Lab 4 - Enzymes Flashcards
what are enzymes?
enzymes are proteins. enzymes are catalysts.
what are the properties of catalysts
in general, catalysts LOWER the energy required for the chemical reaction other properties of all catalysts: 1. increase reaction rate 2. effective in small quantities 3. do not add energy to a reaction 4. are not used up in the reaction 5. are substances (ie, heat is not a catalyst) other properties of enzyme catalysts: 1. very specific to one type of reaction 2. dependent on their shape for their effectiveness (range of conditions which are favorable to reaction)
what is it called when you alter the shape of a protein?
denatured
what can denature a protein
changes in environment – heat or pH
is denaturation permanent?
sometimes. some can be reversed. for this lab, it was not reversible.
draw maltose
what is maltose?
maltose is a disaccharide.
it is made up of 2 glucose molecules.
what is amylose?
amylose is another word for starch.
starch is a polysaccharide composed of alpha glucose monomers (1-4 bond).
what is starch?
starch is a polysaccharide composed of alpha glucose monomers (1-4 bond).
aka amylose
what is amylase?
an enzymatic protein. increases reaction rate of starch (amylose) –> maltose
what test was used to see if starch was still present?
what are the + and - results?
iodine test
(IKI, iodine potassium iodine)
iodine is naturally yellow.
in the presence of starch, the iodine is trapped by the starch and turns blue-black.
as the rxn proceeds, the samples turn dark blue –> lighter blue –> reddish brown –> reddish/brownish yellow –> initial yellow color of iodine (indicates all maltose)
what is the effect on the rate of rxn of
increasing amylase concentration?
as amylase concentration increases,
the rate of reaction increases
what is the ideal temperature for this reaction?
37 degrees celsius (body temperature)
what is the effect of lowering temperatures on this reaction?
rising temperatures?
lowering temperatures decrease the rate of reaction because there are fewer opportunities for collisions between the enzyme and starch (lower kinetic energy). colder temps do not denature proteins.
raising temperatures decreases the rate of reaction as the amylase is denatured. (it no longer has shape, so can no longer perform function)
approximately parabolic shaped with a min around 37 deg celsius
what is the effect of raising pH on the reaction?
lowering pH?
lowering or raising pH from optimal denatures the amylase enzyme. thus, the reaction proceeds more slowly as pH deviates from optimal.
approximately parabolic with a min near 5.5 pH
