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(slide 23) What does the long tail of PQ help it do?
will keep it in the membrane
(slide 23) PQ has a _____ group
< Reduced form
- Oxidized form
- Takes an electron on the top oxygen, where it draws an H
Steps of PSII (3)
1. Excited electron captured by pheophytin
2. Pheophytin then hands it off to PQ
3. Energetic eelctron hen gets handed off to the other members of the electron transport chain
- - R group can be CHO or CH3
- *looks similar to chlorophyll
- - it has 2 H+ in place of the Mg2+
- *no metal in the middle
Where is PS II and the cytochrome located?
Do plants have mitochondria?
What other name is PS II called? and why? (2)
- P is photosystem and 680 is referring to 680 nm light
What do PQs do?
it carries protons to the inside of thylakoids creating a proton motive force
1. absorbs photon of light
2. Chlorphyll hands off electron to Pheophytin
3. Pheo hands energetic electron to PQ
4. AS pQ moves electron around, hydrogen on stroma will go inside thylakoid
5. PQ hands electron to cytochrome complex
- 6. Cytochrome moves more hydrogens in thylakoid
- *building a proton gradient just like cristae
What happens when red light and far red light are combined?
the wavelengths more than doubles the rate of PS
1. The electrons that start this scheme come from the splitting of water
2. it goes through the PS II process
3. After the cytochrome, the electron is handed off to PC (Plastocyanin)
4. PC hands the elctron to PS I
- 5. Far red light radiates P700 (P1) causing the electrons to get excited
- 6. It goes to Ferredoxin, which produces NADPH
WHat links Photosystem I and II?
- *it can carry 1000 electrons per second
1. Far red light excites electrons
2. They will go through the molecule ferrodoxin
- 3. Ultiamtely produce NAPDH
- *reduced version of NADP+
What is PS 1 called? and why?
-for its preference to deep red light
Does the CAlvin cycle use or produce ATP?
-it does not produce ATP, it only uses it
Does the calvin cycle need light>
What happens to the light independent reactions without CO2? (calvin ccyle)
- there is no cycle
WHat was result of Pulse chase exp.?
- - 3 Phosphoglycerate is the first intermediate product to appear.
- *the other ones show up later
What are the 3 pahses of calvin cycle?
- *fixation of carbon dioxide
- * reduction of 3 phosphoglycertae to G3P
- *regenration of RuBP from G3P
(calvin cycle) formula of fixation
3 RuBP + 3 CO2 > 6 3 Phosphoglycerate
(calvin cycle) Reduction formula
6 3 phosphoglycerate + 6 ATP + 6 NADPH > 6 G3P
(calvin cycle) Regeneration
5 G3P + 3 ATP > 3 RuBP
Where do all three phases of calvin cycle take place in?
in stroma of chloroplasts
1. Take RuBP (5 carbons) and attach it to Carbon dioxide (one carbon) to get a six carbon molecule
2. the 6 carbon molecule splits immediately to form 2 3-phosphoglycerate
3. take the 2 3-phosphoglycerate and add ATP and NADPH to ultimately produce 1 G3P
4. Only 1 G3P will be used to produce glucose, the other 5 will go to regenerate RuBP
5. In regenerating RuBP, we oxidize ATP
Where did the ATP and NADPH come from in calvin cycle?
from the light reactions
What does ribulose add?
one carbon dioxide
Is rubisco enzyme fast or slow?
- *only catalyzes about 3 sec
How many active sites does rubisco have where CO2 is fixed?
Is there alot of Rubisco in a plant? if so why?
-yes because it mihgt be that it is slow
Is photoresporation a good thing?
no, it reduces the efficiency of PS using Rubisco
What is it called when CO2 and O2 compete for the enzyme Rubisco?
What is the theory on where Rubisco came from?
an atmosphere with very little oxygen
Rubisco reaction formula with CO2 during PS
RuBP + CO2 > 2 3-phosphoglycerate (used in calvin cycle)
Rubisco reaction with oxygen during photorespiration
RuBP + O2 > 1 3 phosphoglycerate (used in calvin cycle) + 1 2- Phosphoglycerate ( when processed, CO2 released and ATP used)
-stomas can open or close
Why are C3 plants called C3?
bc CO2 first is found as a 3 carbon sugar
Why are C4 plants called C4?
-initially tack on CO2 to a 3-carbon molecule and end up creating an organic acid that has 4 carbons
C3 plants formula
RuBP (5 carbon) + CO2 (one carbon) >(Rubisco) two 3 phosphoglycerate (3 carbon sugar)
C4 plants formula
3 carbon compound + CO2 >(PEP Carboxylase) 4-carbon organic acids
What does PEP carboxylase allow C4 plants to do?
allows it to store amounts of CO2 within the leaf
-have both PEP carboxlase and rubisco but are in separate cell compartments
-increases efficiency in PS
Do C3 plants have PEP carboxylase?
what cells in C4 contain PEP carboxylase?
What cells in C4 contain rubisco?
What happens in C4 plants when carbon dioxide levels are high?
mesophyll cells in C4 plant can make alot of C4 compounds (stored CO2)
What happens if the levels of CO2 are low in C4 plants?
C4 compounds will be released
Similarities between C4 and CAM plants? (2)
-increase efficiency in PS
-they both use PEP and Rubisco
CO2 and C4 plants
CO2 is stored temporarily in another cell in the form of an organic acid
CO2 and CAM plants (2)
-CO2 is taken up when the environment is cool
- -it is stored temporarily aas an organic acid in the same cell
- *single cell has PEP and rubisco
What happens to glucose produced?
either turns into sucrose or starch
In C3 plants, CO2 is...
attached to RuBP which then quickly splits into 2 molecules of 3-phosphoglycerate
Where does most of the mass come from as the tree grows?
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