Lecture 6 - Energy and Enzymes

What is energy?

The ability to do work or cause change

What is mass energy equivalence?

E=mc^2

What does mass-energy equivalence dictate?

Any object that has mass carries energy

What is a photon?

a particle of light

Doe photons have mass?

No

What is enthalpy?

Total heat content of a system.

What time of energy is enthalpy known as?

Internal/system energy

What Greek word does the word enthalpy come from?

Enthalpos

What is potential energy?

Stored energy due to location/chemical structures (chemical bonds, i.e. specific arrangement of atoms )

True or false: Only polar molecules participate in hydrogen bonding?

True

What is kinetic energy?

The energy an object has due to its motion

What is thermal energy?

Energy contained within a system that is responsible for its temperature

What is thermal energy a subset of?

Kinetic energy, due to particle movement and motion within a system

What is heat a flow of?

Thermal energy

What is the first law of thermodynamics?

Energy cannot be created or destroyed, only converted from one form to another

What does the first law of conservation of energy state?

Energy is CONSERVED

2Energy can TRANSFORM into different forms

What does the second law of thermodynamics state?

The entropy of a system and the surroundings will increase - energy will always become more spread out

What does energy spontaneously do?

Disperse from being localized to becoming spread out if it is not hindered from doing so

What is entropy?

The part of system energy that is associated with the system and unavailable for work

A measure of energy disposal

How does energy disperse?

Heat disperse → heat loss in a system

Energy becomes more spread out →

entropy increase ( in the system and surrounding)

When does entropy increase?

More in Volume (phase change)

2. More in Number (catabolic reaction)

3. More in molecular motion

What is Gibbs Free energy (G)?

The portion of a system's energy that is available to do work (convertible energy)

What does free energy perform?

The work of life

What is free energy determined by?

Enthalpy ((H, internal system energy) and entropy (S,

associated with a system)

What is the formula for Gibbs free energy?

ΔG = ΔH - T ΔS or G = H - TS

What does G stand for?

Convertible energy

What does H stand for?

System internal energy

What does TS stand for?

System associated energy (convertible)

What is the formula for change in free energy?

ΔG = G final state - G initial state OR ΔG = G in products - G in reactants

What are the descriptors of exergonic reactions?

Energy is released spontaneously

Higher free energy in reactants than product

ΔG < 0

What is an example of exergonic reactions?

ATP hydrolysis

What is ΔG at equilibrium?

When reactions in a closed system eventually reach equilibrium and can then do no work

What are the descriptors of endergonic reactions?

ENERGY required (put into the system)

System starts at a lower E state and ends at a higher E state

Not spontaneous

How do exergonic reactions happen in nature?

When coupled with endergonic reaction

What are redox reactions?

Reduction-oxidation reactions

Which reactions are energetically coupled?

Reduction-oxidation reactions

What do Reduction-oxidation reactions involve?

Electron transfers

What are descriptors of oxidation reactions?

Loss of electrons

Exergonic reactions

What are descriptors of reduction reactions?

Gain of electrons

Endergonic reactions

True or false: Oxidation and Reduction are two-half reactions, always occurring together

True