Download Photosynthesis

Objectives: Summarize how energy is captured from
sunlight in the first stage of photosynthesis.
Identify three environmental factors that
affect the rate of photosynthesis.
Plants, algae, some bacteria
Capture ~1% of energy from sunlight that reaches
Earth
Convert this to chemical energy
Happens in three stages
1) Energy is captured from sunlight
2) Light energy converted to chemical energy
3) Chemical energy stored in ATP/NADPH powers
formation of organic compounds
Using light, plants transform CO2 and water
into carbohydrates and release oxygen
WHERE????
Carbon
dioxide
WATER
_____________ + ____________
6 CO2 + ____________
6 H2O
_____________
Sugars + ____________
Oxygen
__________________
→
C6H12O6 + ____________
6 O2
_______________
6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2
Required for photosynthesis
Found in chloroplasts
Chlorophyll**
**Primary light-absorbing pigment in autotrophs
Carotenoids
Yellow, Orange, Red
Different wavelengths of light have
different colors
Different pigments absorb different
wavelengths
Color of light SEEN is the color NOT
absorbed
Light
Reflected
Light
Absorbed
light
Transmitted
light
Chloroplast
GREEN leaves have BOTH chlorophyll
AND carotenoids
ALL THE TIME
__________________
but the huge amount of chlorophyll
hides
______
the other colors and
leaves usually
look green
In FALL, chlorophyll production slows as
the trees shut down and photosynthesis
stops for winter.
Then we can see the
carotinoid colors that are usually hidden
by chlorophyll.
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There are two types of chlorophyll:
Chlorophyll a & Chlorophyll b
Absorption of Light by
Chlorophyll a and Chlorophyll b
Chlorophyll a
absorbs the
red & ________
violet
_____
wavelengths best.
Chlorophyll b
Chlorophyll a
red
It absorbs very
Blue light.
little ______
© Pearson Education, Inc. Publishing asPearson Prentice-Hall. All rights reserved.
Absorption of Light by
Chlorophyll a and Chlorophyll b
Chlorophyll b
Chlorophyll a
red
NEITHER KIND OF
CHLOROPHYLL IS
VERY GOOD AT
ABSORBING
GREEN LIGHT!
_________
Light hits thylakoids
Excites electrons
Water molecules fall apart
Oxygen is released into air
Hydrogen leaves behind ion
Excited electrons travel down the electron
transport chain (ETC)
H+ ions travel out of thylakoid
Create ATP (ADP + Pi)
OUTSIDE THYLAKOID:
Electrons + H join NADP to make NADPH
NADPH – provides electrons needed in step 3
a. Overall input:
light energy, H2O
b. Overall output:
ATP, NADPH, O2
http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120072/bio13.s
wf::Photosynthetic Electron Transport and ATP Synthesis
Light Independent Reactions
A.K.A. Calvin Cycle or
Dark Reactions
In Stroma
CO2 splits
C + O + H (transported
by NADPH) form
glucose (C6H12O6)
Energy from ATP is
used to form new
bonds
a. Overall input:
CO2, ATP, NADPH
b. Overall output:
glucose (after 2 full cycles)
• Lack of sufficient water can cause
photosynthesis to SLOW or STOP
• How does a cactus prevent this?
•Enzymes work best at specific temperatures
•0-35 °C
•Temp too low/high will cause photosynthesis to
SLOW or STOP
•Conifers???
•More light increases rate of photosynthesis
•Up to certain point, until plant reaches max rate
Compose a children’s story, song, or poem
about the travels of an electron through
the light reactions.
Be sure to represent ALL the elements of
the light reactions in your story.
Illustrate a scene from your story which
will best represent the activity during the
light reactions.
Attach your story to your illustration.
Question
Research?
Hypothesis
Procedures
Results/Data Analysis
Conclusions