Chemical Energy and the ATP Cycle
ATP Overview
• Molecules store chemical energy in their bonds.
• Organisms can convert chemical energy from food into ATP.
• ATP : the chemical energy used for most cell processes
• Organisms break down organic molecules to produce ATP.
• Carbohydrates are frequently broken down for ATP production (Carbs: immediate energy source)
• up to 38 ATP from one glucose molecule
ATP Structure
• ATP : adenosine triphosphate
• Adenosine is composed of adenine and ribose.
• A large amount of energy is stored in the bonds that hold the 3 phosphate groups (triphosphate) together.
• When one phosphate group is broken off, energy is released from the broken bond.
• Only two phosphate groups remain (diphosphate)
• The molecule is now called Adenosine diphosphate (ADP)
ATP Cycle
Chloroplast Structure
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Photosynthesis: the process of
converting solar energy (sunlight) into
chemical energy (glucose)
Producers: organisms that produce
(make) their own source of chemical
energy.
– Plants, some bacteria, and some
protists use photosynthesis and
are producers.
– Producers are autotrophs.
– Consumers are heterotrophs
Photosynthesis takes place in the
chloroplast.
– all eukaryotic photosynthetic
producers have this organelle
Chlorophyll is a pigment molecule that
absorbs light energy.
– In plants, chlorophyll is found in chloroplasts.
– It makes plants appear green.
Colors of light can either be reflected or absorbed.
– green light is reflected
– most other colors are absorbed
Overview of Photosynthesis:
6 CO2 + 6 H2O + sunlight ➝➝➝➝➝➝ C6H12O6 + 6 O2
Electron Carriers
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NADP+ and NADPH are electron carriers used in photosynthesis.
– called NADP+ when it is not carrying electrons
– called NADPH when it is carrying electrons
Light-Dependent Reactions
Light-Independent Reactions
thylakoid membranes of the chloroplast
Location
stroma of the chloroplast
to make ATP and NADPH (an electron
carrier)
Purpose
to make sugars (carbohydrates), such
as glucose (C6H12O6)
Reactants
Products
Check Your Knowledge
1. Where in the chloroplast do the
light-dependent reactions take place?
8. Which two reactants are needed for the
light-dependent reactions? (circle two)
NADPH
oxygen
2. Where in the chloroplast do the
light-independent reactions take place?
energy-carrying molecule
oxygen
4. What is the final product of the Calvin Cycle?
5. What two molecules provide the energy and
electrons for the Calvin cycle?
water
9. Which two reactants are needed for Calvin
Cycle? (circle two)
carbon dioxide
3. What gas is used in the Calvin Cycle?
light
stroma
10. Which electron carrier is the high-energy
form (contains electrons)? (circle one)
NADPH
NADP+
11. For each statement, write LDR if it describes
the Light-Dependent Reactions or LIR if it
describes the Light-Independent Reactions.
_________ Use energy from the sun
_________ Take place in the stroma
_________ Use carbon dioxide
6. Where are the two molecules from Question
5 produced (where do they come from?)
_________ Take place in thylakoids
_________ Produce oxygen
_________ Require water
7. Which reactions convert the energy of
sunlight to energy-rich carriers? (circle one)
light-dependent reactions
light-independent reactions
_________ Produce sugars
_________ Also called Calvin cycle
_________ Convert ADP into ATP
8. Which two reactants are needed for the
light-dependent reactions? (circle two)
KEY
1. Where in the chloroplast do the
light-dependent reactions take place?
the thylakoids/thylakoid membranes of the
chloroplasts
2. Where in the chloroplast do the
light-independent reactions take place?
in the stroma of the chloroplasts
NADPH
oxygen
water
9. Which two reactants are needed for Calvin
Cycle? (circle two)
carbon dioxide
energy-carrying molecule
oxygen
3. What gas is used in the Calvin Cycle?
CO2
light
stroma
10. Which electron carrier is the high-energy
form (contains electrons)? (circle one)
NADPH
NADP+
4. What is the final product of the Calvin Cycle?
sugars
5. What two molecules provide the energy and
electrons for the Calvin cycle?
ATP (energy)
NADPH (electrons)
11. For each statement, write LDR if it describes
the Light-Dependent Reactions or LIR if it
describes the Light-Independent Reactions.
_________ Use energy from the sun LDR
_________ Take place in the stroma LIR
_________ Use carbon dioxide LIR
6. Where are the two molecules from Question
5 produced (where do they come from?)
They come from the Light-Dependent
Reactions in the thylakoid membranes
_________ Take place in thylakoids LDR
_________ Produce oxygen LDR
_________ Require water LDR
7. Which reactions convert the energy of
sunlight to energy-rich carriers?
_________ Produce sugars LIR
light-dependent reactions
_________ Also called Calvin cycle LIR
light-independent reactions
_________ Convert ADP into ATP LDR