3B biological molecules Flashcards
characteristics of enzyme
-speed up chemical reactions by activation energy needed to start reaction
-required in small amounts as they remain unchanged after reaction and can be used again
-highly specific in action due to unique three dimensional shape
-affected by temperature as they have optimum temperature where they are most active
-affected by pH as extreme changes can denature enzyme
-some catalyse reversible reactions until equilibrium is reached
-some require coenzymes to be bounded before they can catalyse reactions
commercial uses of protease, pectinase and lactase
-protease in bio-active detergents remove proteins stains breaking down proteins into smaller fragments, making them easier to wash away.
-help to speed out extraction of fruit juices from fruits by breaking down pectin
-helps to break down lactose into glucose and galactose for lactose free milk
recite the lock and key hypothesis
-enzyme has a particular shape in which the substrate fits perfectly
-substrate is imagined like a key, whose shape is complementary to a lock, the enzyme
-active site with specific shape to which substrate binds onto active site
-once formed, products no longer fit into active site, escape to surrounding medium, leaving active site to be free to receive more substrate molecules
recite induce fit hypothesis
-induce fit model of enzyme action has flexible active site that changes shape to best fit the substrate and catalyse reaction
-binding of substrate to active site induces small conformational change in shape of enzyme for better fit, enzyme perform catalytic function more effectively
effects of temperature on enzyme as it first increase
-as temperature increase, increase KE of enzyme and substrate molecules
-results in increase number of effective collisions between enzyme and substrate molecules, more enzyme substrate complexes formed
-optimum temperature is temperature when enzyme is functioning at its maximum rate
increase in temperature beyond optimum temperature
-beyond optimum temperature, enzyme activity decrease
-at point d, enzyme lost its ability to catalyse reaction as it is denatured
what happens when enzymes are denatured
-excessive heat disrupts the intramolecular bonds which stabilise the secondary and tertiary structures of enzymes
-unfolds and loses precise shape of active site, irreversible
-if temperature is reduced, enzymes are inactivated but can regain catalytic influence when higher temperature is restored
effect of pH on enzyme activity
-O pH is maximum rate of reaction occurs, intramolecular bonds between secondary and tertiary structure are intact, conformation of active site is most ideal for substrate binding, frequency of effective collisions between enzyme and substrate molecules is highest, higher formation of enzyme substrate complex
-higher or lower pH, H plus concentration change, alters ionic charges on basic and acidic groups on side chains of amino acids,
how does substrate concentration affect enzyme function
-at low substrate concentration, reaction rate is directly proportional to substrate concentration due more frequent collisions with enzyme
-with increasing substrate concentration, increase rate drops off as more active sites are occupied
-with all active site occupied, rate reaches maximum, enzyme is saturated
how does competitive inhibitors affect the enzyme activity and how can it be prevented
-inhibitors with close structural resemblance to substrate of enzyme competes with substrate molecules for AS of enzyme, they may remain bound to the enzyme, excluding the substrate molecules from AS while it remains attached
-effect reduced by increasing substrate concentration to increase probability of of enzyme substrate collision instead of enzyme inhibitors collision, rate of reaction increases
how does non competitive inhibitors affect enzyme activity and how can it be prevented
-inhibitors with no structural resemblance to substrate combine with enzyme in region other than AS
-puts proportion of enzyme molecules out of action, results in change in conformation of enzyme including AS, less likely for enzyme to catalyse reaction
-reaction rate can never reach its maximum, lowered even when substrate concentration is increased to a high level
difference between competitive and non competitive inhibitors
-close resemblance to substrate molecule
-binds onto active site, binds onto region other than active site
-effects is not observed with increased substrate concentration
-maximum rate can be achieve if substrate concentration is sufficient high
specific function of enzyme
-build up of synthesis complex substances
-break down of food substances in cells to release energy
-break down poisonous substances in cell
