Module 2- Enzymes Flashcards
What is the definition and function of enzymes?
-proteins that speed up reactions in living organisms
-biological catalysts
What does the lock and key theory propose?
-that enzyme and substrate fit together perfectly
-the substrate is the key fitting in the enzyme lock
What does the induced fit model suggest?
-there is more of a dynamic interaction between enzyme and substrate
-when the enzyme and substrate come together, their interaction causes a small shift in enzyme structure
What is the specificity of enzymes determined by?
-every enzyme has a specific active site that is complementary to a specific substrate
-environmental changes can change the tertiary structure of the active site and can stop the enzyme from working properly if it becomes denatured
What determines the shape of the active site?
the 3D tertiary structure of the polypeptide chain
How does temperature affect enzyme activity?
-increased temperature will increase the kinetic energy of molecules
-this increase the chance of collision between enzyme and substrate and so more collisions are likely in a set amount of time-R.O.R is faster
What does the temperature coefficient (Q10) measure?
the change in the rate of reaction when the temperature increase by 10 deg C
What is the Q10 generally around?
2
How does pH affect enzyme activity?
-changing the pH changes the number of hydroxide and hydrogen ions surrounding the enzyme
-these interact with the charges on the enzymes amino acids which affect hydrogen and ionic bonding resulting in changes to the tertiary structure
How does enzyme concentration affect enzyme activity?
-increasing it means there are more enzyme molecules availability to catalyse the substrate in a given amount of time
What are coenzymes?
coenzymes are organic molecules that bind to enzymes to increase the speed of the reaction
-are a type of cofactor
What are cofactors?
-small molecule that increases the activity of enzymes
-when a cofactor binds to an enzyme it undergoes a conformational change and the enzyme scan now catalyse a reaction
-can be either organic or inorganic
What are prosthetic groups?
-inorganic molecules that permanently bind to enzymes to form part of the structure and increase the speed of the reaction
-type of cofactor
Give an example of a cofactor
When Cl- binds to amylase it breaks down starch into sugars
What does the enzyme amylase do?
amylase in your saliva catalyses the break down of starch into sugars when you eat
What is an example of a source for coenzymes?
vitamins are an important source of coenzymes however they are not naturally produced in the body and must be supplied in the diet. If an individual doesn’t have enough vitamins in their diet the enzymes can’t catalyse the necessary reactions so may lead to health problems
What are inhibitors?
chemicals that slow down the rate or stop the reaction all together so ESCs can’t be formed or are formed at a much slower rate
What do competitive inhibitors do?
-affect the active site directly blocking the access for the formation of ESCs
What can help combat the affects of competitive inhibitors?
-increasing substrate concentration can compensate for the effects of a competitive inhibitor as there’s no permanent damage to the shape of the active site
Function of non competitive inhibitors?
-some have reversible effects but others are irreversible and denature the enzyme
-they affect another part of the enzyme molecule causing a change to the shape of the active site so it’s no longer complementary to substrate molecules
What is an inactive precursor to an enzyme?
zymogen
What is the function of a zymogen?
-needs to be cleaved to be activated and the activation is irreversible
What does an end product inhibitor do and when is it used?
-product of a reaction acts as an inhibitor to the enzyme that produces it
-this means excess products are not made and resources are not wasted
