Chemical Reactions and Enzymes
Learning Targets
“I Can…”
• Explain how chemical reactions affect bonds.
• Describe how energy changes affect how
easily a chemical reaction will occur.
• Explain why enzymes are important to living
things.
Chemical Reactions
Chemical reactions can either release energy or
absorb energy.
REACTANTS: The chemicals that enter the
reaction
PRODUCTS: The chemicals produced by
the reaction
2 H2O2 2 H2O + O2
REACTANT:
Hydrogen Peroxide
PRODUCTS:
Water and Oxygen
Energy-Releasing Reactions
(Exothermic)
Energy-Absorbing Reaction
(Endothermic)
Chemical Reactions
• Chemical reactions usually require energy to get
started; this energy is called the ACTIVATION
ENERGY.
• Enzymes help reactions start by lowering the
activation energy.
• Enzymes essentially make it easier for two
reactants to find each other (in an endothermic
reaction) OR they assist in the breaking of
chemical bonds within a reactant ( in an
exothermic reaction.)
Energy-Releasing Reactions
(Exothermic)
H 2O 2
“SUBSTRATE”
H 2O + O 2
What about other enzymes?
• Meet Phosphofructokinase (PFK)!
What about other enzymes?
• PKF is an enzyme that speeds up the chemical
reaction to break down sugars from your food
into energy, ATP.
• The chemical reaction requires energy and is
one step during cellular respiration.
What about other enzymes?
• PFK is regulated according to how much sugar
is in your body. If you need to break down
more sugar for energy, then your body
activates more PFK. If you have plenty of
energy, then your body inactivates PFK and
stores the sugar for later use.
VLab: Enzymes
Learning Targets
“I Can..”
• Investigate how changes in pH, temperature,
substrate concentration, and regulators affect
an enzyme and its activity.
VLab: Enzymes
• The simulation will show the effectiveness of
the enzyme, PFK, by measuring how fast it
converts reactants to products.
• The reaction rate (velocity) will be expressed
as millimoles of product formation per minute
(mmol/min).
References
• http://www.bbc.co.uk/schools/gcsebitesize/science/tri
ple_ocr_21c/further_chemistry/energy_changes_chem
istry/revision/3/
• http://faculty.coloradomtn.edu/gcornwall/Starr%20Co
ncepts%20Animations%20and%20videos/chapter5/vid
eos_animations/catalase.html
• https://www.sascurriculumpathways.com/portal/Laun
ch?id=1
• https://prezi.com/tquzorodzbdz/phosphofructokinase/
• http://en.wikipedia.org/wiki/Phosphofructokinase_1#
mediaviewer/File:Phosphofructokinase_6PFK_wpmp.p
ng