Photosynthesis Flashdeck for USABO

What pigment makes up 75% of the pigments that are present in the plant’s leave’s for photosynthesis?

Chlorophyll A

What are the pigments that are present in the plant’s leaf for photosynthesis, and what are their functions during photosynthesis?

Chlorophyll A, B, D, and F. Chlorophyll A is the main one in the leaves that is responsible for light harvesting while B is present in plant’s and algae and euglenoids. D and F specialize in absorbing lights with the longer wavelengths

Catenoids

Red, Orange, and Yellow pigments that are responsible for providing photoprotection for the plant’s cells.

What are the three different things that can occur when light hits the leaves of a plant, and what happens when it makes each one of these processes occur?

Fluorescence, which is basically when the chlorophyll reflects the sunlight, this is useless for photosynthesis. Another method is resonance, which is when the light energy is transferred to the neighboring pigments, which ultimately reaches the reaction-center complex. The other way is that it can be sent to an ETC, which leaves holes in the pigments of the plant’s leaves.

What exactly are photosytsems and what do they consist of?

They are hundreds of pigments that are arranged together to take advantage of resonance energy transfer. They contain antenna complexes, which are pigments that are responsible for getting/absorbing light and sending them to the reaction center complex in the center via resonance energy transfer. They can also have light harvesting complexes, which do not have a reaction center complex in the center.

What are light reactions, and what are the two forms that they come in? What do they each produce, and what is the ratio of NADPH to ATP that is required by the Calvin Cycle?

They are the reactions that are responsible for harvesting light from sunlight and they convert it into ATP and NADPH. They come in linear electron flow (ATP, NADPH) along with cyclic electron flow(Only ATP). Calvin Cycle needs a 3:2 ratio of ATP to NADPH.

What is linear electron flow, and is the ultimate goal of it?

The ultimate goal for linear electron flow is to reduce NADP+ to NADPH. It does this by electrons that are passed from Photosystem 2 to photosystem 1 via an ETC, and from there another ETC transfers it to the NADP+, making it into NADPH.

What wavelengths of light is photosystem 2 and photosystem 1 best at capturing?

Photosystem 2 is the best at capturing lights of wavelengths 680 while photosystem1 is the best at capturing wavelengths of 700.

What is responsible for splitting water in the photosystems and why is this important for both of the photosystems during photosynthesis? What photosystem does it occur in?

The molecule that is responsible for splitting water is Manganese and it occurs during Phototsystem 2 as a method of replenishing the electrons that are donated by P680

Which are the first two molecules in the ETC that end up dealing with the electrons that are released by the photosystem 2 and such?

The first two cytochromes in the ETC for photosythesis are pheocytin and plastiquinone. They are responsble for shuttling electrons across from photosystem 2 for powering the calvin cycle and eventually to photosystem 1.

What are the two binding sites within Plastiquinone and what is each responsible for?

The two binding sites within the first two cytochromes of the plant ETC are QA and QB. QA relays the electron that is recieved by pheocytin and passes it onto plastiquinone. From there, QB, can turn into plastiquinol after recieving two electrons and two protons from two excitations of from two photons, and from te water splitting, it also recieves two H+ protons, allowing it to go to the Cytochrome b6f complex.

What does the B6F cytochrome Complex do in order to ensure that ATP is generated via the chemiosmois?

It pumps protons into the thylakoid lumen while also passing down electrons. By doing so, the ATP synthase is activated as it pushes the protons from the thylakoid lumen into the stroma. It does this by going into the rotor, which spins the internal rod, which causes the catalytic knob to spin, which then causes the ADP and Phosphate to bind, generating ATP for the cell.

Which way does the protons move in comparison with cellular respiration?

In cellular respiration, protons want to move outside the cell. They move from the intermembrane space to the matrix while protons move from the lumen to the intermembrane space.

What is the ETC Chain in order for the transition from Photosytem 2 to Photosystem 2? Also what is the final step catalyzed by?

