enzymes structure + function### Flashcards
what kinds of proteins are enzymes
globular proteins
what kinds of proteins do enzymes have
mostly quaternary (some tertiary)
define catabolic reactions
break down big molecules into small molecules
define anabolic reactions
combine smaller molecules into larger molecules
what is induced fit
enzyme changes shape in order to fit substrate
define enzyme
biological enzymes used to speed up metabolic reactions
what does an enzyme inhibitor do
interfere with functioning of the active site of an enzyme
what do competitive inhibitors do
compete with substrate to occupy active site of enzyme (not permanent)
what do non-competitive inhibitors do
alter the shape of the enzymes active site so enzyme cant function (permanent)
define metabolic pathway
series of reactions in which each step is catalysed by an enzyme
how do enzyme properties relate to their tertiary structure
each different enzyme has a different tertiary structure and therefore active site. only 1 substrate can fit, so only one reaction can be catalysed
what is an extracellular enzyme
produced and secreted by cells to catalyse reactions outside of cells
how does substrate concentration affect the rate of reaction
more substrate molecules, more collisions, more actve sites used up.
increases rate of reaction up to a point
how do enzymes lower their activation energy in anabolic reactions
enzymes hold 2 substrate molecules close together, reducing any repulsion between the molecules so they bond more easily
how does enzyme concentration affect the rate of reaction
more enzyme molecules, more active sites, more likely for collisions to occur. increasing rate of reaction
what is an intracellular enzyme
catalyse reactions inside cells
what happens if substrate concentration is limited
increasing enzyme conc would have no further affect, substrate conc would be limiting factor
define enzyme
biological catalyst that speeds up chemical reactions by reducing the activation energy
why are enzymes highly specific
tertiary structure means only one complimentary substrate will fit into the active site
in relation to enzymes, what is saturation point
all active sites are full and adding more substrate s would have no further effect
why can gene mutation result in an enzyme not catalysing a reaction
changed base sequence of a gene, changing primary structure of a protein, so different R groups, and different binding between them, folding changes, 3D structure changes.
therefeore active site changes and an enzyme substrate complex cant be made
how do enzymes lower the activation energy in catabolic reactions
fitting into the active site puts a strain on the bonds in the substrate so the substrate molecules break up more easily
describe the lock and key theory
single molecule w a shape that has a complimentary fit in the active site. substrate forms temporary bonds with the amino acids in the active site forming n enzyme substrate complex
describe induced fit theory
enzymes are specific so only bond to one substance. complementary substrate enters active site and causes active site to change shape so it fits more closely around substrate
what does increasing the ph/temp do to the rate of an enzyme-controlled reaction
increases rate of reaction until optimal ph
after opt ph/temp
enzymes denature
tertiary structure of active site changes, changing shape of it
meaning enzyme-substrate complexes cant be formed
what happens if enzyme concentration is increased but substrate conc stays the same
substrate conc is limiting factor
reaction can only go to completion once all of substrate is used up
