Unit 1. 4 - Enzymes Flashcards
(24 cards)
what are enzymes?
biological catalysts that speed up the rate of metabolic reactions
what is the lock and key hypothesis?
that there is an exact fit between the substrate and the active site of the enzyme
what is anabolic enzymes?
enzymes that build larger products from smaller substrate molecules
what are catabolic enzymes?
enzymes that break large substrate molecules into smaller products
what is a lysozyme?
an enzyme found in tears and other secretions
function is to destroy pathogenic bacteria by breaking down their cell walls.
what is the induced fit hypothesis?
when the substrate molecule changes the shape of the active site and the active site changes to fit the substrate molecule perfectly
properties of enzymes?
specific - each will catalyse only 1 particular reaction
very efficient and will have a high turnover number - means they can convert many molecules of substrate into product per unit time
what is activation energy?
the energy needed to break existing chemical bonds inside molecules
why do enzymes lower the activation energy?
reduces the input of energy needed to allow reactions to take place ; which means they can take place at lower temps.
what are the factors that affects enzyme activity?
temperature
ph
substrate concentration
enzyme contration
what does increasing the temperature do?
increases the rate of reaction. This is because it gives molecules greater kinetic energy , increasing the chance of molecules colliding, leading to the formation of more successful enzyme - substrate complexes.
why do enzymes denature at high temps?
vibrations break the hydrogen bonds within the active site of the enzyme, causing the shape of the active site of the enzyme to change.
what happens when the enzyme concentration remains constant?
rate of reaction will increase as the substrate concentration increases. Reaction will level off once all the active sites are occupied ; number of available active sites become a limiting factor at higher substrate concentrations.
what happens if the enzyme concentration increases?
there are more active sites available and therefore rate of reactions increases
what is an enzyme inhibtor?
any substance which decreases the rate of an enzyme catalysed reaction or stops it.
can either be competitive or non competitive
what are competitive inhibtors?
structurally similar to the substrate molecule- can fit into the active site instead of the substrate molecule
prevents enzyme substrate complexes forming
what will increasing the substrate concentration do?
decrease the effect of the inhibtor as the enzyme = more likely to collide with a substrate molecule and form a successful enzymesubstrate complex
what are non competitive inhibtors?
don’t bind to the active site ; but bind to any other part of the enzyme. alters the overall shape of the molecule , including the active site. substrate molecule can no longer fit into the active site. increasing the substrate concentration will not increase the rate of reaction in this case as the substrate can no longer fit into the enzyme’s active site. successful enzyme - substrate complexes can’t form.
representing them on a graph?
only competitive inhibtion can be reduced by increasing the substrate concentration so mist be A
increasing substrate concentration won’t affect non competitive inhibtion so curve A
What can enzymes be used for?
on a wide commercial scale in food , pharmaceutical and agrochemical industires
why are enzymes immobilised?
enzyme can make direct contact with the substrate allowing the reaction to take place more quickly.
immoblised enzymes advantages?
enzyme doesn’t contaminate the product
immobilised enzymes can be recovered and reused
only small quantity of enzyme = needed
enzymes have greater stability and denature at higher temps
immobilised enzymes can catalyse reactions over a wider range of PH
more than one enzyme can be used ; can be added and removed
greater control over process
can be used in a continous process
what are biosensors?
detect biologically important molecules very rapidly even at low concentrations.
how are they used?
to measure blood glucose concentration in individuals suffering from diabetes.
