FB 4 enzymes onwards Flashcards
what are anabolic reactions
building up
what are catabolic reactions
breaking down
what is the metabolism
all the different reactions and reaction pathways
what is the Vmax
enzymes can only increase rates of reaction to a certain point
(maximum initial velocity)
what are extracellular reactions and give example
act outside of cells and are secreted
as all reactions require substrates which need to be constantly supplied to cells but some (like polymers like proteins and polysaccharides) are too large to enter cells so must be broken down first.
single celled and multicellular use extracellular enzymes to make use of nutrients
fungi produce extracellular enzymes that work outside the body
amylase and trypsin are both involved in digestion in humans
describe the mechanism of an enzyme reaction
for reaction to happen, molecules need to collide with right orientation when high temperatures and pressures are applied the speed of molecules increases along with number of successful collisions and RoReaction
enzymes lower the activation energy as they help the molecules collide successfully
(specific tertiary structure)
what is enzyme specificity
many different enzymes are produced by organisms as each enzyme catalyses one biochemical reaction
what is the lock and key hypothesis
idea that the tertiary structure of an enzymes has an active site which is complementary to the shape of a specific substrate molecule.
>when substrate bound to active site an enzyme substrate complex is formed
>substrate/s reacts and product/s are formed
>enzyme is unchanged
>substrate held in a way by enzyme that R groups and atom groups are close enough to interact
what is the lock and key hypothesis
idea that the tertiary structure of an enzymes has an active site which is complementary to the shape of a specific substrate molecule.
>when substrate bound to active site an enzyme substrate complex is formed
>substrate/s reacts and product/s are formed
>enzyme is unchanged
>substrate held in a way by enzyme that R groups and atom groups are close enough to interact forming temporary bonds and puttings strain on the bonds in the substrate
what is the induced fit hypothesis
> active site of enzymes actually changes shape slightly as the substrate enters
more accepted idea/model
initial reaction between enzyme and substrate is weak but these weak interactions rapidly induce chnages to the tertiary structure which strengthen binding and putting strain on the substrate molecule
> this weakens bonds and lowers activation energy
what is the effect of pH on enzyme reaction
> hydrogen bonds and ionic bonds between R groups hold the protein in precise 3D shape
(these bonds resulted from interactions between polar R groups in the amino acids forming the primary structure)
> active site only right shape at certain H+ion concentration. if pH returns to optimum the enzyme returns to normal by renaturation
denaturation= substrates can no longer bind to active site
the more H+ ions the less the R groups are able to interact. bonds break and shape of enzyme changes.
very narrow range of pH
eg)pepsin works at pH 2
amylase pH 7 trypsin,lipase,maltase and amylase pH 8
what is the effect of temperature on enzyme reaction
> increases the KINETIC ENERGY of the particles
particles move faster and collide more frequently
enzymes work at an optimum temperature
what is the effect of enzyme concentration on enzyme reaction
rate of reaction increases to its Vmax
at this point all active sites are occupied and no more enzyme substrate complexes can form
what is the effect of substrate concentration on enzyme reaction
> more collisions with active site and more enzyme substrate complexes form and reaction increases
how is a serial dilution carried out
just read
The sample/culture is taken in a test tube and six test tubes, each with 9 ml of sterile diluents, which can either be distilled water or 0.9% saline, are taken.
A sterile pipette is taken.
1 ml of properly mixed sample/culture is drawn into the pipette.
The sample is then added to the first tube to make the total volume of 10 ml. This provides an initial dilution of 10-1.
The dilution is thoroughly mixed by emptying and filling the pipette several times.
The pipette tip is discarded, and a new pipette tip is attached to the pipette.
Now, 1 ml of mixture is taken from the 10-1 dilution and is emptied into the second tube. The second tube now has a total dilution factor of 10-2.
The same process is then repeated for the remaining tube, taking 1 ml from the previous tube and adding it to the next 9 ml diluents.
As six tubes are used, the final dilution for the bacteria/cells will be 10-6 (1 in 1,000,000).
what is the temperature coefficient
Q 10- how much the rate of reaction increases with a 10 degree rise in temperature
calculated by taking to rate of reaction at two temperatures
why do some enzymes need coenzymes, cofactors and prosthetic groups
some need non-protein helper molecules which can either transfer atoms/groups between reactions or may form part of the active site of the enzyme.
if a cofactor is organic/contains carbon its a coenzyme
what is Cl- a cofactor for
amylase
breaks down starch and contains a Cl- ions needed for active sites specific shape
what is the prosthetic group for carbonic anhydrase
Zn2+
