Download 3.6 Enzymes - hrsbstaff.ednet.ns.ca

IB Biology Core
3.6 Enzymes
What is an Enzyme?
Enzymes are catalysts that are produced by living
organisms.
A catalyst speeds up chemical reactions without being
changed by the reaction itself.
Enzymes are globular
proteins which act as
catalysts in chemical
reactions in living
things.
Chemical processes would occur at a rate that is too slow
Enzymes are composed of long chains of amino acids that
for living organisms if enzymes were not involved.
Cells can control their metabolism by controlling the
enzymes they produce.
During these chemical
reactions, one or more
substrates are catalysed
by an enzyme into a
product.
have folded into a very specific three-dimensional shape
which contains an active site.
An active site is a region on the surface of an enzyme to
which substrates will bind and which catalyses a chemical
reaction involving the substrate.
Animations!
What is an Enzyme?
http://www.northland.cc.
mn.us/biology/biology111
1/animations/enzyme.swf
How Enzymes work:
http://highered.mcgrawhill.com/sites/007249585
5/student_view0/chapter2
/animation__how_enzyme
s_work.html
Enzyme-Substrate Specificity
The active site of each enzyme has a very specific
This is known as enzyme-substrate specificity. The enzyme
and substrate fit together like a key fits a specific lock. The
enzyme is the lock and the substrate is the key.
and intricate shape and it also has distinct chemical
properties that match those of its substrate.
Not only does the
substrate molecule
fit the shape of the
active site but it is
also chemically
attracted to it.
Effects on Enzyme Activity
Enzymes can be affected by three different factors in
their environment.
A change in these factors can affect the rate at which the
enzyme will work or they can render it ineffective.
Enzymes must have the right conditions they need in
order to work effectively.
Enzyme activity is affected by temperature, pH, and the
concentration of the substrate.
http://www.kscience.co.uk/animations/model.swf
Temperature
Enzyme activity will increase as temperature
increases (often doubles with every 10˚C rise).
At a higher temperature more collisions occur between
the substrate and the enzymes due to faster movement of
molecules.
However, at high temperatures enzymes are denatured
and stop working.
High heat causes vibrations inside the enzymes which
break bonds needed to maintain the structure of the
enzyme.
PH
As pH levels increase or decrease from the optimum
level for each specific enzyme, the activity level is
reduced.
Both acids and alkalis can denature enzymes. A pH of 7
is optimum for most enzymes.
Substrate Concentration
Enzyme activity is directly proportional to substrate
concentration at low concentration levels.
As the concentration of the substrate rises, the enzyme
activity increases because random collisions of substrate
molecules and enzymes increases as the concentration of
the substrate increases.
At high substrate concentrations, all the active sites of
the enzymes will be occupied so raising the
concentration level will no longer have an effect.
Denaturation
Denaturation is changing the structure of an enzyme
(protein) that results in the loss (usually permanent)
of its biological properties.
This means it can no longer carry out its function.
Denaturation occurs
as a result of a
change in temperature
or pH.
Denaturation in Action!
Lactose free milk
http://highered.mcgraw-
Enzymes are a very
hill.com/sites/0072943696/student_view0/chapter2/animation__protein_de
naturation.html
http://www.youtube.com/watch?v=o2ju5ys3Cxc
important part of
biotechnology,
which is the use of
organisms or parts
of organisms to
produce things or
carry out useful
processes.
Lactose is a dissacharide found in milk.
Biotechnology companies culture a particular species of
The enzyme lactase is used to break it down into glucose
yeast known as Kluyveromyces lactis which grows naturally in
milk.
These yeast produce lactase which the companies extract
and purify to sell to food manufacturing companies.
and galactose (two monosaccharides).
Under normal circumstances the human body produces
enough lactase to break down any lactose consumed in the
diet.
Lactose intolerance around the world
Lactase can be added to milk to break down
lactose into glucose and galactose.
This is very helpful to people who are
lactose intolerant.
People who are lactose intolerant do not
produce enough lactase to break down the
lactose found in milk and milk products.
By adding lactase to milk, the lactose is
broken down before it is consumed
therefore making the milk product lactosereduced and it can be consumed by an
individual with lactose intolerance.
Making Lactose-Free Milk
Most people produce less lactase as they get older.
In some areas, a mutation has allowed lactase production to
continue, people with lactose intolerance do not have this
mutation.
Fun in the Lab!
First the Lactase is immobilised in alginate
Factors that affect enzyme activity
Next the beads are placed in a container
Decomposition of peroxide (H202) by Peroxidase in
beads.
over which milk can be passed.
The milk is collected and re-circulated
(pump) to convert any remaining lactose
to glucose and galactose.
The circulation is maintained until all
lactose has been converted.
This model of an industrial process allow
the lactase to be recovered and re-used
(cheaper).
Efficient conversion of lactose to glucose
and galactose.
High % lactose conversion is achieved.
All these factors reduce cost particularly
on the downstream processing and
purification.
potato and liver!