Download Enzymes are catalysts in living things

Enzymes
Chapter 2: Section 2.5
Objectives
• SWBAT explain the effect of a catalyst on
activation energy.
• SWBAT describe how enzymes regulate
chemical reactions and maintain homeostasis.
Starter: How can this be possible
Catalyst
• A catalyst lowers activation energy.
• Catalysts are substances that speed up chemical reactions.
– decrease activation energy
– increase reaction rate – speed up reactions.
Enzymes are catalysts in living things
• Enzymes allow chemical reactions to occur
under tightly controlled conditions.
– Like inside of a cell or intercellular space.
• Enzymes are catalysts in living things.
– Enzymes are needed for almost all processes.
– Enzymes are almost always proteins.
Detailed Definition Enzymes
• UC Davis Site:
http://chemwiki.ucdavis.edu/Biological_Chem
istry/Catalysts
• When we think about information and its
reliability, the source is important. If you
would like to read in detail about enzymes (at
a college level) check out this website.
Point of Review
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Enzymes are proteins.
Proteins are what kind of Molecule?
Answer: a carbon-based molecule.
Proteins are made up of what?
Answer: they are made up of amino acids.
Proteins are polymers of amino acids (making
amino acids monomers).
Reactions with and without enzyme
Substrate
refers to
your
reactants
Enzymes function in a small range of
conditions
• Disruptions in homeostasis can prevent
enzymes from functioning.
– Enzymes function best in a small range of
conditions (remember importance of water’s
special properties – water is a buffer).
– Changes in temperature and pH can break
hydrogen bonds (remember, organisms
have a very narrow range of temperatures, pH
and other conditions in which they can
survive).
An enzyme’s function depends on its structure.
• An enzyme’s structure allows only certain reactants to bind to
the enzyme.
substrates
(reactants)
– substrates
– active site
enzyme
Substrates bind to an
enzyme at certain places called
active sites.
An enzyme’s function depends on its
structure.
• The lock-and-key model helps illustrate how enzymes
function.
– substrates brought together
– bonds in substrates weakened
Substrates bind to an
enzyme at certain places
called active sites.
The enzyme brings
substrates together and
weakens their bonds.
The catalyzed reaction forms
a product that is released
from the enzyme.
Examples of Enzymes
• Amylase – made by salivary glands and
pancreas (facilitates the breaking down of
starch and glycogen into glucose).
• Amino acid tryptophan is the substrate for the
synthesis of serotonin.
– Serotonin is a steroid that is a neurotransmitter (a
chemical substance that transmits nerve impulses
across synapses).
– Involved in mood, appetite, sleep, memory,
learning and depression (upping levels tends to
relieve depression).