Transcript The Working Cell: Energy from Sunlight

The Working Cell:
Energy from Sunlight
Chapter 8 Notes
Ch. 8 The Working Cell:
Energy from Light
8.1 Photosynthesis uses light energy
to make food.
8.2 The light reactions convert light
energy to chemical energy.
8.3 The Calvin cycle makes sugar
from carbon dioxide.
8.4 Photosynthesis has a global
impact.
8.1 Photosynthesis uses light
energy to make food.
Objectives
Describe the structure of a
chloroplast.
Identify the overall reactants and
products of photosynthesis.
8.1 Photosynthesis uses light
energy to make food.
Key Terms
Chloroplast
Chlorophyll
Stroma
Thylakoid
Light reactions
Calvin cycle
8.1 Photosynthesis uses light
energy to make food.
 Photosynthesis is the process by which
plants & other producers convert energy
of sunlight to energy stored in organic
molecules.
Chloroplast – organelle where
photosynthesis takes place
Chlorophyll – chemical that gives a
green color to chloroplasts.
8.1 Photosynthesis uses light
energy to make food.
Chloroplasts structure is key to its
function
Has an inner & outer membrane
Inner membrane encloses a thick fluid
called the stroma
Suspended in the stroma are
thylakoids – disk-shaped sacs
8.1 Photosynthesis uses light
energy to make food.
 Cellular respiration – fall of electrons
form glucose to oxygen gives off
energy, which is then used to make ATP.
 Photosynthesis is the opposite –
electrons from water are boosted uphill
by the energy from sunlight.
8.1 Photosynthesis uses light
energy to make food.
Excited electrons along with carbon
dioxide & water are used by
chloroplasts to produce glucose &
oxygen.
8.1 Photosynthesis uses light
energy to make food.
 Photosynthesis occurs in 2 main stages.
Light reactions – convert sunlight to
chemical energy
Stored in NADPH & ATP
Calvin cycle – makes sugar from
carbon dioxide and H+ ions from the
splitting of water.
8.1 Concept check (QUIZ)
 Draw & label a simple diagram of a
chloroplast that includes the following
structures: outer & inner membranes,
stroma, thylakoids.
 What are the reactants of
photosynthesis, what are the products?
 Name the 2 main stages of
photosynthesis. How are they related?
8.2 The light reactions convert
light energy to chemical energy
Objectives
Explain how light interacts with
pigments.
Describe how photosystems help
harvest light energy.
Identify the chemical products of the
light reactions.
8.2 The light reactions convert
light energy to chemical energy
Key Terms
Wavelength
Electromagnetic spectrum
Pigment
Paper chromatography
photosystem
8.2 The light reactions convert
light energy to chemical energy
 Light energy is a form of
electromagnetic energy
 Travels in waves (similar to ocean
waves)
Measured by wavelength – distance
between 2 adjacent waves.
8.2 The light reactions convert
light energy to chemical energy
 Different forms of electromagnetic
energy have characteristic wavelengths
Electromagnetic spectrum – the range
of types of electromagnetic energy
8.2 The light reactions convert
light energy to chemical energy
Pigments – chemical compounds that
give a substance its color.
 Cause different wavelengths to be…
 Absorbed
 Transmitted
 Reflected
8.2 The light reactions convert
light energy to chemical energy
Paper chromatography – lab technique
used to observe different pigments in
substances.
8.2 The light reactions convert
light energy to chemical energy
Harvesting light energy
Photosystems – clusters of pigment
molecules
Chlorophyll a
Chlorophyll b
Carotenoids
8.2 The light reactions convert
light energy to chemical energy
Harvesting light energy
1)Pigments absorb light energy
2)transfer energy to electrons
3)transfer energy to electronacceptor.
4)converts to ATP or NADPH.
8.2 The light reactions convert
light energy to chemical energy
Chemical products of the light reactions
Oxygen, released as a waste product
of the 1st photosystem.
ATP – produced by the release of
energy by the electron transport chain
between photosystems.
NADPH – produced by the second
photosystem
8.2 Concept check
Explain why a leaf appears green.
Describe what happens when a
molecule of chlorophyll a absorbs light.
Besides oxygen, what 2 molecules are
produced by the light reactions?
Where in the chloroplast do the light
reactions take place?
8.3 The Calvin cycle makes
sugar from carbon dioxide
Objectives
Explain how the Calvin cycle makes
sugar.
Summarize the overall process of
photosynthesis.
8.3 The Calvin cycle makes
sugar from carbon dioxide
 The Calvin cycle
 Called
a cycle because the starting
material RuBP is regenerated each
time the process occurs
 RuBP is a 5 carbon sugar
8.3 The Calvin cycle makes
sugar from carbon dioxide
 Into
the Calvin cycle
 Carbon dioxide
From air
 ATP
From light reactions
 NADPH
8.3 The Calvin cycle makes
sugar from carbon dioxide
 Outputs
of Calvin cycle
 G3P (an energy rich sugar)
–Not yet glucose
–Used by plant to make glucose
 ADP + P
 NADP+
8.3 The Calvin cycle makes
sugar from carbon dioxide
 Summary of photosynthesis
 Light
reactions
 Convert light energy to chemical
energy
 Occurs in thylakoids
 Uses water (reactant) & releases
oxygen (product)
8.3 The Calvin cycle makes
sugar from carbon dioxide
 Calvin
cycle
 Occurs in stroma
 Uses ATP & NADPH
 Converts carbon dioxide (reactant)
to sugar (product)
8.3 Concept check
 What are the inputs & outputs of the
Calvin cycle?
 Which stage of photosynthesis uses
each reactant from the overall
photosynthesis equation? Which stage
generates each product from the overall
photosynthesis equation?
8.3 Concept check
 Why is the Calvin cycle called a cycle?
 What molecule is the direct product of
photosynthesis? How is that molecule
then used by the plant cell?
8.4 Photosynthesis has a global
impact.
 Objectives
 Describe
the path of carbon in the
carbon cycle.
 Explain
how photosynthesis is related
to climate.
8.4 Photosynthesis has a global
impact.
 Key Terms
 Carbon
cycle
 Greenhouse effect
8.4 Photosynthesis has a global
impact.
 Processes that occur on a global scale
depend on chloroplasts & mitochondrion
 Carbon cycle – process by which
carbon moves from inorganic to
organic & back to inorganic.
8.4 Photosynthesis has a global
impact.

Path of carbon in the carbon cycle
1) Producers convert inorganic carbon to
organic carbon through
photosynthesis.
2) Consumers eat the producers, may be
eaten by other consumers.
3) Cellular respiration by both producers
& consumers eventually carbon
dioxide to the atmosphere
8.4 Photosynthesis has a global
impact.
 Plants & other photosynthetic
organisms make about 160 billion
metric tons of organic material.
 80 trillion copies of book
 25 stacks reaching to the sun.
8.4 Photosynthesis has a global
impact.
 Carbon dioxide in the atmosphere traps
in heat – greenhouse effect
 Keeps world climate warm enough for
living things.
 Average 10°C warmer than it would
be.
 Amount of carbon dioxide in
atmosphere is rising.
Photosynthesis
Stages of Photosynthesis
Electromagnetic spectrum
Pigments & Color
Harvesting Light Energy
Chemical products
of light reactions
Calvin cycle
Photosynthesis
Greenhouse effect
Light Waves