Chapter 8: Enzymes Flashcards
what is an enzyme?
a catalytic molecule (protein or sometimes, RNA)
what is activation energy?
energy needed to get from starting state to transition state of a rxn
what is happening to a rxn when delta G = 0?
rxn is at equiilibrium
what does it mean to have a rxn with a negative delta G?
rxn is spontaneous
what does it mean to have a rxn with a POSITIVE delta G?
rxn NOT spontaneous
what 2 things to enzymes do?
- creates alternative pathways for rxns that have lower net activation energy
- makes rxns occur faster (by decreasing delta G double dagger)
do enzymes change rxn equilibrium?
no. they just change how fast the rxn achieves equilibrium
what is an RNA based enzyme called?
ribozyme
what are ribozymes made of?
RNA or RNA:protein complexes
what are 3 factors (other than enzymes) that can impact the rate of a rxn?
changes in:
temperature
pH
pressure
can a catalyzing enzyme change during a rxn?
yes but it must get changed back to its original state before the rxn ends
How much can an enzyme increase a rxn’s speed?
it can make the rxn 10 million to 10 million, million times faster
when did Dr. Shimko first mention ester linkages without explaining what those were?
chpt 8 part 1, 9 mins in
what does the term ‘ester linkage’ describe?
the bond connecting an ester’s carbonyl carbon to its OR group
in what macromolecule are ester bonds/linkages found?
lipids
are enzymes still impacted by allosteric regulators and enzyme concentration?
Yes
why did Dr Shimko show us carbonic anhydrase?
to show us how the carbonic anhydrase speeds up a bicarbonate rxn from 1 every 5 seconds to 1 million per second
video chpt 8 part 1, 11:32
why did Dr Shimko show us chymotrypsin?
to show us how the chymotrypsin speeds up a rxn to cleave amide bonds (in amino acid chains) by breaking the bonds without the need to boil them in 6M HCl for extended periods
Uncatalyzed- 1 rxn every 20 years
Catalyzed- 90 rxns per second
video chpt 8 part 1, 11:32
do enzymes still have specificity and affinity?
yes
what does it mean to say that an enzyme is permissive?
it’s not selective
is alcohol dehydrogenase still an example of selective enzyme?
yes. it will bind to ethanol, methanol, or isopropanol but prefers ethanol
are digestive enzymes examples of selective or permissive enzymes?
permissive
are transition states inherently stable or unstable?
unstable
what is a ‘nonproductive rxn’?
a rxn that achieves a transition state but reverts to substrates instead of products