What Would Plants Look Like On Alien
Planets?
Why Would They Look Different?
 Different Stars Give off Different types of light or
Electromagnetic Waves
 The color of plants depends on the spectrum of the
star’s light, which astronomers can easily observe.
(Our Sun is a type “G” star.)
Anatomy of a Wave
 Wavelength
 Is the distance between the crests of waves
 Determines the type of electromagnetic energy
Electromagnetic Spectrum
 Is the entire range of electromagnetic energy, or
radiation
 The longer the wavelength the lower the energy
associated with the wave.
Visible Light
 Light is a form of electromagnetic energy, which
travels in waves
 When white light passes through a prism the
individual wavelengths are separated out.
Visible Light Spectrum
 Light travels in waves
 Light is a form of radiant energy
 Radiant energy is made of tiny packets of energy called
photons
 The red end of the spectrum has the lowest energy
(longer wavelength) while the blue end is the highest
energy (shorter wavelength).
 The order of visible light is ROY-G-BIV
 This is the same order you will see in a rainbow b/c
water droplets in the air act as tiny prisms
Chloroplast – Where the Magic
Happens!
+
H2 O
CO2
Energy
Which splits
water
ATP and
NADPH2
Light is Adsorbed
By
Chlorophyll
ADP
NADP
Chloroplast
O2
Light Reaction
Calvin Cycle
Used Energy and is
recycled.
+
C6H12O6
Dark Reaction
6 CO2 + 12 H2O + Light energy  C6H12O6 + 6 O2 + 6 H2 O
Light Options When It Strikes A Leaf
Light
 Reflect – a small amount of lightReflected
is reflected off of the
Light
leaf. MostChloroplast
leaves reflect the color green, which means
that it absorbs all of the other colors or wavelengths.
 Absorbed – most of the light is absorbed by plants
providing the energy needed for the production of
Glucose (photosynthesis)
 Transmitted – some light passes through the leaf
Absorbed
light
Granum
Transmitted
light
Figure 10.7
Photosynthesis Overview
Concept Map
Photosynthesis
includes
Light
independent
reactions
Light
dependent
reactions
uses
Light
Energy
Thylakoid
membranes
to produce
ATP
NADPH
occurs in
occur in
Stroma
of
O2
Chloroplasts
uses
ATP
NADPH
to produce
Glucose
Anatomy of a Leaf
Leaf cross section
Vein
Mesophyll
Stomata
Figure 10.3
CO2
O2
Chloroplast
Chloroplast
 Are located within the palisade layer of the leaf
 Stacks of membrane sacs called Thylakoids
 Contain pigments on the surface

Pigments absorb certain wavelenghts of light
 A Stack of Thylakoids is called a Granum
Mesophyll
Chloroplast
5 µm
Outer
membrane
Stroma Granum
Intermembrane
space
Thylakoid Thylakoid
space
Inner
membrane
1 µm
Pigments
 Are molecules that absorb light
 Chlorophyll, a green pigment, is the primary absorber
for photosynthesis
 There are two types of cholorophyll
 Chlorophyll a
 Chlorophyll b
 Carotenoids, yellow & orange pigments, are those that
produce fall colors. Lots of Vitamin A for your eyes!
 Chlorophyll is so abundant that the other pigments are
not visible so the plant is green…Then why do leaves
change color in the fall?
Color Change
 In the fall when the temperature drops plants stop
making Chrlorophyll and the Carotenoids and other
pigments are left over (that’s why leaves change color
in the fall).
 The absorption spectra of three types of pigments in
chloroplasts
Three different experiments helped reveal which wavelengths of light are photosynthetically
important. The results are shown below.
EXPERIMENT
RESULTS
Absorption of light by
chloroplast pigments
Chlorophyll a
Chlorophyll b
Carotenoids
Wavelength of light (nm)
(a) Absorption spectra. The three curves show the wavelengths of light best absorbed by
three types of chloroplast pigments.
Figure 10.9
Rate of photosynthesis
(measured by O2 release)
 The action spectrum of a pigment
 Profiles the relative effectiveness of different wavelengths
of radiation in driving photosynthesis
(b) Action spectrum. This graph plots the rate of photosynthesis versus wavelength.
The resulting action spectrum resembles the absorption spectrum for chlorophyll
a but does not match exactly (see part a). This is partly due to the absorption of light
by accessory pigments such as chlorophyll b and carotenoids.
