enzymes Flashcards
whats a catalyst
a substance that speeds up a reaction without changing the substances produced or being changed itself
can catalysts be used again
yes
what are enzymes
biological catalysts that control the rate of reactions that take place in individual cells and in whole organisms
how are enzymes efficient
they dont change the conditions in cytoplasm when speeding up reactions
-remain unaffected and can be used again
what type of proteins are enzymes
globular proteins
how are enzymes produced
during protein synthesis as the mRNA transcribed from the DNA molecule us translated
why are enzymes so specific
as a result of their primary secondary tertiary and quaternary structure
specificity
features and functions of enzymes that means as a result of specific shapes each enzyme will only catalyse a specific reaction or group of reactions
what bonds hold proteins in enzymes together
intramolecular bonds
what effects the efficiacy of the enzymes
change in temp or PH
how do temp and PH effect efficacy of enzymes
they affect the intramolecular bonds within the protein that are responsible for the shape of the molecule
anabolic reactions
reactions that build new molecules inside cells
catabolic reactions
reactions that break down substances inside cells
metabolism
sum of anabolic and catabolic reactions in a cell
metabolic pathway
series of linked reactions in the metabolism of a cell
can enzymes slow down and stop reactions
yes
intracellular enzymes
enzymes that catalyse reactions within cells
extracellular enzymes
enzymes that catalyse reactions outside of the cell in which they were made
three types of names enzymes have
-short name of what enzyme works on or what it does with ase on end
-longer systematic name describing type of reaction being catalysed
-classification number
activation energy
energy reacting molecules need to have to break the chemical bonds that hold them together
how does raising the temp increase chemical reactions rate
by giving more molecules energy to react
why are enzymes needed to increase temp for reactions
normal cells couldnt survive under energy demand and extreme heat needed
how do enzymes cataylse reactions
by lowering the activation energy needed for the reaction to take place
what do enzymes have to do to lower the activation energy
form a complex with a substrate or substrates of the reaction
what happens once an enzyme reacts with a substrate
the products formed are released and the enzyme is free to catalyse more reactions
lock and key hypothesis
when active site has for for specific substrate
what lowers the activation energy
the formation of the enzyme substrate complex
what happens when a complex is formed lock and key
what happens once reaction complete enzymes lock and key
products no longer fit the active site and complex breaks up releasing products and freeing enzyme for more reactions
induced fit hypothesis
active site more flexible and fits around substrate
what happens once substrate enters active site induced fit
shape of site molded around substrate to form active complex
what happens once reaction complete induced fit
enzyme reverts to inactive relaxed form waiting for another substrate
how can you measure the way a factor effects the rate of reaction
the initial rate of reaction each time independent factor changed
what must be kept in excess when measuring rate of reaction for enzymes
substrates unless substrate concentration rate is being measured
whats the initial rate of reaction
when the reaction proceeds at its fastest rate
whats the active site
a small depression in the enzyme caused by the way the enzyme is folded
molecular activity
number of substrate molecules transformed by one enzyme per minute
what happens when there are to many substrates
the enzymes become saturated and not enough enzymes so rate of reaction effected
how does PH effect rate of reaction
PH effects R groups that hold together enzymes bonds
how can some enzymes work at high temps
large amount of hydrogen and disulphide bonds
enzyme inhibitors
stop enzymes from working
reversible inhibitors
dont change enzyme forever
2 types of reversible inhibitors
competitive and non competitive
shape of competitive inhibitor
same shape as substrate
what does competitive do
competes with substrate to form complex
what happens if amount of inhibitor fixed
percentage of inhibition decreased by increasing substrate concentration
what do non c do
form complex with enzyme or with enzyme substrate complex
inhibition of non c
only effected by concentration of inhibitors not substrate
how does inhibiton of non c work
change active site shape or complex of substrate and enzyme deform
irreversible inhibitors
change enzyme forever
inhibition of irreversible inhibitors
inhibitor combines with enzyme by permenant covalent bonding to one of the groups vital for catalysis to occur
how do cells control so many reactions
-membrane compartment of reactions apart
-variations in PH can change rate of enzymes
-
regulatory enzymes
have seperate site to active site where molecules can bond to have activating or inhibiting effect
end product inhibiton
enzyme at begining of reaction inhibited by product at end
describe the structure of starch
alpha glucose
glycosidic bonds
amylose has 1-4
amylopectin has 1-6 and 1-4
amylose is coiled
amylopectin branched
compact molecule
explain what a catalyst is
speeds up rate of reaction
without being changed
lowers activation energy
provides different pathway
whats hydrolysis
breaks glycosidic bonds
use of water
why bread tastes sweet after chewing for long
maltose disaccharide
glucose mono
produced to taste sweet
why is caffeine not an amino acid
no amine group
no carboxyl group
no R group
why does malonate inhibit enzyme
it has similar structure so can bind into active site and act has competitive inhibitor
why increasing temp of enzyme reaction changes rate of reaction
-higher Ek so more substrate enzyme complex formed
-high temps denature so less rate
-bond changes altering enzyme shape
-substrate no longer fits active site
why rate of reaction decreases over time
hydrogen peroxide converted into products so less substrate to form complex with enzymes
how tropolone effects rate at which grapes turn brown
tropolone similar to substrate
acts as competitive inhibitor
prevents from binding
