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Origin of Life
• Atoms make up molecules
C, H, O, N, P combine and may form CH4, H2O, NH3, H2, PO43-
• Molecules form monomers
CH4, H20, NH3 may combine and form amino acids
• Monomers combine to form polymers
Amino acids form proteins
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Definitions
• ___________: a single unit molecule that may
chemically bind to other molecules
Ex. ___________________: building blocks of protein
• ___________: a chain of repeated monomers
Ex. _____________: a large molecule formed by linked
monomers called amino acids
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Enzymes: special type of protein
• __________: a type of ________ that speeds up
chemical _________ in living organisms without
being _________ or destroyed.
• Chemical reactions are synonymous with
metabolic reactions in biology.
• Are picky and only work on one molecule
Example: catalase only works with H2O2 (hydrogen
peroxide)
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CHEMICAL REACTIONS
Transfer of Energy
Rearrangement of Atoms
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Energy
Definitions:
• Ability to do work
• Ability to move or change matter
Energy comes in ______ forms.
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Forms of energy
• Light - sun
• Heat - shivering
• Mechanical - rub hands together
• Electrical - shock metal door knob
• Chemical - combustion
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Chemical Reactions
• Energy is transferred
• Atoms are rearranged
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Energy is Transferred
First Law of Thermodynamics:
The total amount of energy in an isolated system is
constant (not increasing or decreasing).
Energy cannot be created nor destroyed.
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Rearrangement of Atoms
__________: starting materials
Product: newly formed substances
: changes into
A+BC+D
Ex. HCl + KOH  KCl + H2O
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Energy in Chemical Reactions
• Chemical bonds are formed and broken
• Hydrogen Bonds, Ionic Bonds, Covalent Bonds
• Products can either _______ or _______ energy
• Endothermic Reaction
• Exothermic Reaction
• -gonic = suffix meaning energy
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Chemical Bonds and Reactions
• Are strong bonds easier or harder to break
compared to weak bonds? And do they require
more or less energy?
• Therefore, weak bonds are _________ to break
and require ________ energy to do so.
• Do spontaneous reactions break ‘more stable’ or
‘less stable’ bonds? Why?
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RULE OF THUMB
The more strong bonds a
molecule has, the more stable it
is; consequently, more energy is
needed to break down the
molecule.
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What is happening in this reaction?
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How would you graph
the diagram to the right?
High
Energy (heat)
Low
Time
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Endergonic Reaction
• Energy is absorbed
• Unfavorable or
_________________
• Products are less
stable than reactants
Ex 1. Photosynthesis
6CO2 + 6H2O  C6H12O6 + 6O2
Ex 2. burning paper
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What is happening in this reaction?
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How would you graph
the diagram to the right?
High
Energy (heat)
Low
Time
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Exergonic Reaction
• Energy is released
• Favorable or
spontaneous
• Products more stable
Ex. Respiration
C6H12O6 + 6O2  6CO2 + 6H2O
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Enzymes and Metabolic Reactions
Endergonic Reaction
Exergonic Reaction
• Energy is _________
• Energy is __________
• Products have ______
• Products have ______
energy than reactants
energy than reactants
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Starting Chemical Reactions
• How do endergonic and exergonic
reactions begin?
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Activation Energy
• Activation energy (EA): the energy needed to
________ a reaction
• Do spontaneous reactions require EA?
• Do non-spontaneous
reactions require EA?
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Enzyme and EA (Activation Energy)
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Role of Enzyme
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Enzymes
• protein that speeds
up metabolic
reactions
• Catalysts: _______
the activation
energy needed to
start a chemical
reaction
How do enzymes
speed up chemical
reactions?
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Importance of Enzymes
• Allow organisms to maintain homeostasis
• Without enzymes, reactions would occur too
slowly for life to exist
• Enzymes lower the activation energy needed for
chemical reactions to occur = quicker reactions
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Enzyme Specificity
• Specificity- specific, particular, precise
• Enzymes only work with certain _____________
or reactants.
• ____________: substance or molecule which an
enzyme acts on
Amylase
Starch
H2O2 Catalase
glucose
2H2O + O2
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How are enzymes specific?
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Enzyme Lock and Key Model
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What effects the performance of enzymes?
• Two things. Discuss with your table partner for a few
moments.
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THE END