Chapter 10 Parts 3 & 4 Flashcards
What do the stoma control?
They can open and close to allow for the diffusion of gas into and out of the cell.
How is carbon involved in the Calvin cycle.
CO2 enters the cell via the stoma and then is reduced to make sugars.
Where is the Calvin cycle taking place?
- The stroma of the chloroplast.
- the liquid matrix of the chloroplast
What are the phases of the Calvin cycle?
- ) Fixation
- ) Reduction
- ) Regeneration
Describe the fixation phase of the Calvin cycle?
- grab gases from the atmosphere ( CO2) and stick them to organic molecules within the cell.
- .) 3RuBP + 3CO2 —–> 6 3PGA
Where does the energy from the reduction phase of the Calvin Cycle come from?
- Products of the light dependent reactions, these occur prior to the Calvin Cycle.
- Chemical energy in the form ATP and NADPH
Describe the reduction phase of the Calvin Cycle?
- The product from fixation: ( 2 3PGA) is put into a reaction with the products from the light dependent reactions (ATP & NADPH).
- To form two organic molecules ( 5G3P & 1 G3P)
- 2 3PGA + 6ATP & 6NADPH —-> 5G3P & 1 G3P
What did Dr.Reedy say the ATP and NADPH were created for via the light dependent reactions?
- Motha
- Fuckin
- CARBON REDUCTION
t/f : all steps of the Calvin Cycle occur in the same place?
True, they all occur in the stroma.
What takes place in the regeneration phase of the Calvin Cycle?
- Some products of the previous steps are used to regenerate RuBP.
- 5G3P + 3ATP —-> 3RuBP
What do the 3CO2 that we begin the Calvin Cycle with tell us?
- Since the product is G3P, which is a carbon compound, we known that serves to build other organic molecules.
- Therefore, if you bring 3 carbons into the system you are able to pull out three to get back to where you started.
T/F: Rubisco is the most abundant enzyme on the planet?
True
What does Rubisco do?
- It is a massive enzyme used to catalyze the fixation phase of the Calvin Cycle.
- Grabs a CO2 and binds it to the end of a 5 carbon compound RuBP.
In the fixation phase of the Calvin Cycle what happens after the RuBP has a CO2 bound to its end?
- Forms a 6 carbon complex that is cut in half to form 2
3PGA.
How many active sites does the enzyme, Rubisco, contain?
- What does this mean in terms of its effectiveness?
- 8
- 2.) It can potentially catalyze 8 of these reactions at one time, thus “ making it an absolute fucking Pablo Escobar”- Marcus Reedy PhD.
What provides the energy in the first step of the Reduction phase?
i.e. the 3PGA needs what to move to the second step?
- 6 ATP
What provides the energy in the second step of the Reduction phase allowing for the reduction of carbon to form G3P?
Energy from 6NADPH
Out of the 6 G3P that are produced from the reduction phase, how many are pulled out to make other organic molecules?
- What are examples of those other molecules that are being made from G3P + only Jesus knowns?
- ) 1 is removed.
2. ) Fructose, glucose, etc.
Where do the 5 remaining G3P go?
- They enter the regeneration phase of the Calvin Cycle.
- This plus in addition to ATP is used to regenerate RuBP.
What is the purpose of the regeneration step to the Calvin Cycle?
- Regenerate RuBP so the cycle may continue.
How many times does the Calvin Cycle have to occur?
- Why
- ) 3 cycles per influx of 3 CO2
- ) this is because we only remove one G3P per cycle and we need to remove 3 G3P to create a full one.
- A full one allows for the creation of other organic molecules.
What was Marcus’s PR Bench Press?
- With a greater concentration of mitochondria located in his pec’s and tri’s what did this equate to?
- A shear minimum of 675 pounds
- Thor’s strength and an absurd amount of dates from women in the biology department
What do the sugars made from the Calvin cycle do?
- They are used to make sucrose or starches
What is the chemical equation if Rubisco is in the presence of lots of O2 molecules?
i.e. what reaction is taking place in the fixation step of the Calvin Cycle?
RuBP + O2 —-> 3-phosphoglycerate( used in Calvin Cycle) + 2-phosphoglycolate (when processed CO2 is released and ATP is used)
When does oxygen bind to the Rubisco?
During photorespiration
What is the problem with the 2-phospohglycolate produced when O2 + RuBP occurs?
- it requires a fair amount of energy ( ATP) to break it down, and it isn’t very useful in the cell.
- Further it hinders the effectiveness of the photosynthetic ability of the plant.
If their is a massive influx of oxygen what will likely be carried out?
- Photorespiration:
Why is photorespiration a problem for plants that live in prolonged extremely dry conditions?
- Yes, when their stomata open CO2 can diffuse in and O2/H2O out, but plants also loose water vaper.
- Water vapor loss is significant: since it is a prolonged period of dryness the plant can begin to desiccate.
How do plants in extremely dry conditions keep from desiccating?
- What does their counteraction do?
- They close their stomata for long periods of time.
2. ) because the stomata are closed no more CO2 can diffuse in and O2/H2O can’t get out - This leads to photorespiration.
What is the alternative pathway that plants in prolonged dry conditions use instead of photorespiration?
The C4 pathway:
- There is use of an alternate enzyme PEP carboxylase.
- This takes CO2 from the atmosphere and places it on a 3-Carbon compound generating a four carbon acid.
What is the chemical equation of the C4 pathway in plants?
- C4 plants:
3-Carbon + CO2 ——————————-> 4-carbon organic
compound PEP carboxylase acid
What is the chemical equation of the C3 pathway in plants?
- C3 plants:
RuBP + CO2 ————————–>2 3-phosphoglycerate
Rubisco ( 3-carbon organic acid)
What are the two broad categories of plants that use the C-4 pathway of carbon fixation?
- Also, describe the differences between the two.
C4 plants: mesophyll cells that contain PEP Carboxylase carry out these reactions.
- The product, a four carbon compound is eventually broken down, and the CO2 is re-released to diffuse into the adjacent bundle sheath cells.
- These cells carry out normal photosynthesis, as light independent reactions occur here and meaning there is no excess of O2.
——————————————————————–
CAM plants: They open up their stomata at night using PEP Carboxylase, when it is safe ( sun involves water vapor loss).
- At night they open the Stomata and CO2 enters the cell.
- PEP Carboxylase fixes the CO2 and generates a 4-C compound.
- It does through the duration of the night and builds up large quantities of the 4-C compound.
- Then, during the day the 4-C compound is broken down to CO2 and the Calvin cycle can occur.
——————————————————————-
Commonalties: Both contain rubisco, but carry out C4 pathway first.
Which cells near the leaf surface contain the PEP carboxylase?
In these cells what other type of reaction occurs here?
- The mesophyll cells.
- The light dependent reactions.
Which cell near the leaf surface contains rubisco?
In these cells what other type of reaction occurs here?
bundle sheath cells.
They carry out light independent reactions, therefore they lack oxygen and they can continue to carry out photosynthesis.
CAM plants vs C4 plants?
examples?
CAM = desert shit C4 = shit in Omaha- Dr. Sneedy