The chain is in this order as follows: Phylloquinone, Iron-Sulfur Proteins, Ferredoxin, and Flavoproteins, which eventually ends up becoming NADPH at the end. It is catalyzed by an enzyme knows FNR, which turns it into NADPH.

How many water molecules are required for the Photosystem process of linear electron flow to occur and how many NADPH are generated as a result?

6 Water molecules are required as a source of input, and it makes 12 NADPH molecules towards the end as each water molecule contributes 2 electrons as well.

Which photosystem does cyclic electron flow utilize?

It only utilizes the photosystem 1 and it does not utilize photosystem 2.

How does Cyclic Electron Flow work, and make sure to go into it in detail.

Cyclic electron flow works by only utilizing photosystem 1. This happens when the photons excite the electrons in chlorophyll A. This causes it to go to P700 via resonance energy transfer. From there, it goes up as it is being excited and it goes through phylloquinone, and from there it travels to iron-sulfur proteins. After, it goes iron-sulfur proteins into the Ferredoxin, and then from there it goes into cytochrome b6/f complex, where it undergoes chemiosmosis for ATP production. No NADPH is produced at all.

What is the Calvin Cycle responsible for producing ultimately, and where does the production of the glucose sugar happen eventually within the chloroplasts?

Calvin Cycle is responsible for the production of glucose by taking in Carbon Dioxide using the stomata along with the products of ATP and NADPH from the light reactions. It accomplishes this task via a process known as Carbon Fixation

What is photophosphorylation?

It is a process where chemiosmosis is involved to produce ATP in the light reaction stage.

Describe the steps of the Calvin Cycle including all of the chemistry that is involved.

During the Calvin Cycle, the first step in when a CO2 molecule binds with the 5 Carbon Ribose - Biphosphate molecule. This is faciliated by RuBISCO. This 6 carbon molecule splits into 2 3-carbon molecules. From there, the 3 Phosphate Glycerate is converted to to a 3-Biphopshoglycerate via the 3 Phosphoglycerate kinase enzyme. From there, with the help of Glycerayde 3 Phosphate dehydrogenase, they are turned in PGAL. From there 2 G3P molecules are produced, glucose, by using 6 CO2 molecules. This required an input of 18ATP and 12 NADPH from the light reactions in order for this to have happened.

What exactly is photorespiration and what problem does the plant cell try to solve by using this process?

Photorespiration is a process when the plant cell tries its best to make the most out of a bad situation when the RuBisCO enzyme chooses to catalyze oxygen related reactions instead of Carbon dioxide due to it high oxygen affinity. It involves many of the cell organelles while also wasting lots of ATP in the process, which does not make it ideal for the plant cell.

What is spatial separation and how is it used in the plant cells?

Spatial separation is when the plant cell tries to separate the RuBisco from the Oxygen high related areas within the plant cells. The plant cell does not want the RuBisCO to get involved with the oxygen as it is disastrous for the cell.

What molecule does RuBisCO form when it is near oxygen and from it’s oxygen high affinity?

It forms a molecule known as phosphoglycolate

How does the Kranz Anatomy and how does the Hatch-Slack pathway work as well?

It works by making the mesophyll places where the carbon is fixed, and then they use RuBisCO in the bundle-sheath cells that are located underneath the mesophyll cells. A CO2 molecule is attached to a PEP molecule, which forms a four carbon structure known as oxaloacetate. This happens via the PEP Carboxylase enzyme. Later, Oxaloacetate is transformed into either malate or asparate, which are then transported to the bundle sheath cells, and they are broken down into CO2 and pyruvate. It goes back into Calvin Cycle to regenerate the PEP molecules.

What are CAM Plants?

CAM Plants are plants that deal with photorespiration by separating the calvin cycle and the carbon fixation phase. They happen at different times. They open stomata in the night and perform same process and Kranz anatomy as C4 plants