Lecture 17 - Photosynthesis Flashcards
Photosyntheis is an ____ process in which sunlight is captured into carbon-containing compound
anabolic
What are the 2 different kinds of photosynthesis?
Oxygenic Photosynthesis (plants)
- water isi oxidized to oxygen
- Co2 gets reduced to carbohydrate
- 6CO2 + 12 H2O + light –> C6H12O6 + 6H2O + 6 O2
Unoxygenic Photosynthesis (other molecules)
- believed to have evolved sooner than oxygenic
What is the electron acceptor in photosynthesis?
NADPH
Photosynthesis consists of two main steps:
- Light Reaction
- light energy is converted into chemical energy of ATP
- production of reduced electron carriers (NADPH) - Light-Independent
- Production of carbohydrate (using ATP, NADPH, and CO2)
- occurs in the stroma
The ____ the wavelength the more energetic.
shorter
When a molecule absorbs photon’s energy it raises from ___ energy state to ___ energy state
low; high
Photosystems
- Large protein systems embedded in thylakoid membrane
- Contain photosynthetic pigments (chlorophyl a, b, and c) and accessory pigments (carotenoids)
- arranged in light-harvesting complexes (antenna system)
- Multiple antenna systems surround a single reaction center
What are the two electron transport processes
- Noncyclic electron transport: utilizes the energy from light to generate ATP and NADPH
- Photosystem 1: contains P700 chlorophylls, passes energized electrons via intermediate molecules to NADP+, reducing it to NADPH
- Photoystem 2: contains P680 chlorophylls, oxidizes water molecules and passes its energized electrons through a series of carriers to produce ATP - Cyclic electron transport: utilizes energy of excited electrons from photosystem 1 and recycles the electrons back to the photosystem 1
- coupled with ETC to chemisomotic production of ATP
Carbon Fixation
- Occurs during the light independent reaction and it uses ATP and NADPH from light reaction to reduce CO2 to sugar (G3P)
- Happens in stroma of chloroplasts
How does rubisco work depending the scenario?
- In higher CO2 concentration, rubisco works as carboxylase and adds CO2 to RuBP (first step of Calvin Cycle)
- In higher O2 concentration, rubisco works as oxygenase and adds O2 to RuBP (which significantly decreases efficiency of photosynthesis)
What is the stromata used for and where is it located?
It is used for gas exchanged and is located underneath the leaves.
(when closed there is a larged stored amt of oxygen)
What happens to a plant when its a hot and dry day?
The stomata closes which leads to limited gas exchange which leads to accumulation of O2 due to the oxidation of H2O which then makes rubisco works as an oxygenase
- carbon fixation is decreased to 75% which means you lose 25% of product result
