other organisms when they eat the plants
5) Converted to other forms: mechanical, thermal, sound…
Energy conversion depends on
breaking and reforming chemical bonds
Electrons have more P.E the farther
they are from the nucleus
Electrons can be attracted
the multiple nuclei at the same time = chemical bond
Bonds to break energy is
ABSORBED, so it can be used to pull away an electron
New bonds form energy is
RELEASED
Every rxn requires energy to
BEGIN the rxn, even it ultimately produces energy ; called activation energy; Ea
Intermediate state; when bonds are broken and new ones are ready to be formed, known as the
TRANSITION STATE
Exothermic rxn:
Net release of energy
Endothermic rxn:
Net absorption of energy
2nd law of thermodynamics
Every time energy is converted to
another form, some of the useful energy
becomes unusable and increases the
entropy of the universe
Entropy refers to
the degree of disorder in a
system
All systems in the universe tend towards
entropy
Entropy also increases when # product
molecules
> # reactant molecules
Living cells can create order by expending
energy
Entropy of their surroundings increases
Spontaneous Changes
One that will continue to occur
on its own once it
has started
E.g. a match will continue to burn once it’s started; a
diver will continue to fall once they have jumped
Gibbs Free Energy
Since rxns aren’t 100% efficient,
whatever energy
remains to do work is known as free energy
Non-spontaneous requires
continual energy input
E.g. keeping a pot of water boiling
Need to look at
energy changes, entropy, and
temperature
ΔG = Gfinal – Ginitial
If ΔG is negative, energy is released (exergonic) 🡪
spontaneous
If ΔG is positive, energy is absorbed
Coupled Reactions
Cells continuously carry out thousands of rxns
Exergonic rxns release free energy, which can be
used to make endergonic rxns happen
Combined, the rxns have – ΔG, so they occur spontaneously
Rxns tend to be part of a
a metabolic pathway
Catabolic:
Complex molecules broken down,
releasing energy (e.g. cellular respiration) ΔG -ve
Anabolic:
simple molecules combined, consuming
energy (e.g. photosynthesis) ΔG +ve
All living things perform activities that
increase the free energy available
- Movement, growth, repair, reproduction
(Continual energy supply is required)
This energy comes from
ATP
