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What processes and characteristics
need to occur for something to be
considered “living”?
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Excretion : getting rid of waste
Secretion : releases usable materials
Reproduction
Growth
Use energy
Metabolize : carry out chemical reactions
Has Genetic material
Made up of CELLS!
How do our cells carry out all of
the necessary processes of life?
ENZYMES! (2.5)
Proteins
• 4 levels of structure
• The sequence of amino acids
(specifically the R-groups)
determines the overall shape
of a protein
• The function of any proteins is
dependent upon its overall
shape
• When a protein is denatured,
the intermolecular bonds are
broken, compromising the
shape of the protein, and
thereby losing its function.
Characteristics of Enzymes
• Enzymes are a specific type of protein (polypeptide)
• Quaternary level structure
• Speed up all types of chemical reactions by reducing
the activation energy required
• Do not get destroyed during reactions, but get re-used
over and over again.
• Are highly specific in their behavior which is
determined by the shape of the enzyme
• Are affected by pH and temperature
• Approximately 1,300 enzymes in the human cell.
• DNA = instructions for life ; Enzymes = workers that
carry out those instructions
• Rubisco is the most abundant enzyme in the world.
What is ACTIVATION ENERGY?
• Chemical reactions are due to
molecules physically colliding
with one another
• Molecules must have enough
energy to break and re-form
bonds (chemical reaction)
• ACTIVATION ENERGY: the
amount of energy required
for a chemical reaction to
occur
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Enzymes (Catalyst): speed up a reaction by stressing
the bonds in the reactants, providing another
chemical pathway that has a lower activation energy
(Ea)
• Enzymes only work to speed up reactions that are already occurring,
they cannot produce reactions that would not normally occur.
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Metabolic reactions would
not be possible without
enzymes
• Body temperature:
37⁰C (98⁰F)
• Polymers could not be
digested without
enzymes
• Enzymes remain
unchanged after a
reaction has occurred
• Enzymes are reused
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Example: Catalytic Converters as
Catalysts
• Catalytic converters
speed up the reaction
that converts harmful
exhaust gases into
harmless products
Nitrogen oxide and carbon monoxide are converted to carbon dioxide
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and nitrogen gas
How are enzymes used in our bodies?
• Some enzymes have 1
specific function, while
others are involved in
various types of
reactions.
• Example Functions:
– Copy DNA
– Digest food
– Obtain & metabolize
energy from food
– Synthesis of proteins
– Blood clotting
– Getting rid of wastes
(the shape of the active site determines the function of the
enzyme)
How do enzymes work? – OLD MODEL
The Induced Fit Model of How
Enzymes Work
• How Enzymes Work:
http://highered.mheducation.com/sites/0072495855/s
tudent_view0/chapter2/animation__how_enzymes_w
ork.html
Why do enzymes stop working?
What factors
affect the activity
of an enzyme?
• Temperature
• pH
• Concentration
(amount) of
substrate