enzymes Flashcards
what are enzymes
soluble globular proteins
biological catalysts
anabolic reaction
building new products from substrates
catabolic reaction
breaking down substrates to products
(catastrophic)
how does extracellular action usually happen
by secretion
describe the enzyme catalase
intracellular enzyme
has a quaternary structure
has 4 haem groups
breaks down hydrogen peroxide
describe the enzyme amylase
extracellular enzyme
produced in salivary glands and pancreas
starch is partially broken down to maltose
then into glucose (by maltase)
when we increase the enzyme concentration, what is the limiting factor
substrate concentration
used up while there’s a surplus of active sites
therefore an increase in enzyme concentration has no effect on rate
how do we make a ‘linear increase’ when we add enzyme concentration
adding more substrate
when we increase the subsrate concentration, what is the limiting factor
enzyme concentration
all active sites become occupied
(substrate saturation)
therefore an increase in substrate concentration has no effect on the rate
how do we make a ‘linear increase’ when we add substrate concentration
add more enzymes
when looking at a graph for the effect of temperature on enzyme activity, what is the peak?
maximum rate
shows maximum number of successful collisions
therefore maximum number of ESC
what causes a rapid decrease after we increase the temperature past optimum
higher temperature causes breaking of bonds holding the protein’s shape
change in the tertiary structure
denaturation
(no longer complementary to the substrate active site so it can’t function)
when does the temperature coefficient not apply
when the enzymes have denatured
what is the difference in enzymes that are in organisms adapted to cold environments
enzymes have more flexible structures
making them less stable
therefore smaller temperature changes denature them
what is the difference in enzymes that are in organisms adapted to hot environments
enzymes have more bonds (esp. hydrogen bonds and sulfur bridges) in their tertiary structure
making them very stable
which means they are more resistent to change as the temperature rises
how does pH affect enzyme activity
hydrogen ions interact with polar and charged R-groups
changing the concentration of Hydrogen ions changes the degree of this interaction
how does a lower pH affect enzyme structure
more hydrogen ions present
less R-groups able to interact with each other
leads to bond breaking and shape changing
how does a higher pH affect enzyme structure
less hydrogen ions present
more R-groups able to interact with each other
leads to bond forming and shape changing
how is the maximum rate of reaction noted
Vmax
define the temperature coefficient
how is it calculated
ratio between rates at two different temperatures
rate at t+10degrees celsius / rate at t degrees celsius
if a pH is changed slightly what can enzymes do if the pH is restored to the optimum
renaturation – protein resume its normal shape
define metabolism
sum of all reactions and reaction pathways happening in a cell or organism
describe the lock and key hypothesis
only a specific substrate with fit the active site of an enzyme
when they bind, an ESC is formed
the substrates then react to form products, forming an EPC
the profucts are then released
how is the substrate held in the active site of an enzyme
R-groups in the active site of an enzyme interact with the substrate R-groups
forming temporary bonds
describe the induced fit hypothesis
the active site of an enzyme changes shape slightly as the substrate enters
define an intracellular enzyme
enzyme that works within cells
define an extracellular enzyme
enzymes that work outside the cell that made them
describe trypsin
protease
produced in pancreas and released into s.intestine
digests proteins into small peptides which break down into amino acids by other proteases
