Chapter 7 Flashcards
What is Photosynthesis?
The conversion of light energy to chemical energy in the form of sugar and other organic molecules, a reduction of CO2 and a oxidation of H2O. Opposite of cellular respiration.
What two parts does photosynthesis have?
The light reactions (collect light energy, oxidize H20, store energy as ATP and NADPH) and the Carbon Fixation/Calvin Cycle (uses ATP and NADPH to reduce CO2)
Where do the light reactions happen?
In the thylakoid lumen membrane
What is Chlorophyll?
It’s always bound to proteins and only present in the Thylakoid membrane, it has a hydrophobic tail. It is what captures the light/has pigments.
What is the function of Chlorophyll?
The photon excites the electron and that is what makes photosynthesis happen.
What happens in the Light Reactions?
Electrons are taken away from water to produce oxygen, electrons are excited using light and then they go through a series of reactions to create NADPH
What happens in the Photosystems?
The energy of light is captured by protein complexes called reaction centres, they absorb light and use the energy to excite chlorophyll electrons. The excited electrons are then passed to other carriers.
What does Photosystem 2 do?
Starts things off by oxidizing H2O and taking its electrons, producing O2 and 2H+; supplies 4 electrons to the ETC
What does the Light Harvesting System do?
The light harvesting system helps the reaction centre by absorbing lots and lots of energy.
What does Photosystem 1 do?
Re-excites the electron and then it is used to make NADPH which can be used to convert CO2 into carbohydrates.
What is Photophosphorylation?
Chemiosmosis in the thylakoid lumen.
What is the initial electron donor and final electron acceptor in the light reactions?
Water and NADP+
Where do the “Dark” reactions occur?
In the stoma of the chloroplast
What are the input for the Dark reactions?
The ATP and NADPH produced by the light reactions.
Where does gas exchange occur?
Between the atmosphere and inside the leaf.
What happens during the Carbon Fixation Reactions?
CO2 from the atmosphere is reduced and energized using NADPH and ATP to give simple carbohydrates. Input of CO2, ATP, NADPH and an output of Triose Phosphate.
What is Rubisco?
The most abundant enzyme on earth; accounts for about 40% of leaf soluble protein; fixes CO2 by lining it with the organic products to make sugars.
How many Trios Phosphate make a glucose?
2 G3Ps can synthesize glucose.
What are the three major steps in the Calvin Cycle?
Carboxylation (CO2 taken in), Reduction (putting energy in the first organic product), Regeneration (regenerate the initial starting product)
What are Autotrophs?
Photosynthetic organisms.
What are Photoautotrophs?
Photosynthetic organisms that use light as their energy source and CO2 as their carbon source. Known as Earth’s primary producers and source of organic molecules for heterotrophs.
What is Phototrophy?
Organism that obtains energy from light.
True or False: Photons contain a fixed amount of energy.
True, they must be absorbed for this energy to be used. A photon can only excite an electron when the energy of the photon matches the amount of energy required to raise the electron from the ground state to an excited state.
What are the three possibilities after absorbing a photon?
- The excited electron from the pigment molecule returns to its ground state, releasing the energy through fluoresence
- The energy of the excited electron (but not the electron) is transferred to a neighbouring pigment molecule through inductive resonance
- Excited electron is transferred from the pigment molecule to a nearby electron-accepting molecule called a primary acceptor
