I. Photosynthesis: Light is important to plants
II. Properties of Light
X-ray---UV--380nm-------------------------760nm---IR---TV appears black violet blue green yellow orange red black tanning heat lamps (nanometer - nm = 1 billionth of a meter)
3. As wavelength increases, energy per photon decreases. Photons of violet
light have more energy than photons of red light
NOTE: A photon (as discussed here) is different from a
photon torpedo.
III. Pigments
B. Absorption
spectrum - how much light of each wavelength is absorbed by a particular
pigment - see right ---> [from MIT's Photosynthesis Hypertextbook]
C. Action spectrum - how much of a physiological process occurs at each particular wavelength of light
B. Definition - synthesis of organic compounds from water and carbon dioxide
using energy absorbed by pigments from sunlight
6 CO2 + 12 H2O ----------> C6H12O6 + 6 02 + 6 H2O ^ sugar light (glucose) pigments enzymes
C.Chloroplasts - in eukaryotic cells
granum w/chlorophyll (round stacks of plates) stroma w/enzymes for Calvin (jello) double membrane
1) ADP + Pi + energy <-> ATP adenosine inorganic diphosphate phosphate
2) NADP+ + 2e- + 2H+ <-> NADPH2 + H+ (nicotinamide adenine dinucleotide phosphate)
b. OVERALL - use of light energy to generate two high-energy compounds, ATP
and NADPH2
2) NADPH2
3) The lost electrons in chlorophyll are replaced from electrons of oxygen
in water; When e- are removed from water, oxygen is produced as a by-product
of photosynthesis, water is split -> 2H+ (protons) + 2e- + 1/2
O2 (gas)
(Note - NADP+ + 2e- + 2H+ <-> NADPH2)
2. Dark reactions (Calvin Cycle or light independent reactions), in stroma of chloroplasts - occur same time as light reaction but does not require light
6CO2 + 12NADPH2 + 18ATP ---> 1 C6H12O6 + 12NADP + 18ADP + 18Pi + 6H2O ^ glucose enzymes
E. Summary of some key points in photosynthesis
Why Study
Photosynthesis: An essay on the significance of photosynthesis on living
organism, especially humans
Photosynthesis
from Newton's Apple
Photosynthesis:
An excellent review
Photosynthetic
Antennas: Advanced information
How
a rainbow is formed
The Light
Reaction: Detailed but most useful
The Dark
Reaction: Detailed but most useful
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Last revised :Aug 11, 1998, Straney