 The action spectrum for photosynthesis
 Was first demonstrated by Theodor W. Engelmann
Aerobic bacteria
Filament
of alga
500
600
700
400
(c) Engelmann‘s experiment. In 1883, Theodor W. Engelmann illuminated a filamentous alga with light that had
been passed through a prism, exposing different segments of the alga to different wavelengths. He used aerobic
bacteria, which concentrate near an oxygen source, to determine which segments of the alga were releasing the
most O2 and thus photosynthesizing most.
Bacteria congregated in greatest numbers around the parts of the alga illuminated with violet-blue or red light.
Notice the close match of the bacterial distribution to the action spectrum in part b.
CONCLUSION
photosynthesis.
Light in the violet-blue and red portions of the spectrum are most effective in driving
Absorption of chlorophylls a and b
at various wavelengths in the
visible light spectrum
Pigment
 Molecules that absorb specific wavelengths of light
 Chlorophyll absorbs reds & blues and reflects green
 Xanthophyll absorbs red, blues, greens & reflects yellow
 Carotenoids reflect orange
Chlorophyll
 Green pigment in plants
 Traps sun’s energy
 Sunlight energizes electron in chlorophyll
PHOTOSYNTHESIS
 Comes from Greek Word “photo” meaning “Light” and
“syntithenai” meaning “to put together”
 Photosynthesis puts together sugar molecules using
water, carbon dioxide, & energy from light.
Happens in two phases
 Light-Dependent Reaction
 Converts light energy into chemical energy
 Light-Independent Reaction
 Produces simple sugars (glucose)
 General Equation
 6 CO2 + 6 H2O  C6H12O6 + 6 O2
First Phase
 Requires Light = Light Dependent Reaction
 Sun’s energy energizes an electron in chlorophyll
molecule
 Electron is passed to nearby protein molecules in the
thylakoid membrane of the chloroplast
Excitation of Chlorophyll by Light
 When a pigment absorbs light
 It goes from a ground state to an excited state, which is
unstable
e–
Excited
state
Heat
Photon
(fluorescence)
Photon
Figure 10.11 A
Chlorophyll
molecule
Ground
state



Photosystem II: Clusters of pigments boost eby absorbing light w/ wavelength of ~680 nm
Photosystem I: Clusters boost e- by absorbing
light w/ wavelength of ~760 nm.
Reaction Center: Both PS have it. Energy is
passed to a special Chlorophyll a molecule which
boosts an e-
 A mechanical analogy for the light reactions
e–
ATP
e–
e–
NADPH
e–
e–
e–
Mill
makes
ATP
e–
Figure 10.14
Photosystem II
Photosystem I
ATP
 Adenosine Triphosphate
 Stores energy in high energy bonds between
phosphates
NADPH
 Made from NADP+; electrons and hydrogen ions
 Made during light reaction
 Stores high energy electrons for use during light-
Independent reaction (Calvin Cycle)
H2O
CO2
Light
NADP 
ADP
+ P
LIGHT
REACTIONS
CALVIN
CYCLE
ATP
NADPH
Chloroplast
Figure 10.5
O2
[CH2O]
(sugar)
PART II
 LIGHT INDEPENDENT REACTION
 Also called the Calvin Cycle
 No Light Required
 Takes place in the stroma of the chloroplast
 Takes carbon dioxide & converts into sugar
 It is a cycle because it ends with a chemical used in the
first step
Begins & Ends
 The Calvin Cycle begins with the products of the light
reaction.
 (the Calvin Cycle uses ATP & NADPH)
 CO2 is added and ends in the production of sugar
(GLUCOSE)
 Formula: C6H12O6
 The Calvin cycle
H2 O
Light
CO2
Input
3 (Entering one
CO2 at a time)
NADP+
ADP
CALVIN
CYCLE
LIGHT
REACTION
ATP
Phase 1: Carbon fixation
NADPH
O2
Rubisco
[CH2O] (sugar)
3 P
3 P
P
Short-lived
intermediate
P
Ribulose bisphosphate
(RuBP)
P
6
3-Phosphoglycerate
6
ATP
6 ADP
CALVIN
CYCLE
3 ADP
3
ATP
Phase 3:
Regeneration of
the CO2 acceptor
(RuBP)
6 P
6 NADPH
6 NADPH+
6 P
P
5
(G3P)
6
P
Glyceraldehyde-3-phosphate
(G3P)
P
1
Figure 10.18
P
1,3-Bisphoglycerate
G3P
(a sugar)
Output
Glucose and
other organic
compounds
Phase 2:
Reduction
Chloroplast – Where the Magic
Happens!
