Download Cellular respiration

Chapter 5
Photosynthesis and Cellular
Respiration
Table of Contents
Section 1 Energy and Living Things
Section 2 Photosynthesis
Section 3 Cellular Respiration
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Chapter 5
Section 1 Energy and Living Things
Objectives
• Analyze the flow of energy through living systems.
• Compare the metabolism of autotrophs with that of
heterotrophs.
• Describe the role of ATP in metabolism.
• Describe how energy is released from ATP.
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Chapter 5
Section 1 Energy and Living Things
Energy in Living Systems
• Directly or indirectly, almost all of the energy in living systems
needed for metabolism comes from the sun.
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Chapter 5
Section 1 Energy and Living Things
Energy in Living Systems, continued
Building Molecules That Store Energy
• Metabolism involves either using energy to build
molecules or breaking down molecules in which energy is
stored.
• Photosynthesis is the process by which light energy is
converted to chemical energy.
• Organisms that use energy from sunlight or from chemical
bonds in inorganic substances to make organic
compounds are called autotrophs.
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Chapter 5
Section 1 Energy and Living Things
Energy in Living Systems, continued
Breaking Down Food for Energy
• The chemical energy in organic compounds can be
transferred to other organic compounds or to organisms
that consume food.
• Organisms that must get energy from food instead of
directly from sunlight or inorganic substances are called
Heterotrophs.
• Cellular respiration is a metabolic process similar to
burning fuel.
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Chapter 5
Section 1 Energy and Living Things
Comparing Autotrophs and Heterotrophs
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Chapter 5
Section 1 Energy and Living Things
Energy in Living Systems, continued
Transfer of Energy to ATP
• When cells break down food molecules, some of the
energy in the molecules is released as heat. Much of
the remaining energy is stored temporarily in
molecules of ATP.
• Like money, ATP is a portable form of energy
“currency” inside cells. ATP delivers energy wherever
energy is needed in a cell.
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Chapter 5
Section 1 Energy and Living Things
Breakdown of Starch
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Chapter 5
Section 1 Energy and Living Things
ATP
• ATP (adenosine triphosphate) is a nucleotide with
two extra energy-storing phosphate groups.
• Energy is released when the bonds that hold the
phosphate groups together are broken.
• The removal of a phosphate group from ATP
produces adenosine diphosphate, or ADP:
H2O + ATP  ADP + P + energy
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Chapter 5
Section 1 Energy and Living Things
ATP Releases Energy
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Chapter 5
Section 1 Energy and Living Things
Comparing ADP with ATP
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Chapter 5
Section 2 Photosynthesis
Objectives
• Summarize how energy is captured from sunlight in
the first stage of photosynthesis.
• Analyze the function of electron transport chains in
the second stage of photosynthesis.
• Relate the Calvin cycle to carbon dioxide fixation in
the third stage of photosynthesis.
• Identify three environmental factors that affect the
rate of photosynthesis.
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Chapter 5
Section 2 Photosynthesis
Using the Energy in Sunlight
The Stages of Photosynthesis
• Stage 1 Energy is captured from sunlight.
• Stage 2 Light energy is converted to chemical
energy, which is temporarily stored in ATP and the
energy carrier molecule NADPH.
• Stage 3 The chemical energy stored in ATP and
NADPH powers the formation of organic compounds,
using carbon dioxide, CO2.
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Chapter 5
Section 2 Photosynthesis
Using the Energy in Sunlight
The Stages of Photosynthesis
• Photosynthesis can be summarized by the following
equation:
Sunlight
6CO2 + 6H2O  C6H12O6 + 6O2
Carbon dioxide
water
sugars
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oxygen gas
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Chapter 5
Section 2 Photosynthesis
Photosynthesis
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Chapter 5
Section 2 Photosynthesis
Photosynthesis
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Chapter 5
Section 2 Photosynthesis
Stage One: Absorption of Light Energy
• Sunlight contains a
mixture of all the
wavelengths (colors)
of visible light. When
sunlight passes
through a prism, the
prism separates the
light into different
colors.
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Chapter 5
Section 2 Photosynthesis
Stage One: Absorption of Light Energy,
continued
Pigments
• How does a human eye or a leaf absorb light? These
structures contain light-absorbing substances called
pigments.
• Chlorophyll the primary pigment involved in
photosynthesis, absorbs mostly blue and red light and
reflects green and yellow light.
• Plants contain two types of chlorophyll, chlorophyll a and
chlorophyll b.
