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Where does all of our oxygen come from?
How are macromolecules made using sunlight
- Light excites/energizes chlorophyll. That energy
- is used to make ATP and NADPH which are then used to incorporate CO2 into
- 3-carbon sugar
Does photosynthesis involve energy transfer or
- Transformation. Light energy is transformed to
- chemical energy
Although photosynthesis is often described as an endergonic process, why is it actually an exergonic reaction?
- Heat is being dissipated because very little
- light energy is actually absorbed in the process.
What is the electron donor in photosynthesis and what is it oxidized to?
H2O is oxidized to O2
What is the electron acceptor in photosynthesis
and what is it reduced to?
CO2 is reduced to macromolecules such as simple sugars
What is the difference between NADH and NADPH?
Which is used in photosynthesis?
NADPH includes an extra phosphate group. NADPH
What does endosymbiosis tell us about the use of chlorophyll and photosynthesis in eukaryotes?
- Other organisms take in chlorophyll containing
- organisms in order to utilize photosynthesis for themselves
Where do light reactions take place and what is
created (primary and byproduct)?
- In the thylakoids; ATP and NADPH are generates
- as the primary products and O2 is released as a byproduct
Where does synthesis and the Calvin cycle take
place? What is produced?
In the stroma; G3P is generated from CO2
There are three different membranes of the
chloroplast. Where are they located?
- Two membranes around the chloroplast, each
- thylakoid within the chloroplast had a phospholipid bilayer
Where is light harvested and ATP made in the
On the thylakoids membranes
True or false: thylakoids are interconnected in
What happens to the excited electrons on the
They are passed down another electron transport chain and generate NADPH
What is the role of chemiosmosis in
It drives ATP synthesis
Where does the calvin cycle take place? What
does it create and from what?
In the Stroma; It uses ATP and NADPH from light reactions to put CO2 into a 3-carbon sugar
What kind of light energy is used for photosynthesis?
Photons from the sun
Does a shorter or longer wavelength result in
photons with more energy?
What color of light is reflected by plants? What
happens to the other colors?
Green; they are absorbed and used for photosynthesis
Which color of light is used most in
Purple, blue, and red
What are two types of pigments and what do they do?
- Chlorophyll reflects and scatters green light,
- carotenoids reflect and scatter yellow and orange and also transfer light
- energy to chlorophyll and are antioxidants
What is chlorophyll chemically composed from?
What is it similar to?
Porphyrin ring and a hydrocarbon tail, “heme” in hemoglobin and cytochromes
What does a photosystem do? What are the two parts of the photosystem and their function?
- The photosystem harvests light and is located on the membrane of the thylakoid. Energy from excited photons is first absorbed
- into the pigments of the light-harvesting complex. In the reaction center,
- these electrons pass on their energy to chlorophyll electrons.
How many photosystems are part of each
thylakoid? What connects them?
- Two connected by an electron transport chain.
- Photosystem II and then Photosystem I.
Where does Photosystem II get its electrons
from? How does it export them?
H2O; feeds them into electron transport chain
Where does photosystem II get its electrons
from? What happens to them then?
- Electron transport chain from photosystem I.
- They get re-excited from sunlight energy.
How many water molecules are required to obtain 4 electrons? What is left over from the removal process and what do they
- 2; H+ ions and O2 are left over. The H+ ions
- create a high H+ ion concentration within the thylakoid which then drives ATP
- synthesis. The O2 diffuses out of the membrane (passive diffusion because it is
- non-polar and can pass through membrane without any help)
What is the final electron acceptor after
Photosystem I? What does this form and what process does this go to?
NADP+ accepts the electron to become NADPH; it then moves on to the Calvin cycle.
What happens to the H+ ions within the thylakoid space? Where do they go?
- They are actively diffused and used to create
- ATP. The ATP molecule then heads to the Calvin cycle
Where does the Calvin cycle take place? What are the three molecules that go into the Calvin Cycle? What comes out?
In the stroma; CO2, NADPH, and ATP go in; CH2O, NADP+, ADP, and a phosphate group come out
Describe the path of a CO2 molecule as it enters the Calvin cycle.
- The CO2 is added to ribulose biphosphate
- (5-carbons, similar to ribose) to make a 6-carbon molecule using the enzyme
- Rubisco. This 6-carbon molecule then splits into two 3-carbon molecules. ATP
- and NADPH are then used to make G3P.
How many G3P molecules need to be created to have a net gain of one G3P molecule?
What enzyme is responsible for incorporating CO2 into organic molecules?
What is the most abundant protein on Earth?
What is all of a plant’s organic molecules made?
How are the extra molecules stored?
In the Calvin Cycle; as starch
How are the Calvin cycle and Glycolysis similar?
They both make use of G3P