photosynthesis
DESCRIPTION
A powerpoint presentation on the light capturing reaction of photosynthesisTRANSCRIPT
An Overview of the Light Capturing Reaction of Photosynthesis
Prepared byJohn McCormick
August 21, 2009
The process of photosynthesis
The Basic Reaction
6CO2 + 6H2O C6H12O6 + 6O2
Sun
The Energy Source
Photons provide the energy necessary to drive photosynthesis
Photons:Are packets of energy
Have no massBehave as particles or wave
Electromagnetic Radiation
The smaller the wavelength the higher the energyλ Lamda is the symbol used for wavelengthf is the symbol for frequencyAs you move from left to right on the chart thewavelength gets longer and the frequency decreases
The structure of a Chloroplast
A Chloroplast:
• Is a double membrane organelle
•Chlorophyll is located in the thylakoids
•A stack of thylakoids is called a granum
•The light capturing reactions occurs in the thylakoids
There are two major forms of chlorophyll- Chlorophyll a
Chlorophyll b
Both molecules have a porphorin ring
Chlorophyll a and b both absorb lightEnergy from the visible end of the Electromagnetic spectrum
This is seen in an absorptionspectrum
The absorption spectrum shows:
Chlorophyll a and b absorb predominantly the red and blue wavelengths of light
Accessory pigments such as carotenoids absorb other wavelengths of light
When chlorophyll first absorbs a photon it becomes excited and:
Passes this electron e- to a primary
electron acceptor
This molecule then passes the electron down the electron transport chain
This results in the formation of ATP
This is seen here
A molecule of water is broken down to replace the electronsthat are lost in this process
H2O 2H+ + ½
Next, a photon of a different wavelength is absorbed by chlorophyll in Photosystem I and becomes excited.
This e- is passed to a primary electron acceptor.
The e- is then passed to
NADP+ an e- acceptor
NADP+ becomes reduced as a result
NADP+ has this structure
This is the entire Light Capturing reaction
Summary of the Light Capturing Reaction
ATP is generatedATP is generated
NADPH is producedNADPH is produced
Water is broken downWater is broken down
OO22 is generated is generated
Waiting on a Sunny Day provided by
To see animation of the entire process
http://www.cnr.vt.edu/DENDRO/forestbiology/photosynthesis.swf