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Chapter 5
Section 2 Photosynthesis
Chlorophyll a and b
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Chapter 5
Section 2 Photosynthesis
Stage One: Absorption of Light Energy,
continued
Pigments
• The pigments that produce yellow and orange fall leaf
colors, as well as the colors of many fruits,
vegetables, and flowers, are called carotenoids.
• Carotenoids absorb wavelengths of light different
from those absorbed by chlorophyll, so having both
pigments enables plants to absorb more light energy
during photosynthesis.
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Chapter 5
Section 2 Photosynthesis
Carotenoid
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Chapter 5
Section 2 Photosynthesis
Spectrum of Light and Plant Pigments
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Chapter 5
Section 2 Photosynthesis
Absorption Spectra of Photosynthetic
Pigments
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Chapter 5
Section 2 Photosynthesis
Stage One: Absorption of Light Energy,
continued
Production of Oxygen
• Clusters of pigments are embedded in the membranes of
disk-shaped structures called thylakoids.
• When light strikes a thylakoid in a chloroplast, energy is
transferred to electrons in chlorophyll.
• This energy transfer causes the electrons to jump to a
higher energy level. This is how plants first capture energy
from sunlight.
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Chapter 5
Section 2 Photosynthesis
Stage One: Absorption of Light Energy,
continued
Production of Oxygen
• The excited electrons that leave chlorophyll
molecules must be replaced by other electrons.
• Plants get these replacement electrons from water
molecules, which are split by thylakoid.
• The oxygen atoms, O, from the disassembled water
molecules combine to form oxygen gas, O2.
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Chapter 5
Section 2 Photosynthesis
Chloroplast
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Chapter 5
Section 2 Photosynthesis
Parts of a Chloroplast
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Chapter 5
Section 2 Photosynthesis
Stage Two: Conversion of Light Energy
• Excited electrons that leave chlorophyll molecules are
used to produce new molecules that temporarily store
chemical energy.
• First an excited electron jumps to a nearby molecule in the
thylakoid membrane. Then the electron is passed through
a series of molecules along the thylakoid membrane.
• The series of molecules through which excited electrons
are passed along a thylakoid membrane are called
electron transport chains.
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Chapter 5
Section 2 Photosynthesis
Stage Two: Conversion of Light Energy,
continued
Electron Transport Chains
• While one electron transport chain provides energy used to
make ATP, a second electron transport chain provides energy
used to make NADPH.
• NADPH is an electron carrier that provides the high-energy
electrons needed to make carbon-hydrogen bonds in the third
stage of photosynthesis.
• In this second chain, excited electrons combine with hydrogen
ions as well as an electron acceptor called NADP+, forming
NADPH.
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Chapter 5
Section 2 Photosynthesis
Electron Transport Chains of Photosynthesis
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Chapter 5
Section 2 Photosynthesis
Electron Transport Train
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Chapter 5
Section 2 Photosynthesis
Converting Light Energy to Chemical Energy
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Chapter 5
Section 2 Photosynthesis
Stage Three: Storage of Energy
• In the third (final) stage of photosynthesis, carbon
atoms from carbon dioxide in the atmosphere are
used to make organic compounds in which chemical
energy is stored.
• The transfer of carbon dioxide to organic compounds
is called carbon dioxide fixation.
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Chapter 5
Section 2 Photosynthesis
Stage Three: Storage of Energy, continued
Calvin Cycle
• The Calvin cycle is a series of enzyme-assisted chemical
reactions that produces a three-carbon sugar:
Step 1 Each molecule of carbon dioxide is added to a fivecarbon compound by an enzyme.
Step 2 The resulting compound splits into two three-carbon
compounds. Phosphate groups and electrons are added to the
compounds.
Step 3 One of the resulting three-carbon sugars is used to make
organic energy-storing compounds.
Step 4 The other three-carbon sugars are used to
regenerate the initial five-carbon compound, thereby
completing the cycle.
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Chapter 5
Section 2 Photosynthesis
Calvin Cycle
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Chapter 5
Section 2 Photosynthesis
Calvin Cycle
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Chapter 5
Section 2 Photosynthesis
Stage Three: Storage of Energy, continued
Factors that Affect Photosynthesis
• Photosynthesis is directly affected by various
environmental factors.
• In general, the rate of photosynthesis increases as
light intensity increases until all the pigments are
being used.
• Photosynthesis is most efficient within a certain range
of temperatures.
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Chapter 5
Section 2 Photosynthesis
Environmental Influences on Photosynthesis
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Chapter 5
Section 3 Cellular Respiration
Objectives
• Summarize how glucose is broken down in the first
stage of cellular respiration.
