Core Concept: Enzymes and biological reactions Flashcards
Define metabolism
And metabolic pathway
all of the organism’s chemical processes, comprising anabolic and catabolic pathways
a sequence of enzyme-controlled reactions, in which the product of one reaction is the substrate for the next
Function of Enzymes
enzymes are a biological catalyst that alters the rate of a chemical reaction without being used up in the reaction
Enzyme effect on Ea and rate of reaction
lowers activation energy increasing the rate of reaction
Shape, structure and bonds of enzymes
globular shape
tertiary stucture 3D
peptide, hydrogen, ionic and disulphide bonds
What sites do enzymes act in
extracellular- secreted from cells by exocytosis to catalyse extracellular reactions eg saprotrophic.
intracellular in solution- enzymes in cells that catalyse the breakdown o glucose in glycolysis
intracellular membrane bound- attached to membranes
Name the two different theories of enzyme action
lock and key theory
induced fit theory
Describe lock and key theory
enzyme active site is fully complementary to the shape of the substrate when the substrate collides with suffiecient energy an enzyme-substrate-complex forms and produts are released
Describe induced fit theory
enzyme active site is not fuly complementary to the shape of the substrate, when a substrate collides with suffieicient energy the enzyme undergoes conformational changes to its shape which makes the active site form tighter around the substrate (enzyme-substrate-complex forms) this causes the bonds within the substrate to weaken causing a decrease in Ea
Factors affecting enzyme activity
5 points
Temperature
pH
Enzyme concentration
Substrate concentration
inhibitors
effect of Temperature on enzyme action
kenetic energy of the substrates increases so a higher proportion of substrates have a successfull collision and an enzyme-substrate-complex forms rate increases until the optimium temperature is reached at which point further increase in temperature causes more vibrations in the enzyme so hydrogen bonds are broken this changes the tertiary shape of the enzyme so the active site is no longer complimentary to the substrate (enzyme is denatured) enzyme-substrate-complex no longer forms so rate decreases.
effect of pH on enzyme action
enzymes have an optimium pH a small chage in pH causes a small change to the structure of the enzyme making it less effiecient (rate decreases slightly) but change is reversible
a large deviation from this pH however will cause the disruption of ionic bonds and hydrogen bonds this causes a change in the tertiary shape of the enzyme including the active site so it is no longer comlimentary to the substrate no enzyme-substrate-complexes form enzyme is denatured so rate decreases
effect of Enzyme concentration on enzyme action
rate of reaction increases as enzyme concentration increases (directly proportional) the enzyme concentration is the limiting factor. ROR increases until the substrate concenttration is the limiting factor then the graph plateaus
effect of substrate concentration on enzyme action
rate of reaction increases as substrate concentration increases (directly proportional) the substrate concentration is the limiting factor. Rate of reaction increases until the substrate concentration is the limiting factor then the graph plateaus
effect of inhibitors on enzyme action
if the inhibitors has reversible changes to the enzyme rate of reaction decreases as inhibitor concentration increases due to the decrease in the formation of enzyme-substrate-complexes but the same amount of products is reached
if the inhibitors changes are irreversible rate of reaction decreases as inhibitor concentration increases due to less enzyme-substrate-complexes forming but and less yeild is acheived as once the inhibitor binds no due to enzyme-substrate-complexes with that enzyme can be formed again
Name 2 types of inhibitors
competitive
non-competitive
