Photosynthesis
Chapter 8
Vocabulary—Breaking Down the Definitions
• Photosynthesis
• Pigment
• Chlorophyll
• Thylakoid
• Stroma
• NADP+
• Light Dependent Reactions
• ATP Synthase
• Calvin Cycle
Photosynthesis—What Do We Already Know?
Photosynthesis Brain Pop
6
Chemical Equation—Quiz on this Next
Meeting!
6
Photosynthesis
•Photosynthesis uses the
energy of sunlight to convert
water and carbon dioxide
into oxygen and high-energy
sugars.
Light and Pigments
•In addition to water and carbon dioxide,
photosynthesis also requires LIGHT and
CHLOROPHYLL.
•CHLOROPHYLL= a molecule within a
chloroplast
•Chlorophyll is a pigment that absorbs
light
IVF to Analyze
the Graph!
2 Stages of Photosynthesis
Light Reactions—In the Thylakoids
•Light Energy (from the sun) is converted to
chemical energy, which is temporarily stored in
ATP and the energy carrier molecule NADPH.
Calvin Cycle—In the Stroma
•A series of enzyme-assisted chemical reactions
that produces a three-carbon sugar.
Inside a Chloroplast
• Photosynthesis takes place inside a chloroplast
• The chloroplast contains saclike membranes called
THYLAKOIDS
• THYLAKOIDS are arranged in stacks called GRANA
• The Chlorophyll is inside the thylakoids
• The STROMA is the region outside of the thylakoids
Light Reactions
1.The first stage of photosynthesis is the
LIGHT REACTIONS.
2.Light is absorbed by the chloroplasts
3.Light Energy is converted to Chemical
Energy (stored in ATP and NADPH)
Light Reactions Continued
4. Oxygen is given off during this
reaction. --Leaf Demo-5.Chlorophyll in the chloroplast contains
pigments (compounds that absorb
light) that absorb a lot of blue and red
light but reflect green light (giving
plants their green color.
Light Reactions Continued
6. An oxidation reaction takes place, losing
electrons and the primary electron
acceptor takes on the lost electrons in a
reduction reaction.
7. The primary electron acceptor donates
the electrons to a series of molecules in
the thylakoid membrane of the
chloroplast.
Oxygen as Byproduct Demo
Label
the
diagram
Dark Reactions/Calvin Cycle
•In the second set of reactions in
photosynthesis plants use the energy that
was stored in ATP and NADPH during the
light reactions to produce sugars.
•Most common way this is done is called the
CALVIN CYCLE.
•Calvin Cycle Song!
4 Steps of the Calvin Cycle
•3 CO2 molecules diffuse into the stroma and
Step combine with a 5-Carbon molecule, RuBP.
1
This molecule is very unstable and it quickly
splits into 2 3-Carbon molecules called 3PGA.
•Each 3-PGA is converted into another 3
Step Carbon molecule, G3P after receiving a
2
phosphate group from ATP and a proton
from NADPH.
4 Steps of the Calvin Cycle
•One of the G3P molecules leave the Calvin
Step Cycle to make carbohydrates which are
3
stored for later use.
•The remaining 3GP molecules are converted
back
into
RuBP
by
adding
phosphate
groups
Step
4
from ATP and then the Calvin Cycle begins
again.
Step 4– The rest of the G3P is
converted back into RuBP/Rubisco
Calvin Cycle
Step 3– One molecule of G3P leaves
the cycle to make sugars
Step 1—3 CO2 molecules combine to
form RuBP (6 carbon molecule)
which splits into 3 PGA
Step 2—Each molecule of 3 PGA is
converted to G3P
Factors Affecting Photosynthesis
•Water, Temperature, Intensity of Light all
affect the rate of photosynthesis
Thinking Visually
• Complete the flowchart on page 216 of your book.
Investigation Photosynthesis