Enzymes Flashcards
What is an anabolic enzyme?
Building up new substances and structures to form new cells and whole organisms
What is a catabolic enzyme?
Breaking down substances such as the metabolic pathways in respiration or digestion
What is an active site and what is it complementary to?
Specific to the substrate complementary to the substrate
What is the name given to the enzyme and substrate combination?
Enzyme substrate complex
What is the name given to the enzyme and product combination?
Enzyme product complex
What is the activation energy of an enzyme and what does the energy prevent?
Enzymes lower activation energy and the energy prevents molecules from breaking down spontaneously
What is activation energy?
The energy required to start the reaction
What kind of protein is an enzyme?
globular
What level of structure is important ?
Tertiary
What does the lock and key hypothesis assume?
The substrate is exactly complementary to the active site
What is the induced fit theory?
The substrate isn’t an exact fit. When it binds it caused the enzyme to bend around the substrate resulting in the close fit.
What is an intracellular enzyme?
Act within the cell
Why is catalase important?
Hydrogen peroxide is a toxic product of metabolic pathways, catalase breaks it down into water and oxygen
What is the equation for the breakdown of hydrogen peroxide?
2H2O➡️ 2H2O+ O2
Why do large molecules need to be broken down?
They cannot enter cells directly
What is an extra cellular enzyme?
Enzymes can be secreted from the cell the break down large molecules so the products can be absorbed. Enzymes released from the cells in this way are extra cellular
Give an example of an organism that digests it’s food outside of its body extracellularly
Saprophytic fungi
What does amylase do?
Starch is broken down into maltose using the extracellular amylase
Where is amylase released from in the human body?
Salivary glands and pancreas
What does trypsin do? And where is it produced?
Breaks down proteins into smaller polypeptides. Produced in the pancreas secreted into the small intestine
how does substrate concentration affect the rate of reaction?
higher concentration= faster reaction as more substrate means more likely to be collisions between the enzyme and substrate
what is saturation point with the amount of substrate ?
after a certain point all of the active sites are full and this is all the enzymes can cope with so adding more substrate makes no difference
what effect does enzyme concentration have on the rate of reaction?
more enzyme molecules results in more collisions to form enzyme substrate complexes so increases the rate of reaction
what happens when the amount of substrate is limited with enzyme concentration?
there comes a point when there’s too many enzyme molecules to deal with the amount of substrate so adding more has no effect
how does pH affect enzyme activity?
enzymes work best at the optimum pH value, for most human enzymes this pH is 7, however above and below the optimum pH the H+ and OH- ions found in acids and alkalis can mess up the ionic bonds and hydrogen bonds that hold the enzymes tertiary structure in place this results in a denatured enzyme
what does the temperature coefficient (Q10) show?
this is a value that shows how much the rate of reaction changes when the temperature is raised by 10 degrees
what effect does temperature have on the rate of reaction?
rise in temp makes the enzymes molecules vibrate more, if the temp goes above a certain level this vibration breaks some of the bonds that hold the enzyme in shape , the active site then changes so the enzyme and substrate no longer fit together at this point the enzyme is denatured
what do enzyme inhbitors generally do?
prevent an enzyme from doing its job, it can be competitive or non competitive, reversible or non reversable
how does a competitive inhibitor work?
the molecule or part of it has a similar shape so the substance can block the active site. The inhibitor and molecule therefor compete with the active site
describe statins
used to reduce blood cholesterol, they’re reversible and inhibit an enzyme used in cholesterol synthesis
describe asprin
they are reversible, they inhibit the active site of a cox enzyme so prevent the synthesis of prostaglandins and thromboxane which are chemicals responsible for producing pain and fever
in non competitive inhibition where does the inhibitor bind and why does this have an effect?
the allosteric site and causes the tertiary structure to change which changes the active site
what is a cofactor and co enzyme and how tightly do they bind to the protein?
some enzymes need a non-protein component to carry put their function, they bind loosely
which enzyme requires Cl- ions and why are they required?
amylase, to form the correctly shaped active site
how can precursor enzymes be activated?
cofactors and a change in pH
