Break down processes

ie: breaking bonds of large molecule to yield smaller ones

*energy released

Synthesize/join smaller molecules

*energy required

ie: photosynthesis 

energy that matter possesses due to structure of location

ie: potential energy in chemical bonds

Thermodynamics

You don't talk about thermodynamics....

Energy can neither be created nor destroyed

*it can be converted to other forms (heat is difficult and is often lost and not recovered to do work)

2nd Law of Thermodynamics

You don't talk about thermodynamics!

As energy conversions occur, entropy is always increasing

If system (cell) is ordered, surroundings (universe) is disordered

Change in free energy

G Final - G Initial

Energy is released

ie: Diver

A spontaneous reaction, not necessarily fast, but no energy input is required

Δ G is Negative 

Requires energy

ie: joining smaller molecules

NOT spontaneous

Requires Energy

ΔG is greater than or equal to zero

Adenosine Triphosphate

hydrolysis of ATP can be used to drive cellular work

ATP  ---> Pi (unused phosphate) + ADP + Energy

Energy from exergonic reactions supplied to endergonic reaction

one positive ΔG (endergonic)

one negative ΔG (exergonic)

1.) Both reactions must share a common intermediate

i.) A + B ----> C

ii.) C   -----> D + E

(both have C)

2.) Net ΔG must still be negative (exergonic must be larger) 

Proteins that catalyze (speed up) chemical reactions

*end with "ase"

ie: sucrase = enzyme for sucrose

Show specificity for it's reactants (substrate)

Speeds up reactions by lowering the energy of activation

Involved in lowering Ea

• orients substrates correctly
• strains substrate bonds
• creates favorable microenvironment (pH, temp, salt)
• temporarily bonds to substrate 
• Not used up (can reuse enzyme)
• ΔG is unaffected

Non-protein enzyme helpers

a.) Inorganic (Mg2+)

b.) Organic (coenzymes ie: NAD+ , FADH2)

-mimic substrate (S) & bind to enzyme active site, preventing substrate (S) from binding 

-Reversible: increased S concentration can "kick out" inhibitor from active site

-binds allosteric (other) site on enzyme, changing conformation of active site, preventing binding of S to active site

-Irreversible: Increase in S does NOT reverse inhibition

Type of allosteric activation

substrate binding to one subunit's active site stabilized the active site of other subunits

The end product of a multi-step reaction serves as an allosteric inhibitor to one of the first enzymes in the process

*When large amounts of end product accumulate