enzymes Flashcards
what is the role of enzymes
to speed up metabolic reactions in living organisms
why can enzyme be reused?
they remain unchanged
give 3 benefits of enzymes compared to chemical catalysts
they can be re-used
they work well in body conditions
they are specific for certain reaction
what is an anabolic reaction
breaking 1 substrate into 2 products
what is a catabolic reaction
2 substrates need to break to result in one product
describe how an anobolic reaction occurs
the enzyme holds 2 molecules close together at the active site and the bonds then join them together
describe how a catabolic reaction occurs
the active site holds the substrate in the correct position to put a strain on certain bonds, the bonds break gibing 2 products
what are intracellular enzymes
act inside a cell
what is the enzyme called which breaks down hydrogen peroxide
catalase
what is the equation for the break down of hydrogen peroxide
2H2O2–> 2H2O+O2
what is the turnover of the enzyme catalase
6 million per second
what is a metabolic pathway
a series of enzymes that result in the final product
what is an extracellular enzyme
enzymes that are secreted out of the cell
give an example of an extracellular enzyme
digestive enzyme
what does amylase break down
starch
what does pepsin break down
proteins
what does lipase break down
lipids
what is fungi made up of
hyphae threads
what are 2 models for enzyme action called
lock and key model
induced fit
describe the lock and key model
the substrate is a complimentary shape to the active site of the enzyme (rigid shape) and fits in perfectly, chemically compatiable
describe the induced fit model
enzyme and substrate don’t fit perfectly, as the substrate fits into the active site there is a slight change in the shape of the active site (moulds around), they had to be chemically compatiable with eachother
why do cells only need a very small concentration of each different enxyme
can be re-used again and again
what does the Q10 value mean
the rate of reaction doubles for every 10 degree temperature rise
what is the equation for the Q10 value
ROR (T+10 degree)/ ROR at T degree
how does the structure of enzymes that are in extreme environments adapt
lots of disulfide bonds so as the temperature rises it does not change shape or denature
draw the graph of change in pH
what changes if the pH changes
the balance of ions change
what bond does a change in pH affect
ionic bonds
what is the ion for acids
H+
what is the ion for alkalines
OH-
what pH do most enzymes work best at
7
what is used to fix the pH of a solution
buffer solution
describe what happens when the substrate concentration increases
the ROR increases to a certain point, any further addition of the substrate does not increase the ROR
describe how an enzyme catalyses a reaction
enzyme + substrate
creates an ESC
forms an EPC
enzyme + product
describe what happens when the enzyme concentration increases
with more enzymes present, more substrates will bind to an empty active site on an enzyme, once there are no more substrates left the ROR has not continue
explain why an increase in temperature increases the rate of enzyme activity
the enzyme and substrate will have more kinetic energy and collide more, so there is more ESC meaning more product is released
what is an enzyme inhibitor
molecules that prevent enzymes from carrying out their normal function of catalysis
what is a competitive inhibitor
a molecule that fits in the active site blocking the substrate and stops the catalytic reaction
give an example of a competitive inhibitor
statins to reduce blood cholesterol concentration
what is a non-competitive inhibitor
binds to the enzyme other than the active site (allosteric site)
does substrate concentration affect the inhibitor in competitive inhibitors
yes
the substrate added, teh greater chance it will out compete the inhibitor for the active site and the more ROR will increase
will increasing the substrate concentration make any difference to the ROR in a non-competitive inhibitor
no as the enzyme has permantly changed shape
give an example of a non-competitive inhibitor
PPI’s (block enzyme activity which releases stomach acid to stop stomach ulsers)
give 2 characteristics of a non-competitive inhibitor
irreversible
highly toxic
give an example of an inhibitor which can be a metabolic poison and explain it
cyanide
attach to the enzyme involved in cellular respiration and causes the organism to die
what is an ‘end-product inhibition’
when a product of a reaction can inhibit one of the enzymes involved in its own production
why are ‘end product inhibition’ useful (2 ways)
regulates the metabolic pathway (don’t make too much product)
avoids wasting cell resources
what are enzymes called when they are made in inactive forms
pre-cursors
what is the reason for pre-cursors
to prevent damage of our cells
what needs to happen for
pre-cursors to be activated
they need to undergo a change in shape of their active site with the help of co-enzymes and co-factors
what helps change the change shape of the pre-cursors active site
adding a co-factor or co-enzyme
what is a apoenzyme
a pre-cursor (inactive)
what is a holoenzyme
an active pre-cursor
give 2 characteristics of a co-factor
inorganic
not used up in a reaction
give an example of a co-factor
chloride ions needed to activate salivary amylase which digests starch
what are co-enzyme and co-factors
increase enzyme activity
give 2 characteristics of co-enzymes
organic
altered by the reaction
give an example of a co-enzyme
vitamins
what is a prosthetic group
they are co-factors or co-enzymes that are tightly attached to an enzyme and may be permanently attached
What do co-factors do to promote enzyme activity
Helping the enzyme and substrate join
How do co-enzymes increase enzyme activity
They act as carriers moving chemical groups between different enzymes in metabolic pathways
