Quick Review of Proteins
* Proteins, or polypeptides, are
polymers made of monomers called
amino acids
*There are 20 different amino acids,
so there are many varieties of
proteins.
* They are found hair, nails, muscle,
bone and in foods like meats,
cheeses, and peanuts.
Enzymes are special proteins
that speed up chemical
reactions by lowering the
activation energy needed to
start the chemical reaction.
It takes more energy to
get the reaction to
happen without the
enzyme (blue hill) than
with the enzyme (red
hill).
Because enzymes lower
the activation energy,
reactions can happen
with less energy so they
can happen faster.
They are biological catalysts. Catalysts
are chemicals that can speed up a
chemical reaction.
For example – a match could be
compared to a catalyst because it helps
start and speed up the reaction of
combustion (burning)
But unlike matches,they are not
used up in the chemical
reaction, but are reused over
and over.
We could not survive without
enzymes, because chemical
reactions do not happen fast
enough without them for our
bodies to work right.
An enzyme can make a reaction
happen MILLIONS of times
faster than it would happen
without the enzyme.
Enzymes do many jobs in the
body, they can:
• Assist in getting energy out of the foods
you eat
• Build cellular structure
Enzymes do many jobs in the
body, they can:
• Transfer information throughout the body
• Assist chemical pathways (the chains of
chemical reactions that have to happen for
living things to function)
There are thousands of
enzymes(proteins) in your body
because each works by binding
only to a specific substrate
(chemical reactant).
Every enzyme has a name and
most end in –ASE, like the
enzyme that breaks down
hydrogen peroxide (H2O2),
which is called catalase. Other
enzymes name examples:
amylase, kinase, anhydrase,
protease.
An important part of how an
enzyme works is its shape.
Enzymes have to fit their
substrate perfectly, like a lock
and key.
Enzymes work by attracting and
sticking to the reacting molecules ,
making it easier for them to meet.
(Kind of like a dating service for
molecules)
Enzymes hold the reacting
molecules (aka substrates) the
right way so that the reactive
groups are brought together.
Enzymes have evolved over
time to do very specific jobs in
very specific environments.
Changes in pH (acidity) or
temperature will change the
shape of the enzyme and may
make it either less effective, or
completely useless.
Enzymes have to work at the
right temperature and pH for
your body, and your body has to
maintain a stable internal
environment (homeostasis) to
keep its enzymes working
properly.
Since enzymes are proteins and
proteins are polymers of amino
acids, if the amino acid
sequence is changed, then the
shape of the protein changes
too.
leu-val-arg-iso-thr
leu-lys-arg-iso-thr
The other thing that affects the rate
an enzyme works at is the
concentration of
reactants(substrates) and products
of the chemical reaction it speeds
up.
A high concentration of
reactants (substrates) makes
the enzyme more effective. A
high concentration of products
makes the enzyme less
effective.
Questions:
–Enzyme names end with?
–What is activation energy?
–What do enzymes do to
activation energy?
–What do enzymes bind with?
Questions:
–List 4 types of jobs enzymes
do?
–Name 3 things that affect
enzyme effectiveness?
–How many enzymes does
your body have?
Questions:
–How many jobs does each
enzyme do?
Summary:
In 1-2 sentences, summarize
how enzymes work, and what
you have learned about them.