Download 5.1 The Flow of Energy in Living Things

5.1 The Flow of Energy in Living
Things
• Energy is the ability to do work
• Energy is considered to exist in two states
 kinetic energy
• the energy of motion
 potential energy
• stored energy that can be used for motion
• All the work carried out by living organisms
involves the transformation of potential energy to
kinetic energy
Figure 5.1 Potential and kinetic energy
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(a) Potential energy
(b) Potential energy
(c) Kinetic energy
a: © Nice One Productions/Corbis RF
Water Gradient of a Dam
5.1 The Flow of Energy in Living
Things
• There are many forms of energy but all of
them can be converted to heat
• Heat energy is the most convenient form
of energy to measure
• Thermodynamics is the study of energy
or heat changes
5.2 The Laws of Thermodynamics
• Laws of thermodynamics govern the energy changes of
the universe, including those involved with any activity of
an organism
• 1st Law of Thermodynamics
 the total amount of energy in the universe remains constant
 energy can change from one state to another but it can never be
created nor destroyed
 during the energy conversions, some of the energy is lost as
heat energy
• 2nd Law of Thermodynamics
 the amount of disorder, or entropy, in the universe is increasing
Figure 5.3 Entropy in action
Figure 5.4 Chemical reactions and catalysis
5.4 How Enzymes Work
• Enzymes are the catalysts used by cells
to perform particular reactions
 enzymes bind specifically to a molecule and
stress the bonds to make the reaction more
likely to proceed
 the active site is the site on the enzyme that
binds to a reactant
 the site on the reactant where the enzyme
binds is called the binding site
Figure 5.5 An enzyme’s shape
determines its activity
Essential Biological Process 5A:
How Enzymes Work
5.4 How Enzymes Work
• Catalyzed reactions
may occur together in
sequence
 the product of one
reaction is the
substrate for the next
reaction until a final
product is made
 the series of reactions
is called a
biochemical pathway
Figure 5.6 A biochemical pathway
5.4 How Enzymes Work
• Temperature and pH affect enzyme activity
 Enzymes function within an optimum temperature
range
 Enzymes function within an optimal pH range
Figure 5.7 Enzymes are
sensitive to their environment
Essential Biological Process 5B:
Regulating Enzyme Activity
Figure 5.8 How enzymes can be
inhibited
5.6 ATP: The Energy Currency of
the Cell
• The energy from the sun or from food
sources must be converted to a form that
cells can use
 adenosine triphosphate (ATP) is the energy
currency of the cell
5.6 ATP: The Energy Currency of
the Cell
•
The structure of ATP suits it as an
energy carrier

each ATP molecule has three parts
1. a sugar
2. an adenine nucleotide
3. a chain of three phosphate groups


the phosphates are negatively charged and it takes a lot
of chemical energy to hold them together
the phosphates are poised to come apart
Figure 5.9 The parts of an ATP
molecule
Photosynthesis and Cellular Respiration
Complementary Processes
High Energy Electrons
Release Energy to make
ATP
e–
ATP
e–
e–
e–
e–
NADPH
e–
Mill
makes
ATP
e–
Photosystem II
Photosystem I
Location of Photosynthesis
(a) Leaves
Copyright © 2011 Pearson Education, Inc.
Location of Photosynthesis
cuticle
upper
epidermis
mesophyll
cells
(a) Leaves
lower
epidermis
(b) Internal leaf structure
Copyright © 2011 Pearson Education, Inc.
Location of Photosynthesis
cuticle
upper
epidermis
mesophyll
cells
(a) Leaves
lower
epidermis
(b) Internal leaf structure
(c) Mesophyll cell containing chloroplasts
Copyright © 2011 Pearson Education, Inc.
Location of Photosynthesis
cuticle
upper
epidermis
mesophyll
cells
(a) Leaves
lower
epidermis
outer membrane
inner membrane
thylakoid
(b) Internal leaf structure
stroma
(d) Chloroplast
(c) Mesophyll cell containing chloroplasts
Copyright © 2011 Pearson Education, Inc.
A Chloroplast
outer membrane
inner
membrane
thylakoid
stroma
How do Gases Get In and Out of Leaf?
How is Light Captured by Leaf?
Figure 6.2 How a photosystem
works
Figure 6.3 Plants use two
photosystems in the lightdependent reactions
Figure 6.5 The photosynthetic electrons are
used to produce ATP and NADPH
The Light-Independent Reactions (Calvin Cycle)
Input
CO2
ATP
NADPH
CALVIN
CYCLE
Output:
G3P
Photosynthesis Overview - Simplified
Light
H2O
Chloroplast
CO2
Stroma
NADP+
ADP
P
Thylakoid
membranes
Light
reactions
Calvin
cycle
ATP
NADPH
O2
Sugar
Photosynthesis Overview - Detailed
H2O
CO2
Chloroplast
Light
NADP+
ADP
+ P
Photosystem II
Thylakoid
membranes
RuBP
CALVIN
CYCLE 3-PGA
(in stroma)
Electron
transport
chains
Photosystem I
ATP
NADPH
Stroma
G3P
O2
Sugars
LIGHT REACTIONS
CALVIN CYCLE
Cellular
respiration
Cellulose
Starch
Other organic
compounds
Figure 7.3 An overview of cellular respiration
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A5_NY
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