Download Photosynthesis Using Light to Make Food

Photosynthesis
Using Light Energy to
Make Food
Photosynthesis

Plants use energy
to change carbon
dioxide and water
into glucose and
oxygen (waste
product)
Who performs Photosynthesis?
 Plants
and a few bacteria
 These are called autotrophs

Three major events take place in two
stages:
– Absorption of light energy
– Conversion of light energy into
chemical energy (ATP and NADPH)
– Storage of energy in the form of
carbohydrates
Where does it
happen?

Chloroplasts:
– Thylakoids (a single
pancake)
 Contain chlorophyll
– Grana (stacks)
 Granum is one stack.
– Stroma (thick fluid that
surrounds the grana)
omega.dawsoncollege.qc.ca/ ray/cell/401cell.htm


Light Dependent
Reaction
– Temperature
independent
– Light Reaction
Light Independent
Reaction
– Calvin-Benson Cycle
– Dark Reaction
www.emc.maricopa.edu/faculty/ farabee/BIOBK/BioBookPS.html
Light Reaction



Requires direct light energy
Occurs in the thylakoids of chloroplasts
2 steps occur here:
1. Absorption of light by pigments
2. Splitting of water
Electron carriers



Light dependent reaction
They gain tons of energy!
Cells use electron carriers to transport this
energy to other molecules
–

Called electron transport (name of process)
2 types in photosynthesis
–
NADP+


–
Carriers 2 high energy electrons and hydrogen ions
Create NADPH
ATP
Light Dependent Reaction
(depends on light)
Inputs=sun and water
 Products formed
– Oxygen gas-formed by splitting water
– Electrons transported to create
NADPH and ATP

 used
in the Calvin-Benson cycle
Calvin Cycle

Occurs in the stroma (filler in chloroplasts)

Also called the dark reaction
–

Carbon dioxide is the input and the
NADPH and ATP from the light reaction
The output is glucose
–
–
It is used for food and energy.
Formula for glucose
 C6H12O6
The Equation
Sunlight+ 6CO2
+ 6H20
----> C6H12O6 + 6 02
Factors that effect the rate of
photosynthesis

Temperature

Enzymes are important for photosynthesis to
work.
–
–

Light intensity
–


Enzymes work best in certain temperatures.
If the temp is too low or too high, it can decrease it or stop
photosynthesis.
Increase light will increase photosynthesis to a point.
Amount of Carbon Dioxide
Amount of water

http://www.brainpop.com/science/cellularlifean
dgenetics/photosynthesis/

Username: cebrainpop
Password: tiger1