+
H2 O
CO2
Energy
Which splits
water
ATP and
NADPH2
Light is Adsorbed
By
Chlorophyll
ADP
NADP
Chloroplast
O2
Light Reaction
Calvin Cycle
Used Energy and is
recycled.
+
C6H12O6
Dark Reaction
6 CO2 + 12 H2O + Light energy  C6H12O6 + 6 O2 + 6 H2 O
Cellular Respiration
How Cells Harvest Chemical Energy
Introduction to Cell Metabolism
Glycolysis
Aerobic Cell Respiration
Anaerobic Cell Respiration
Breathing and Cell Respiration are related
O2
BREATHING
CO2
Lungs
Muscle cells carrying
out
CO2
Bloodstream
O2
CELLULAR
RESPIRATION
Sugar + O2  ATP + CO2 + H2O
Cellular Respiration uses oxygen and glucose to produce
Carbon dioxide, water, and ATP.
Glucose
Oxygen gas
Carbon
dioxide
Water
Energy
How efficient is cell respiration?
Energy released
from glucose
(as heat and light)
Energy released
from glucose
banked in ATP
Gasoline energy
converted to
movement
About
40%
25%
100%
Burning glucose
in an experiment
“Burning” glucose
in cellular respiration
Burning gasoline
in an auto engine
Reduction and Oxidation
OILRIG
Oxidation is losing electrons
Reduction is gaining electrons
Loss of hydrogen atoms
Energy
Glucose
Gain of hydrogen atoms
Glucose gives off energy and is oxidized
General Outline
Glucose
Glycolysis
Oxygen
Aerobic
Transition Reaction
Krebs Cycle
ETS
36 ATP
No Oxygen
Anaerobic
Pyruvic Acid
Fermentation
Glycolysis
Where? The cytosol
What? Breaks down glucose to pyruvic acid
Glycolysis
Steps 1 – 3 A fuel
molecule is energized,
using ATP.
Glucose
Step
1
Glucose-6-phosphate
2
Fructose-6-phosphate
3
Energy In: 2 ATP
Fructose-1,6-diphosphate
Step 4 A six-carbon
intermediate splits into
two three-carbon
intermediates.
4
Glyceraldehyde-3-phosphate
(G3P)
5
Step 5 A redox
reaction generates
NADH.
6
Energy Out: 4 ATP
Steps 6 – 9 ATP
and pyruvic acid
are produced.
1,3-Diphosphoglyceric acid
(2 molecules)
7
3-Phosphoglyceric acid
(2 molecules)
8
2-Phosphoglyceric acid
(2 molecules)
2-Phosphoglyceric acid
(2 molecules)
NET 2 ATP
9
Pyruvic acid
(2 molecules
per glucose molecule)
General Outline of Aerobic Respiration
Glycolysis
Transition Reaction
Krebs Cycle
Electron Transport System
Transition Reaction
Each pyruvic acid molecule is broken down to form CO2 and a two-carbon
acetyl group, which enters the Krebs cycle
Pyruvic Acid
Acetyl CoA
General Outline of Aerobic Respiration
Glycolysis
Transition Reaction
Krebs Cycle
Electron Transport System
Krebs Cycle
Where? In the Mitochondria
What? Uses Acetyl Co-A to generate ATP, NADH,
FADH2, and CO2.
Krebs Cycle
Krebs Cycle
General Outline of Aerobic Respiration
Glycolysis
Krebs Cycle
Electron Transport System
Electron Transport System
Protein
complex
Intermembrane
Electron
space
carrier
Inner
mitochondrial
membrane
Electron
flow
Mitochondrial
matrix
ELECTRON TRANSPORT CHAIN
Figure 6.12
ATP
SYNTHASE
Electron Transport System
For each glucose molecule that enters cellular respiration, chemiosmosis
produces up to 38 ATP molecules
Overview of Aerobic Respiration
Fermentation
Requires NADH generated by glycolysis.
Where do you suppose these reactions take place?
Yeast produce carbon dioxide and ethanol
Muscle cells produce lactic acid
Only a few ATP are produced per glucose
Fermentation
Fermentation in the Absence of Oxygen
•Fermentation When
oxygen is not present,
fermentation follows
glycolysis, regenerating
NAD+ needed for glycolysis
to continue.
•Lactic Acid
Fermentation In lactic
acid fermentation, pyruvate
is converted to lactate.
 Each molecule of glucose can generate 36-38
molecules of ATP in aerobic respiration but only 2 ATP
molecules in respiration without oxygen (through
glycolysis and fermentation).