Chapter 10 Parts 1 & 2 Flashcards
What is photosynthesis? ( Broad definition)?
- Take carbon in its oxidized form in the atmosphere ( CO2) and reduce the carbons turning them to sugars.
- This is carried out predominantly by plants and bacteria.
- Very endergonic process.
- The input of energy is from sunlight.
How many stages does photosynthesis occur in?
What are these stages?
- ## 2
- Stage 1: light dependent ( light capturing reactions).
photosynthetic organisms capture sunlight and use it to produces ATP and NADPH.
-Stage 2: Light independent reactions/Calvin cycle. Cells will use the ATP of NADPH that was just made and bring in CO2 from the outside, and use chemical energy from the outside to reduce carbons in CO2.
Where do both stages of photosynthesis take place?
- Chloroplast.
What are the long thin disc within chloroplast?
- Thylakoids
What are the regions of the chloroplast with stacked thylakoids?
Granum.
What is the fluid/liquid matrix of the chloroplast?
- Stroma.
Where do the light dependent reactions occur?
- Thylakoids and their membranes.
Where do the light independent reactions occur?
Stroma
In light dependent reactions what is the biproduct of the formation of ATP and NADPH?
- There is a large production of O2 from the ATP and NADPH.
Photosynthesis utilizes what spectrum of wavelength?
- Visible spectrum of wavelength, basically what humans see as visible.
- 400-710 nm
What dictates the ability to absorb light?
- photosynthetic pigments absorb photons from sunlight.
What are the major categories of photosynthetic pigments?
- Chlorophylls
- a: large hydro-carbon ring structure.
contains a magnesium head region that absorbs light and a tail that anchors to the thylakoid. - b-carotene: much broader and diverse category, smaller and usually has two rings.
What is thin layer chromatography used for?
- isolating pigments via thin layer chromatography
1. ) grind up pigments in a hydrophillic* solvent.
2. ) Spot the crude mixture on the bottom of a filter
3. ) Dip that filter in a reservoir
What is spectrometry?
- You remove the pigments from the chromatography filter and place it in a test tube.
- The test tube has light ran through it and tells the absorption of the pigment..
When do the chlorophylls have peak absorption?
- ) violet-blue light
2. ) orange-red ( weaker absorbance.)
Where to the carotenoids have an average peak absorption?
- blue-early green light.
At what point on the wavelength spectrum is the most amount of oxygen produced?
- Violet-Blue, bottom of the spectrum
What does it mean when we say a photosynthetic pigment has absorbed energy from sunlight?
- When photons strike photosynthetic pigments, they excite electrons within.
- ## This excites the electron to a higher energy state, and the higher the energy the photon the more likely it is for that electron to jump more levels.
Which light is likely to excite an electron to jump more than one level, Blue or Red?
-Blue, lower in nm which equates to more energy.
What is an excited electron?
- An electron that that has absorbed energy from a photon, and has reached an unstable state.
What are the three possible fates for electrons in the excited state?
- ) fall back down to their original energy state and release that energy as heat or fluorescence’s. ( not super productive)
- ————————————————— - ) RESONANCE ENERGY TRANSFER: Because of the arrangements of the photosynthetic pigments in the thylakoid membrane, electrons rise up an energy level and fall back down to their original state. This is then given off to nearby electrons and they become excited->fall->transfer
- ————————————————- - ) REDUCTION/OXIDATION: following the transfer of photon energy transfer, eventually the excited electron will get stripped away and used for some other function.
What are photosystems?
What are their function?
Where are they found?
- clusters of photosynthetic pigments.
- key for RESONANCE ENERGY TRANSFER & REDUCTION/OXIDATION:
- They are found in the thylakoid membrane
What are the antenna complex chlorophyll?
- What is their function?
- chlorophyll that surround the photosynthetic pigments of photosystems.
2. ) they do the initial absorbance of photons from sunlight. - they pass that energy via resonance energy transfer to the reaction center.
What is the name for the specialized chlorophyll in the center of the photosystem?
- What is its function?
- Reaction center
- receives the final excited electron and then has it stripped in the REDUCTION/OXIDATION thing.
Where are the carotenoids found?
- in-between the antenna complex chlorophyll
What are the two different types of photosystems found in chloroplasts?
- Photosystem 1: found in the thylakoid membrane facing the stroma.
Photosystem 2: Found in the thylakoid membrane facing the grana.
Describe the energy transfer in photosystem 2?
- ) Photons are absorbed by the antenna complex chlorophyll and the carotenoids,
- ) then they are passed into the reaction center via resonance energy transfer to the reaction center chlorophyll
- ) The electrons then get excited and bounce up an energy state
- ) those electrons get nabbed by pheophytin,
- ) who delivers those biddies to PQ and then are delivered to the Cyt-c (which functions like the ETC)
In photosystem 1 where is the ATP produced?
- why is that dumb shit important?
- Stroma
- bc this is where the ATP is going to be used later on in the light independent reactions as a source of energy
Describe the energy transfer in photosystem 1?
- ) Photons are absorbed by the antenna complex chlorophyll and the carotenoids,
- ) then they are passed into the reaction center via resonance energy transfer to the reaction center chlorophyll
- ) The electrons then get excited and bounce up an energy state
- ) those electrons get passed to ferredoxin, which then passes those bitch ass excited electrons to an enzyme.
- ) this enzyme ( NADP +) reductase which does a reduction of NADP+ to make NADPH
When does photosynthesis occur at a maximum efficiency?
What is it referred to as?
- when photosystem one and two are working together.
- Electrons can flow from photosystem 2-1, ending up as NADPH.
- Z scheme or noncyclic electron flow
What is the name of the reaction center in the photosystem 2 and 1?
- 2.) P680
- 1.) P700
When is photosystem 2 in its oxidized state?
How does it reduce it self?
- when it gives up the electrons out of the activation center
- it is so electronegative that it that it attracts water molecules and reduces itself and creates oxygen as a biproduct
What is cyclic phosphorylation?
- electrons cycle between photosystem 1 and the cyt-c complex.
- This in turn generates a really strong proton motive force by feeding more electrons through the cyt-c complex and allows for the continuous production of atp via atp synthase via chemiosmosis.
