enzymes Flashcards
what is the role of an enzyme as a biological catalyst
enzymes speed up chemical reactions by acting as biology catalysts, biological catalysts are found within living organisms. they catalyse metabolic reactions both at cellular level and for an organism as a whole
what can enzymes affect
structures in an organism and functions. enzyme action can be intracelllar or extracellular
what is the role of enzymes in catalysing intracellular reactions, use catalase as an example
catalase works inside cells to catalyse the breakdown of hydrogen peroxide (toxic byproduct of cellular reactions) to harmless oxygen and water
role of enzymes in catalysing extracellular reactions use amylase and trypsin as examples
amylase and trypsin work outside cells in human digestive system .
amylase- found in saliva, secreted into mouth cells in salivary glands. it catalyses the hydrolysis of starch into maltose
trypsin- catalyses the hydrolysis of peptide bonds, turns big polypeptides into smaller ones which get broken down.into amino acids by other enzymes. trypsin is produced by cells in pancreas and secreted into small intestine
What is the mechanism of enzyme action, with reference to tertiary structure,specificity, the active site, the lock and key hypothesis, the induced-fit hypothesis, enzyme substrate complexes, enzyme-product complexes, product formation, lowering of activation energy?
Tertiary Structure: Enzymes are proteins with a specific 3D shape determined by their tertiary structure, forming an active site that binds to a specific substrate.
Specificity: The shape of the active site is complementary to the substrate, meaning enzymes are substrate-specific.
Active Site: The region of the enzyme where the substrate binds and the reaction occurs.
Lock and Key Hypothesis: The substrate fits the active site exactly, like a key in a lock.
Induced-Fit Hypothesis: The active site changes shape slightly to better accommodate the substrate, enhancing the reaction.
Enzyme-Substrate Complex: Formed when the substrate binds to the enzyme’s active site.
Enzyme-Product Complex: Formed after the substrate is converted into the product.
Product Formation: The enzyme catalyzes the reaction to form the product(s), which are released from the active site.
Lowering Activation Energy: Enzymes reduce the energy barrier, allowing reactions to occur more quickly at lower temperatures.
describe the need for coenzymes and cofactors and prosthetic groups in some enzyme controlled reactions. use examples
-inorganic cofactors- they work by helping the enzyme and substrate to bind together, they aren’t used up or changed in any way. eg chloride ions are inorganic cofactors for the enzyme amylase
organic cofactors (coenzymes)-participate in the reaction are are changed, they act as carriers moving chemical groups between different enzymes, continually recycled during the process
prosthetic groups- if a cofactor is tightly bound to the enzymes eg. Zinc ions are prosthetic groups for carbonic anhydrase (enzyme in RBC) the zinc ions are permanent part of enzymes active site
what are the effects of inhibitors on the rate of enzyme controlled reactions, including competitive, non competitive, reversible and non reversible inhibitors..
competitive inhibitors- block the active site so no substrate molecules can fit in, no reaction takes place, highconc of inhibitor= takes up nearly all the active sites and hardly any of the substrate will get to the enzyme. high conc of substrate= substrates chances of getting to an active site before inhibitor increases, so increasing the conc of the substrate will increase the rate of reaction.
non competitive inhibitors- bind to enzyme away from active site, bind to allosteric site which causes active site to change so no more substrate molecules can bind to , don’t compete with substrate molecules so increasing the concentration of substrate won’t make any difference
reversible and non reversible inhibition- reversible (not bind permanently to an enzyme) or irreversible (binds permanently) if they’re strong covalent bonds, the inhibitor can’t be removed easily and the inhibition is irreversible, if they’re weaker hydrogen bonds or weak ionic bonds the inhibitor can be removed and it becomes reversible