• Describe how ATP is made in the second stage of
cellular respiration.
• Identify the role of fermentation in the second stage
of cellular respiration.
• Evaluate the importance of oxygen in aerobic
respiration.
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Chapter 5
Section 3 Cellular Respiration
Cellular Energy
• Oxygen in the air you breathe makes the production
of ATP more efficient, although some ATP is made
without oxygen.
• Metabolic processes that require oxygen are called
aerobic.
• Metabolic processes that do not require oxygen are
called anaerobic, which means “without air.
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Chapter 5
Section 3 Cellular Respiration
Cellular Energy, continued
The Stages of Cellular Respiration
• Cellular respiration is the process cells use to harvest
the energy in organic compounds, particularly
glucose. The breakdown of glucose during cellular
respiration can be summarized by the following
equation:
C6H12O6 + 6O2
6CO2 + 6H2O + energy
glucose oxygen gas carbon dioxide water
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Chapter 5
Section 3 Cellular Respiration
Cellular Energy, continued
The Stages of Cellular Respiration
• Cellular respiration occurs in two stages:
Stage 1 Glucose is converted to pyruvate, producing
a small amount of ATP and NADH.
Stage 2 When oxygen is present, pyruvate and
NADH are used to make a large amount of ATP.
When oxygen is not present, pyruvate is converted to
either lactate or ethanol and carbon dioxide.
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Chapter 5
Section 3 Cellular Respiration
Cellular Respiration
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Chapter 5
Section 3 Cellular Respiration
Cellular Respiration
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Chapter 5
Section 3 Cellular Respiration
Stage One: Breakdown of Glucose
Glycolysis
• In the first stage of cellular respiration, glucose is
broken down in the cytoplasm during a process
called glycolysis.
• As glucose is broken down, some of its hydrogen
atoms are transferred to an electron acceptor called
NAD+. This forms an electron carrier called NADH.
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Chapter 5
Section 3 Cellular Respiration
NAD+ and NADH
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Chapter 5
Section 3 Cellular Respiration
Stage One: Breakdown of Glucose, continued
Glycolysis
• Glycolysis occurs in four steps:
Step 1 Phosphate groups from two ATP molecules are
transferred to a glucose molecule.
Step 2 The resulting six-carbon compound is broken down to
two three-carbon compounds.
Step 3 Two NADH molecules are produced, and each
compound gains one more phosphate group.
Step 4 Each three-carbon compound is converted to a threecarbon pyruvate, producing four ATP molecules in the
process.
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Chapter 5
Section 3 Cellular Respiration
Glycolysis
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Chapter 5
Section 3 Cellular Respiration
Glycolysis
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Chapter 5
Section 3 Cellular Respiration
Stage Two: Production of ATP
• When oxygen is present, pyruvate produced during
glycolysis enters a mitochondrion and is converted to
a two-carbon compound.
• This reaction produces one carbon dioxide molecule,
one NADH molecule, and one two-carbon acetyl
group.
• The acetyl group is attached to a molecule called
coenzyme A (CoA), forming a compound called
acetyl-CoA.
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Chapter 5
Section 3 Cellular Respiration
Stage Two: Production of ATP, continued
Krebs Cycle
• Acetyl-CoA enters a series of enzyme-assisted reactions
called the Krebs cycle, which follows five steps:
Step 1 Acetyl-CoA combines with a four-carbon
compound, forming a six-carbon compound and releasing
coenzyme A.
Step 2 Carbon dioxide is released from the six-carbon
compound, forming a five-carbon compound. Electrons
are transferred to NAD+, making a molecule of NADH.
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Chapter 5
Section 3 Cellular Respiration
Stage Two: Production of ATP, continued
Krebs Cycle
Step 3 Carbon dioxide is released from the compound. A
molecule of ATP and a molecule of NADH are made.
Step 4 The existing four-carbon compound is converted to a
new four-carbon compound. Electrons are transferred to an
electron acceptor called FAD, making a molecule of FADH2,
another type of electron carrier.
Step 5 The new four-carbon compound is then converted to the
four-carbon compound that began the cycle. Another molecule
of NADH is produced.
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Chapter 5
Section 3 Cellular Respiration
Krebs Cycle
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Chapter 5
Section 3 Cellular Respiration
Krebs Cycle
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Chapter 5
Section 3 Cellular Respiration
FAD and FADH2
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Chapter 5
Section 3 Cellular Respiration
Stage Two: Production of ATP, continued
Electron Transport Train
• In aerobic respiration, electrons donated by NADH
and FADH2 pass through an electron transport chain.
