energy and enzymes Flashcards
do things tend towards order or disorder?
disorder
what is NAD and what does it turn into?
an enzyme co factor that acts to carry electrons. found in all living cells.
In REDOX rxns, an H+ is transferred to NAD+ forming NADH.
NAD+ + 2e’s and 2H+’s = NADH.
The compound is a dinucleotide, because it consists of two nucleotides joined through their phosphate groups
why is NAD an enzyme ‘co factor’ ?
It’s a co factor because the enzymes needs the NAD+ to do its job; NAD+ and H+ plug into enzyme for reaction to occur
structure NAD+?
It’s a nucleotide (base, sugar , phosphate) + another nucleotide with an unfamiliar base (nicotinamide) which has a + charge
is NADH recycled?
yes. after enzyme releases it, diffuses away and is available to other molecules
endergonic
when delta G is positive- requires energy
exergonic
- Delta G is negative. Favorable/spontaneous
ATP hydrolysis= ___ kcal
-7.3
how does exergonic ATP hydrolysis drive other reactions?
- Can create coupled reactions. Use ATP hydrolysis + to push other unfavorable rxn. Its like how sodium can bring glucose in with it- pair good with bad (aka non spontaneous rxn)
example of a process that is only energetically favorable due to ATP production
glutamine formation.
glutamic acid -> glutamine = G of 3.4.
ATP-> ADP + P = -7.3.
overall G is -3.9 kcal/mol; it goes!
how do enzymes work with energy and rate of rxn? are they used up?
Enzyme lowers activation energy of rxn. Enzymes increase rate of rxn without changing equilibrium. never used up or changed.
what exactly are enzymes?
proteins, with binding sites
what occurs when the substrate goes into the binding site?
enzyme tightens grip around it , called ‘induced fit’ , by using things like H-bonds
describe the process of the enzyme working once substrate is plugged in.
- induced fit
- Destabilizes the bonds as they exist.
- by destabilizing the bonds, allows substrate to overcome the linkage between the components (ex: sucrose monomers), releasing the monomers.
- Once bond has destabilized, sugars easily fall out. Enzyme remains unchanged.
describe an enzyme pathway
product of 1st Enzyme gets taken up by 2nd E, taken up by 3rd etc. each one spits out a new substrate and eventually the last enzyme gives us a useful product.
where do you find enzymes?
both in cytoplasm and in membrane
Multisubunit enzyme complex and example of one
several enzymes activities all associating together in a big clump. Can pick up multiple substrates and immediately convert into multiple products.
ex; pyruvate
what is feedback inhibition
cells regulate the enzyme pathways. Most common way to regulate is to regulate the first enzyme by using the end product. ‘end product inhibition’ feedback inhibiton.
If you end up with 2 much final product (more than u need), it pops back up top and really slows down the process.
what are the 2 types of enzyme inhibition
competitive, noncompetitive
what is competitive inhibition
Competitive inhibition: substrate + competitor compete for binding to active site.
what is noncompetitive inhibiton
something changes the shape of enzyme, goes somewhere OTHER than active site. This non competitive is much more common type.
is there an optimum temp for enzymes to react?
yes.
And its different depending on where the enzyme lives. Human bodies operate at 37 centigrade, so our enzymes need that too. If youre living on a bacteria in a hot springs, need 75 centigrade.
how are electrons related to metabolism?
Transfer electrons from food source –> Break everything down in CO2 and water via many small steps. this is how we fully oxidize our carbon compounds
competitive inhibition: what changes, what stays same?
vmax same, Km changes
noncompetitive inhibition: what changes what stays same?
vmax changes, km same
