1.4.2: Enzymes Flashcards
What is a biological catalyst
Catalyst produced by living tissue, speeds up rate of reaction and is not altered by reaction
what is the term given to enzymes that ‘break down’
catabolic enzymes
what is the term given to enzymes that ‘build up’
anabolic enzymes
what are catabolic enzymes
enzymes that ‘break down’
what are anabolic enzymes
enzymes that ‘build up’
describe the structure of an enzymes and how it is specific
enzymes are complementary in shape to their substrates, the enzyme’s active site is specific to the substrate
what are the locations of enzyme action
intracellular - found in the cell (lysosomes, organelles, cytoplasm)
extracellular - found in digestion system (alimentary canal)
How do enzymes act as a catalyst
they lower the activation energy of a reaction
what is the name given to a reaction that releases energy
exergonic reaction
what is the name given to a reaction that requires energy
endergonic reaction
what is an endergonic reaction
a reaction that requires energy
what is an exergonic reaction
a reaction that releases energy
describe the lock and key mechanism
active site of enzyme is complementary in shape to substrate, forming an enzyme-substrate complex. Once reaction is complete, products are made and enzymes remains unchanged
Describe and explain the induced fit theory for an enzyme substrate complex
1 - enzyme’s active site is not initially completely complementary to substrate
2 - forces cause the enzyme to slightly altar (distort its shape) for substrate to fit similar to hand and glove
3 - enzyme substrate complex forms
what is a limiting factor in an enzyme controlled reaction
the number of available enzyme active sites
how can you calculate the rate of reaction when the dependent variable is time taken and what are the units
1 / time taken for reaction to occur (seconds)
x 1000
units = s^-1 x 10^-3
how can you calculate the rate of reaction when the dependent variable is mass or volume and what are the units
volume or mass /time (seconds)
units = cm^3s^-1
list 4 factors that affect enzyme action
temperature
pH
substrate concentration
enzyme concentration
describe the graph of the rate of reaction against temperature of an enzyme controlled reaction
initially as temp increases, rate of reaction increases, maximum rate of reaction at optimum temperature for enzyme, as temp increases beyond optimum, rate of reatcion decreases
why does the rate of reaction initially increase as temperature increases of an enzyme controlled reaction
because there is an increase in kinetic energy of enzymes and substrates and so more successful collisions -> more enzyme substrate complexes form -> more product formed per unit of time
why does the rate of reaction decreases as temperature increases beyond the enzyme’s optimum temperature of an enzyme controlled reaction
because further increase in kinetic energy causes enzyme to vibrate which breaks hydrogen bonds between r groups in tertiary structure -> change in tertiary structure -> change in shape of active site and so enzyme is denatured -> active site is no longer complementary in shape to substrate -> fewer ESC form -> less product formed per unit of time
describe a pH graph of rate of reaction in an enzyme controlled reaction
when pH is very low, enzymes are denatured (tertiary ionic bonds broken) so rate of reaction is very slow
as pH increases and reaches optimum pH of enzyme, rate of reaction is highest, as pH increases further beyond optimum, rate of reaction decreases, further increase of pH leads to enzymes denaturing (tertiary ionic bonds broken)
how do you maintain the pH of a reaction
use a pH buffer
How would you set up an enzyme control experiment
boil the enzyme then cool it
describe and explain the graph of substrate concentration against rate of reaction of an enzyme controlled reaction
initially as substrate concentration increases, rate of reaction increases because here substrate concentration is the limiting factor
after a certain substrate concentration, further increase in substrate conc results in the rate of reaction to become constant because here enzyme concentration is the limiting factor
describe and explain the graph of enzyme concentration against rate of reaction of an enzyme controlled reaction
initially as enzyme concentration increases, rate of reaction increases because here enzyme concentration is the limiting factor
after a certain enzyme concentration, further increase in enzyme conc results in the rate of reaction to become constant because here substrate concentration is the limiting factor
what is an enzyme inhibitor
a molecule that can interfere/slow down enzyme activity
how does a competitive enzyme inhibitor function and how does it affect enzyme action
inhibitor has a similar shape to the substrate and so is complementary in shape to the active site, inhibitor can bind to active site blocking substrate from doing so -> fewer enzyme substrate complexes are formed and so less product formed per unit of time
can you achieve maximum rate of reaction if there is a competitive enzyme inhibitor and if so then how
yes it can be, by increasing substrate concentration and can out compete the inhibitor
how does a non-competitive enzyme inhibitor function and how does it affect enzyme action
inhibitor has a different shape to substrate, binds to enzyme at a point other than the active site (known as the allosteric site). This changes the tertiary structure of enzyme -> changes active site -> enzyme denatures -> substrate no longer complementary in shape to active site -> fewer ESC formed and so less product formed per unit time
can you achieve maximum rate of reaction if there is a non-competitive enzyme inhibitor and if so then how
no as the enzyme has denatured
describe the process of end product enzyme inhibition and what a metabolic pathway is and when does this happen
the final product of a metabolic pathway (series of stages for a reaction) can inhibit one of the earlier enzyme in the pathway and so stop production of the product - this happens when there is excess product
