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CHEMICAL REACTIONS & ENZYMES
IaN pg. 37
MAIN IDEAS
1.
2.
3.
4.
5.
6.
7.
Chemical Reactions
Reactant
Product
Activation Energy
Catalyst
Enzyme
Substrate
Success is dependent upon effort.
Sophocles
Objective
Describe the
components &
properties of chemical
reactions explaining
how catalysts affect the
activation energy using
lecture, collaboration &
written review.
All living organisms use Energy
Law of Conservation of Energy – Energy cannot be created
or destroyed it can change form
Important Forms of Energy in Biology
Chemical, Thermal,
Electrical & Mechanical
I. Chemical Reactions
A. Process that changes 1 or more substances
into 1 or more different substances.
B. Energy is either ABSORBED or RELEASED
Reactants CO2 + H2O
(ingredients)
H2CO3
Products
(what’s produced)
Reversible
Law of Conservation of Mass – Matter cannot be created or destroyed.
Atoms are rearranged in chemical reactions.
The number of atoms in the Reactants is equal to the Products!
II. Energy in Chemical Bonds
A. Exergonic Reactions
1. Breaking bonds =
Releases energy
2. Exothermic = Releases
Heat
3. Can occur
spontaneously
B. Endergonic Reactions
1. Forming bonds =
Absorbs energy
2. Endothermic =
Absorbs Heat (Gets
Colder!)
If a reaction in one direction releases/produces energy, the
reaction in the opposite direction absorbs/uses energy.
EXERGONIC REACTION
Energy-Releasing Reaction
Activation
Energy
Reactants
=
Products
G
Energy
Released!
ENDERGONIC REACTION
Energy-Absorbing Reaction
Energy
Products
Activation
Energy
Reactants
Course of Reaction
=
G
Energy
Absorbed!
III. Activation Energy - Energy needed to start a reaction
A. Catalysts reduces activation energy
1. Enzymes = Catalysts
a. Molecule of RNA
Ribonucleic Acid) or Proteins
b. Speeds up Reactions in
c. NOT CONSUMED / NOT
CHANGED IN THE REACTION!
cells
Analogy
• Explain how enzyme
activity works like a lock
and key.
Catalyzed Reaction
• Reactants in enzyme catalyzed reaction are called
substrates
• Substrates bind to active site, precise fit
• Form enzyme-substrate complex
• Allows reaction to take place with less energy or
at a lower temperature
• Release and enzyme is free to start again
1. According to the graph, at what temperature do the two enzymes have the same amount of activity?
2. According to the graph, which enzyme has an optimum temperature of 75 degrees?
3. According to the graph, which enzyme is active over the longest temperature range?
Endergonic vs. Exergonic Reactions
Top ½ IaN pg. 36
ENDERGONIC REACTIONS
EXERGONIC REACTIONS
• Energy is …
• Energy is ...
At LEAST 5 bullet points!
At LEAST 5 bullet points!
1.
2.
Endergonic vs. Exergonic Reactions
Bottom ½ IaN pg. 36
Place the reactions below in the correct column on your table.
Label the: Reactants and Products, Endergonic or Exergonic,
Endothermic or Exothermic
3. Graph each reaction. Label each axis, reactants, products,
and Activation Energy. Title the graph
Endergonic/Endothermic or Exergonic/Exothermic.
ENDERGONIC REACTIONS
EXERGONIC REACTIONS