Photosynthesis Flashcards
Photosynthesis
Light energy is used to make CO2 into organic molecules
Organic molecules
Anything with one or more C-H bond
Autotrophs
Compounds that don’t need anything from the environment
Photoautotrophs
Use energy from photons to be self sustaining
Chemoautotrophs
Autotrophs that do not use energy from the sun
Ecosystem lifestyle
Primary producers (Chemoautotrophs)– primary consumers– dead bodies–decomposers
Heterotrophs
Require premade energy to survive
Photosynthesis occurs in
Eukaryotes and bacteria but not archaea
Photosynthesis reaction
6CO2 + 12H2O– C6H12)6 + 6O2 + 6H20
Rate of photosynthesis
Measured by CO2 in or O2 out because of their equal molar masses
Redox of photosynthesis
CO2 is reduced to glucose, water is oxidezed into oxygen
2 photosynthetic processes
The light reaction and the Calvin cycle
The light reaction
Pigment captures light energy and makes NADPH and ATP. Electrons needed come from the oxidation of water
Calvin cycle
Energy in ATP and NADPH is used to make glucose. out of CO2. A reduction reaction called carbon or CO2 fixation occurs
All organic molecules
Are directly or indirectly products of photosynthesis
Photosynthesis location
The chloroplast
3 membranes of the chloroplast
Outer, inner, and intramembrane space
Outer membrane
Covers the outer surface of the chloroplast
Inner membrane
Just inside the outer membrane
Intramembrane space
Space between the 2 membranes
Stroma
Aqueous environment in the chloroplast
Thylakoids
3rd membrane in the stroma that form closed sacs filled with the thylakoid lumen
Light reaction location
Within the thylakoid membrane
Calvin cycle location
The stroma
Cyanobacteria
Photosynthesis iccurs in the plasma membrane. Shows that chloroplast is derived from free living cyanobacteria
How much CO2 is photosynthesized per year
1.1x 10^14 kg
What organisms do photosynthesis
1/2 of the work is done by phytoplankton. Lots in the poles because of the nutrient rich waters
Iron
An enzyme cofactor fot the ETC that is crutial for photosynthesis.
Increasing iron
In the ocean would increase phytoplankton and decrease climate change
Photosynthetic apparatus
Proteins in the thylakiod membrane responsible for light reactions. On these are pigment molecules that absorb light
Photosystem
The combination of photosynthetic apparatus and pigment molecules
Light and matter interactions
Photons or quanta. Not waves.
Photons contain energy that
Is inverse to its wavelength
3 outcomes after a photon is absorbed
Florescence, energy transfer electron transfer
Florescence
An excited electron returns to ground state releasing heat or light with a longer wavelength
Energy transfer
Energy but not electron is transferred and excited a neighboring electron. Very energy efficient
Electron transfer
Transferred to near by accepting molecule
Light absorbing molecules
Chlorophyll and carotenoid
Chlorophyll
Absorbs green pigment, Chlorophyll a and b are the most dominant. They have different absorption spectrums
Absorption spectrum
A plot of absorption vs wavelength made from a spectrophotometer.
Chlorophyll a
Absorbs blue and red light
Chlorophyll b and cartenoid
Expand the amount of wavelengths a plant can accept
Action spectrum
A plot of the effectiveness of light of a particular wavelength
How to measure for photosynthesis
Use a suspension of chlorophyll and measure the outgoing oxygen at different wavelengths
Theodor Engelmann
First action spectra. Divided white light with a prism. Placed algae strip with bacteria under different wavelengths of light
Theodor’s results
Bacteria flocked to the red and blue because the most oxygen was present there
Other jobs of pigments
Transfer energy to neighboring molecules. Efficient because they are bound to protein pigments
Pigment proteins
Organized into photosystems
Photosystems
Made of antenna (light harvesting) complex. that surrounds the central reaction center
Central reaction center
A photosystem made of proteins that bind chlorophyll to the primary electron acceptor
Photosystem function
Trap energy to oxidize a reaction of electron transfer to the primary electron acceptor.
2 photosystems
Photo system II and then photo system I
Photosystem I
Chlorophyll A is called p700 (pigment with the max wavelength absorption of 700nm
Photosystem II
P680
In a chloroplast
There are 1000’s of photosystems with 500 chlorophyll molecules each
