Enzymes Flashcards
what is the turnover number?
the number of reactions an enzyme can catalyse per second
what is the role of an enzyme?
an enzyme speeds up metabolic reactions, and their actions affect structure and function within the cell and organism.
enzymes reduce the amount of energy needed for a reaction to happen and so that cells can carry out their functions
so enzymes help keep cellular functions running smoothly.
what is an intracellular enzyme + example?
this is an enzyme working inside the cell
catalase is found in nealy all living organisms that are exposed to O2. it protects cells by breaking hydrogen peroxide into H2O and O2
in eukaryotic cells catalase is found in vesciles called peroxisomes
what happens in a catabolic pathway?
metabolites are brocken down to smaller molecules and release energy
what is a metabolic pathway?
it is a series of consecutive reactions, where every step is catalysed by a specific enzyme.
describe 2 ways how metallic ion cofactors enable enzymes to work efficiently
they may bind to the active site together with the substrate to act as a co substrate to make the substrate complementery.
or they may change the charge distrubution on surface of active site which enables ESC to form more easily
what is a coenzyme?
small organic non-protein molecules that temporarily bind to the active site
what happens in an anabolic pathway ?
energy is used to synthisise larger molecules from smaller ones
what is an extracellular enzyme and give an example?
enzymes can be secreted from cells and act on their substrate from outside the cell.
amylase - produced in the salivery glands to digest starch into maltose. also made in pancreas to catalyse same reaction in lumen of small intestine
what is a cofactor?
a substance that has to be present to ensure that an enzyme catalysed reaction takes place at appropriate rate
what is a prosthetic group?
it is a cofactor that is perminantly bound by covalent bonds to an enzyme molecule
what is an enzyme-substrate complex?
it is a complex formed by temporary binding of the substrate and the enzyme
what is a co- substrate?
when they and the substate form the correct shape of the enzyme together
how are metallic ion cofactors different from prosthetic groups?
metallic ions bond temporalrily and prosthetic groups bond perminently as a pert of the structure
what bonds form between metallic ion cofactors and the enzyme?
ionic bonds
why are enzymes biological catalysts?
they speed up the rate of chemical reactions in living organisms without beings used up or a perminant change.
what bonds form between a prosthetic group and the enzyme?
covalent bonds
what bonds form between coenzymes and the enzyme or substrate molecules?
ionic or hydrogen
what is the induced fit hypothesis?
when the substrate and active site interact with each other, as substrate enters the R-groups on amino acids that make up the active site with change slightly. This is a conformational change to ensure ideal binding arrangment which maximised ability of enzyme to catalyse the reaction
how do the product molecules know when to exit the active site?
the products have slightly different shape to the subsrate so they detatch
what bonds bind the substrate to the active site?
hydrogen, ionic attractions, van der waals forces, hydrophobic interactions.
how do enzymes lower the activation energy of a reaction?
they bring the substrate close enough together to react without the need for excessive energy
why can a large amount of substrate be catalysed by a small amount of enzyme?
Because once the enzyme is done with the reaction it is free of product and is able to accept another substrate
what happens in terms of energy if a substance is heated?
this extra energy (heat) causes them to gain kinetic energy which makes them move faster, this increases the rate and force of collisions between molecules
