enzymes Flashcards
what is an enzyme?
-biological catalyst which speeds u metabolic reactions (catabolic-breaking down and anabolic-building up)
-globular protein -tertiary structure
-remains unchanged after reaction
how is the specificity of an enzyme determined
by the shape of the active site which is determined by the R group
explain an intracellular enzyme
giveexample
-works inside a cell
-catalase- catalyses breakdown of hydrogen peroxide which is a toxic by product in cells into harmless water and oxygen
explain an extracellular enzyme
give the two examples
works outside of cells e.g digestive system
-amylase - in saliva catalyses the hydrolysis of starch into maltose
-trypsin - produced by pancreas secreted into small intestine, catalyses hydrolysis of peptide bonds between polypeptides
how does an enzyme carry out its function
-substrate binds to the enzyme’s complimentary active site forming the enzyme-substrate complex
-enzyme catalyses the break down or joining of substrate forming the enzyme-product complex
-the product diffuses and enzyme remains unchanged
what is activation energy and how do enzymes affect it
-amount of energy required for a chemical reaction to start
-enzymes lower it:
-if two substrate molecules need to be joined enzyme reduces repulsion between them by holding them together
-if substrate needs to be broken down, fitting into the active site puts a strain on the bonds in the substrate
what are the two theories/ models about enzymes
-lock and key model- active site fixed and doesn’t change shape- incorrect
-induced fit model- tertiary structure active site changes shape and moulds around the substrate tightly - correct
what factors affect enzyme activity
-temperature
-pH
-enzyme concentration
-substrate concentration
explain how temperature affects enzyme activity
draw the graph
-increases kinetic energy of enzyme’s molecules= more successful collisions= increased rate of reaction
-until temp is too high= vibrations break the bonds holding enzyme’s tertiary structure= denature
how to do find the temperature coefficient (Q10)
Q10 = R2 (Rate at higher temp)/ R1(rate at lower temp
every 10 degrees
how does pH affect enzyme activity
draw the graph
-above and below optimum pH, the H+ and OH- ions can mess with ionic bonds and hydrogen bonds in enzyme’s tertiary structure = enzyme denatures
how does concentration affect enzyme activity
draw the graph
-as enzyme concentration increase, rate of reaction increases due to more chances of collisions until substrate becomes a limiting factor
how does substrate concentration affect enzyme activity
draw the graph
-as substrate concentration increases, rate of reaction increases due to more chances of successful collisions until enzyme active sites become a limiting factor.
