2.4 enzymes Flashcards
what are enzymes
biological catalysts that speed up the rate of reactions without being used up
what is the active site of an enzyme
area on the surface which is complementary to the shape of the substrate molecules
what is a catalyst
chemical/ substance that speed up the rate of reaction without being used up/changed
what is the turnover number
the number of reactions that an enzyme molecule can catalyse per second
what is an extracellular enzyme and exapmles
works outside of cells
amylase, trypsin
what is an intracellular enzyme and examples
made and retained in the cell
catalase
what are metabolites
the reactants, intermediates and products
what is a catabolic reaction
metabolites are broken down into smaller molecules and release energy
what is an anabolic reaction
energy used to synthesise larger molecules
what is metabolic/metabolism
the chemical reactions that that place inside cells
what is a product and substrate
molecule produced from substrate molecules
molecule altered by an enzyme
what does catalase do, consist of and where is it found
protects the cell from damage from reactive oxygen by breaking down hydrogen peroxide
4 polypetide chains and a haem group (iron)
vesicles
what does amylase digest, where is it produced and acts
starch into maltose
pancreas/salivary glands
acts in the mouth
what does trypsin do, where is it produced and acts
digests proteins into smaller peptides by hydrolysing peptide bonds
pancreas
acts in the lumen of small intestines
describe the induced fit model and how it releases products
the active site and substrate still have a complementary shape
when binded the active site changes shape so it fits around the substrate more closely forming an enzyme substrate complex
products have been converted it forms an enzyme product complex which detaches due to difference in shape from the active site released
what is an enzyme substrate complex
enzyme with substrate molecule in its active site bound by non covalent bonds
what is a enzyme product complex
substrate is built up or broken down into a product in its active site bound by non covalent bonds
describe the lock and key model forming smaller products
active site is a fixed shape and complementary to substrate
temporary hydrogen bonds hold substrate and enzyme together forming enzyme substrate complex
substrate broken down into smaller products
describe the lock and key model forming larger products
two smaller substrates fit into active site, forms an enzyme substrate complex
bonds form between substrate molecules forming an enzyme product complex
larger product leaves the site
describe the induced fit hypothesis
substrate and active site are complementary
active site changes shape of the side chains (R groups) slightly to have a closer fit
how do enzymes lower the activation energy
specific active site to substrate
brings the molecules close without excessive heat
so activation lowers and rate of reaction speeds up
identify the factors impacting rate of enzyme activity
temperature
pH
enzyme concentration
substrate conc.
how does temperature speed up metabolic reactions
gains kinetic energy so molecules move faster
increases rate of successful collisions
rate of ES complexes increases so the ROR increases
up to the maximum point/ optimum temperature
how are enzymes denatured by temperature
heat makes molecules vibrate which breaks weak bonds holding the tertiary structure of enzymes active site
ROR decreases as substrates no longer fit
as more heat applied the active site irreversibly changes and is no longer complementary
reaction no longer takes place = denatured
