Module 2: Section 4 - enzymes Flashcards
(43 cards)
what are enzymes
biological catalysts and proteins
what is the difference between intracellular and extracellular enzymes
intracellular-within the cell
extracellular-outside the cell
what is an example of an intracellular enzyme and what does it do
Catalase is an enzyme that works inside the cells to catalyse the breakdown of hydrogen peroxide to harmless oxygen and water
what is hydrogen peroxide
is the toxic by product of several cellular reactions, if left to build up it can kill cells
what are extracellular enzyme examples and what do they do
-Amylase and Trypsin
-Amylase catalyses the breakdown of starch to maltose
-Trypsin catalyses the breaking down of peptide bonds
what type of proteins are enzymes
Globular
what is the specific shape of the active site determined by
enzymes tertiary structure
How do enzymes speed up the rate of the reaction
by lowering the activation energy
(its the formation of the enzyme substrate complex that lowers the activation energy)
what is activation energy
the minimum amount of energy required for a reaction to occur
why does the formation of the enzyme substrate complex cause the activation energy to be lowered
1)if 2 substrate molecules need to be joined, attaching to an enzyme holds them closer together, reducing repulsion between the molecules
2)if enzyme is catalysing a breakdown reaction, fitting inti the enzyme puts a stain on the bonds so it breaks easier
explain the lock and key theory
when a substrate binds to a complementary active site and forms an enzyme-substrate complex
explain the induced fit model
the substrate and active site a different shapes so as the substate binds the active site changes shape forming an enzyme substrate complex
what are the factors that affect enzyme activity
temperature
PH
enzyme concentration
substrate concentration
competitive and non competitive inhibitors
how does temp affect enzyme activity
more kinetic energy so molecules move faster so more chances for successful collisions(the energy of the collisions also increases so more likely to result in a reaction)
why does a reaction stop if the temperature gets too high
the rise in temp makes the enzymes vibrate more and if the temp is too high the vibration breaks some of the bonds and the active site changes shape
what is Q10 also known as
the temperature coefficient
what does the temperature coefficient or Q10 show
how much the rate of the reaction changes when the temperature is raised by 10 degrees
how does Ph affect enzymes activity
above the optimum Ph the H+ ions and below the optimum PH the OH- ions can mess up the ionic and hydrogen bonds that hold the enzymes tertiary structure in place so the active site changes shape and the enzyme denatures
How does enzyme concentration affect the rate of reaction
the more enzyme molecules the more likely the substrate is to collide with on of them and for an enzyme substrate complex.
How does the substate concentration affect the rate of the reaction
more substrates so a collision between the substrate and enzyme is more likely. This is until the saturation point(all the active sites are full) and increasing substrate concentration doesn’t make a difference
What is a competitive inhibitor?
A competitive inhibitor is a molecule that competes with the substrate for binding to the active site of the enzyme.
-It binds to the active site, preventing the substrate from attaching.
-The effect can be overcome by increasing substrate concentration, as this increases the chance of substrate molecules binding to the enzyme instead.
How does a competitive inhibitor affect enzyme activity?
Reduces the rate of reaction because fewer substrate molecules can bind to the enzyme.
The maximum rate of reaction (Vmax) remains the same as if no inhibitor is present, but it takes longer to reach this rate.
What is a non-competitive inhibitor?
A non-competitive inhibitor is a molecule that binds to a site other than the active site (called the allosteric site) on the enzyme.
This binding changes the shape of the enzyme and the active site, preventing the substrate from binding effectively, even if the substrate concentration is high.
It does not compete with the substrate for the active site.
How does a non-competitive inhibitor affect enzyme activity?
Decreases the rate of reaction because the enzyme’s active site is no longer in the correct shape for substrate binding.
The maximum rate (Vmax) is lowered, meaning the enzyme can never reach the same rate of reaction as without the inhibitor, no matter how much substrate is present.
