Module 2: Section 4 - enzymes Flashcards
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.
what is a co factor
cofactor is a non-protein substance that helps an enzyme perform its catalytic activity.
what are the types of cofactors
organic or inorganic
how do inorganic cofactors work
helping the enzyme substrate to bind together
do inorganic enzymes get used up and explain
No, as they don’t directly participate in the reaction they are not used up or changed in any way
what are organic and inorganic cofactors derived from
organic cofactors are derived for vitamins and inorganic metal ions
what are coenzymes
are organic molecules that bind to enzymes to increase the rate of the reaction
(coenzymes are a type of cofactors)
do organic enzymes get used up and explain
yes, as they participate in the reaction by often acting as carriers, moving chemical groups between different enzymes
what is a prosthetic group
are inorganic molecules that permeant bind to the enzyme to form part of the structure and increase the rate of the reaction
(type of cofactor)
what determines weather an inhibitor is reversible or non reversible
strengths of the bonds between the enzyme and inhibitor
if they are strong covalent bonds the inhibitor cant be removed easily so is non reversible and if its weaker hydrogen or ionic its reversible
give an example of a non reversible inhibitor and what does it do
Cyanide is a non reversible inhibitor of cytochrome and c oxidase , an enzyme that catalyses respiration reactions
Malonate does what
inhibits succinate dehydrogenase which also catalyses respiration reactions
What is end-product inhibition?
End-product inhibition is a type of feedback inhibition where the final product of a metabolic pathway inhibits an earlier enzyme in the pathway, preventing overproduction of the product.
How does end-product inhibition regulate metabolic pathways?
When the end product accumulates in high concentrations, it binds to an enzyme involved earlier in the pathway, reducing or stopping its activity. This prevents the pathway from producing more of the product than the cell needs.
Why is end-product inhibition important?
It helps to regulate the amount of product made in a pathway, preventing the cell from wasting energy and resources by overproducing substances it doesn’t need.
How does end-product inhibition work at the molecular level?
The final product of the metabolic pathway binds to an allosteric site on an enzyme involved in the pathway. This binding causes a change in the enzyme’s shape, reducing its ability to bind to the substrate and slowing or stopping the reaction.
What type of enzyme is involved in end-product inhibition?
Allosteric enzymes, which have an active site and one or more allosteric sites. The end product binds to the allosteric site, affecting the enzyme’s function.
Is end-product inhibition reversible?
Yes, when the concentration of the final product decreases, the inhibition can be reversed, allowing the enzyme to function again and the pathway to continue.
