Photosynthesis
• Strategy for survival to obtain energy to do
work used by plants, protists, and some
bacteria!
• Def: process of obtaining energy from the sun
to convert carbon dioxide & water into sugar
PHOTOSYNTHESIS
What do you need for
Photosynthesis?
What do you need for
PHOTOSYNTHESIS?
The sun
Carbon dioxide
from the air
Pigment
Water from the
soil
Carbon Dioxide
• How does gases enter and leave a plant?
Stoma
or
Stomate
or
Stomata
Sun = Source of Light
• Consists of Waves
• Length of Wave determines light color.
• Light absorbing substances are called
pigments.
Types of Pigments
•
Chlorophyll a & b (look green)
–
–
Absorb violet/blue light & orange/red light but not
green light!
The color we observe is the color that is not absorbed
by the pigment but reflected and that is why we see it!
More on Pigments!
• Carotenoids (look orange or red)
– Absorb light not able to be captured by chlorophyll
– Help the plant to capture more light.
– Accessory Pigment
• Pigments are considered enzymes in photosynthesis
because they are not changed, are reusable, and help
the reaction to occur!
(Usually are not shown in the photosynthetic equation or they are placed
over the arrow!)
Pigments are contained
in the Chloroplasts!
vacuole
Cell wall
nucleus
Cell
membrane
Chloroplasts!!
Plant Cell
Chloroplast Structure
– Thylakoids: flattened sacs that contain pigment
– Grana: stacks of thylakoids
– Stroma: fluid filled space around grana &
thylakoids
PHOTOSYNTHESIS
What does photosynthesis
make?
PHOTOSYNTHESIS
Oxygen
(waste)
Food for
plant (sugar)
The sun
PHOTOSYNTHESIS
Oxygen
(waste)
Carbon dioxide
from the air
Food for plant
(sugar)
Water from the
soil
PHOTOSYNTHESIS:
Equation
Sugar +Oxygen
Water +Carbon dioxide
Pigment
6 H2O + 6 CO2  C6H12O6 + 6O2
Photosynthesis Stages
Light Reactions
• Step 1 (occurs first)
• Location – Thylakoid of
Chloroplast
• Absorbs & Converts
visible light into
chemical energy that
then powers the Calvin
Cycle
Calvin Cycle
• Step 2 (occurs second)
• Aka
– Dark Reactions
– Light Independent Reactions
• Location – Stroma of
Chloroplast
• Uses the energy from the
light reactions to convert
CO2 into sugar