Transcript PHOTOSYNTHESIS & RESPIRATION

PHOTOSYNTHESIS
What do you know?
What do you want to know?
Photosynthesis uses sun energy to
make sugar (glucose) (
– Plants and algae only
– Autotrophs- make their own food
– Heterotrophs- can’t make their own food
All living organisms ( including plants)
use cellular respiration to get energy
from their food
Photosynthesis EQUATION
Sunlight+6CO2+ 6H20 C6H12O6 + __O2
Reactants- light , carbon dioxide, &
water
Products: sugar and oxygen
Light & Pigments
•Sunlight is “white” but
contains mixtures of visible
wavelengths
•Chlorophyll is a PIGMENT
in the chloroplast of the
plant cell that absorbs light
- Leaves absorb blue-violet & red-orange light
very well
- Green light is reflected- why plants look green!
Types of Pigments
Chlorophyll a
- Absorbs all colors of light
except green
- Plays major role in light
reactions of
photosynthesis
Chlorophyll b
- Appears yellow-green
Major
Pigments
- Absorbs additional light
Xanthophyll
-Yellow pigment
Carotene
-Red & orange pigments
Minor
Pigments
LOCATION OF PHOTOSYNTHESIS
Chloroplasts organelle in plant cells
CHLOROPLAST STRUCTURE
** Chloroplast has double membrane **
Thylakoids: sac-like photosynthetic
membranes
– Arranged in stacks called GRANA
– Have chlorophyll and other pigments
Stroma: Fluid area surrounding
thylakoids
Boozeman 5:00 Minutes
* Light-Dependent:
takes place in
thylakoids* Calvin Cycle:
takes place in
stroma
Light Reaction
1. Chlorophyll molecules in
thylakoid capture light
energy
2. This energy releases
electrons from H2O
3. H2O then splits into O2 and H+
4. Oxygen is a "waste product"
& escapes to the atmosphere
Light Reaction
So what happens to the electrons and
hydrogen ions?
• Chloroplasts use them to make an
energy-rich molecule called NADPH
and ATP
• The overall result of the light reaction?
Light + H20
Oxygen + NADPH +
ATP
Light reaction is charging up the
“battery” needed to synthesize sugars
in Calvin Cycle
- ADP and NADP+ recycle
Calvin Cycle
• Does NOT use light at
all
• Can use energy that
was made in light
cycle to form sugar
The Calvin Cycle
1. Occurs in the STROMA.
2. Uses CO2 and energy powered by ATP and
NADPH to produce sugar
3. NAPDH and ATP are recycled back to the
Light Cycle for “recharging”
Reactants:
Products:
Two Processes
Light Reaction
Calvin Cycle
Online Activity 8.1Animation of Light and Dark Cycles
Page 6 –Start
Factors Affecting Photosynthesis
• Temperature
• Light intensity
Carbon Cycle