• In eukaryotic cells, the electron transport chain is
located in the inner membranes of mitochondria.
• At the end of the electron transport chain, hydrogen
ions and spent electrons combine with oxygen
molecules forming water molecules.
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Chapter 5
Section 3 Cellular Respiration
Electron Transport Chain of Aerobic
Respiration
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Chapter 5
Section 3 Cellular Respiration
Respiration in the Absence of Oxygen
• When oxygen is not present, NAD+ is recycled in
another way. Under anaerobic conditions, electrons
carried by NADH are transferred to pyruvate
produced during glycolysis.
• This process recycles NAD+ needed to continue
making ATP through glycolysis.
• The recycling of NAD+ using an organic hydrogen
acceptor is called fermentation.
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Chapter 5
Section 3 Cellular Respiration
Fermentation
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Chapter 5
Section 3 Cellular Respiration
Respiration in the Absence of Oxygen,
continued
Lactic Acid Fermentation
• In some organisms, a three-carbon pyruvate is
converted to a three-carbon lactate through lactic
acid fermentation.
• Fermentation enables glycolysis to continue
producing ATP in muscles as long as the glucose
supply lasts.
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Chapter 5
Section 3 Cellular Respiration
Respiration in the Absence of Oxygen,
continued
Alcoholic Fermentation
• In some organisms, the three-carbon pyruvate is
broken down to ethanol (ethyl alcohol), a two-carbon
compound, through alcoholic fermentation.
• As in lactic acid fermentation, NAD+ is recycled, and
glycolysis can continue to produce ATP.
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Chapter 5
Section 3 Cellular Respiration
Respiration in the Absence of Oxygen,
continued
Lactic Acid and Alcoholic Fermentation
• When oxygen is not present, cells recycle NAD+
through fermentation.
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Chapter 5
Section 3 Cellular Respiration
Respiration in the Absence of Oxygen,
continued
Production of ATP
• When oxygen is present, aerobic respiration occurs to produce
ATP. When oxygen is not present, fermentation occurs instead.
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Chapter 5
Section 3 Cellular Respiration
Cellular Respiration Versus Fermentation
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Chapter 5
Section 3 Cellular Respiration
Comparing Aerobic and Anaerobic Respiration
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Chapter 5
Standardized Test Prep
Multiple Choice
The chart below shows data on photosynthesis in one
type of plant. Use the chart to answer questions 1–3.
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Chapter 5
Standardized Test Prep
Multiple Choice, continued
1. Which statement is supported by the data?
A. Photosynthesis does not occur at 0°C.
B. The optimum temperature for photosynthesis is
approximately 46°C.
C. The rate of photosynthesis at 40°C is greater
than the rate at 20°C.
D. The rate of photosynthesis increases as
temperature increases from 25°C to 30°C.
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Chapter 5
Standardized Test Prep
Multiple Choice, continued
1. Which statement is supported by the data?
A. Photosynthesis does not occur at 0°C.
B. The optimum temperature for photosynthesis is
approximately 46°C.
C. The rate of photosynthesis at 40°C is greater
than the rate at 20°C.
D. The rate of photosynthesis increases as
temperature increases from 25°C to 30°C.
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Chapter 5
Standardized Test Prep
Multiple Choice, continued
2. At approximately what temperature is the plant
producing oxygen at the greatest rate?
F.
G.
H.
J.
0°C
23°C
46°C
50°C
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Chapter 5
Standardized Test Prep
Multiple Choice, continued
2. At approximately what temperature is the plant
producing oxygen at the greatest rate?
F.
G.
H.
J.
0°C
23°C
46°C
50°C
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Chapter 5
Standardized Test Prep
Multiple Choice, continued
3. Data obtained from a different type of plant show a
similar relationship between rate of photosynthesis
and temperature, but the curve is shifted to the right.
What environment would this plant be best adapted
to?
A.
B.
C.
D.
Cold subarctic environment
Cool, wet environment
Mild, dry environment
Hot equatorial environment
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Chapter 5
Standardized Test Prep
Multiple Choice, continued
3. Data obtained from a different type of plant show a
similar relationship between rate of photosynthesis
and temperature, but the curve is shifted to the right.
What environment would this plant be best adapted
to?
A.
B.
C.
D.
Cold subarctic environment
Cool, wet environment
Mild, dry environment
Hot equatorial environment
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