Transcript enzyme powerpoint

Enzyme Notes chapter 5
What are enzymes?
Enzymes are cellular proteins that
lower the activation energy of chemical
reactions in the cell. Enzymes are
catalysts.
How do enzymes work?
The top curve represents a
reaction occurring on its own.
“b” represents activation
energy, or the amount of
energy required to hook
molecules together, or to
break molecules apart. The
curve on the bottom
compares how much energy
it take with an enzyme… a lot
less!
How enzymes work, contd
Reactions that contain enzymes will tend to
proceed faster because the don’t need as much
energy. (a.k.a TIME)
Reactions can only occur with out enzymes if
the solution reaches temperatures high enough
to cause the molecules to bump into one
another. How could temperatures this high affect
a living organism?
Enzyme structure
Enzymes are examples of proteins. They form
“blobs” because when they are being created in
the cells, the amino acid chains need to clump
together to conserve space.
The clumping forms grooves called ACTIVE
SITES.
Incorrect clumping causes active sites to form
improperly.
Why is the shape of the enzyme so
important?
If the shape is not formed correctly, the active
site groove cannot fit the substrate.
For example: Amylase is an enzyme in saliva
which helps to break down polysaccharides.
Without amylase, we would not be able to get
energy from foods high in starch because we
could not break down the individual glucose
molecules apart and use them as energy.
Shape of an Enzyme
Other examples of enzymes
Liver releases bile to break down lipids
Pancreas releases pancreatic juices to help in
digestion.
DNA is photocopied using enzymes… no DNA copy, no
new cells when you fall and scrape your leg.
Enzymes remove Oxygen from hemoglobin so that it
can get into your tissues.. NO enzyme, no oxygen, no
working muscles, brain, hearts, etc.
Destroying Enzyme Function
How can you get an enzyme to stop doing its
job?
BY DESTROYING ITS SHAPE! ENZYMES
STOP WORKING WHEN CONDITIONS ARE
NOT RIGHT!
What are the RIGHT conditions?
1)Specific temperature ranges. (The enzymes in
your body work at what temperature? The
enzymes in the bacteria that live in the hot
springs work at a much higher temperature).
2) Specific pH ranges (Your stomach enzymes
work at what pH? Your mouth?)
3) Specific substrates to fit into active sites
Denaturation
If any of the 3 conditions are changed, the
enzymes can stop functioning either temporarily
or permanently.
Sometimes the enzymes break apart and
unwinds back to the primary structure:
DENATURATIO