Unit 3- Ch 8
Excitation of electrons in which photosystem results in the production of ATP?
Photosystem II & Photosystem I II- linear e- flow I- cyclic e- flow
Where are photosystems II and I of the photosynthetic electron transport chain located?
Photosystems II and I are located in the thylakoid membrane
During photosynthesis, where will protons accumulate?
Protons accumulate in the lumen during illumination as a result of 1) splitting of water, and 2) via the pumping of protons from the stroma by the cytochrome complex.
RuBP stands for ...
RibUlose 1,5-BisPhosphate
Which compound is required for the carboxylation step of the Calvin cycle?
RuBP
The regeneration of RuBP typically limits the rate of photosynthesis under low light intensities. This is because:
RuBP regeneration requires ATP
The chlorophyll in photosystem II is said to be a very powerful oxidizing agent. This is best shown by its ability to:
Take electrons away from oxygen in water, releasing oxygen gas
What process provides an eventual carbon source for glycolysis?
The Calvin cycle produces 3-carbon compounds, which are ultimately converted into 6-carbon carbohydrates in the cytoplasm. These 6-carbon carbohydrates can then be used in glycolysis.
In which cellular location does the majority of photosynthetic electron transfer take place?
The majority of photosynthetic electron transfer is carried out by protein complexes photosystems II and I, which are located in the thylakoid membrane.
A researcher is carrying out an experiment where she labels a protein with a fluorescent tag (so she can visualize its location in a cell) and introduces this tagged protein into the lumen of a single thylakoid. She observes her treated cells periodically and notices that the labeled protein can move between grana and is always in the lumen, but is never observed in the stroma. What can she deduce?
The protein likely travels through a common lumen shared by thylakoid membranes and grana, adn cannot easily diffuse through the thylakoid membrane.
Suppose a plant is exposed to a toxin that causes the thylakoid membranes to become much more permeable to protons than normal. Which of the following would be true?
The reduction and regeneration steps of the Calvin cycle would slow down and eventually stop.
Which of the following is true when comparing the Calvin cycle and light-harvesting reactions of photosynthesis?
They take place in different compartments of the same organelle.
Rubisco can function as either a carboxylase or an oxygenase. [T/F]
True
The products of the Calvin cycle are 3-carbon sugars. [T/F]
True
Which molecule is initially oxidized to provide electrons for the photosynthetic electron transport chain?
Water. In photosynthesis, water is oxidized and releases oxygen, whereas carbon dioxide is reduced and forms carbohydrates.
Why is rubisco the most important enzyme on earth?
attaches CO2 to 5 carbon RuBP to produce two 3 carbon molecules: where carbons for All organic molecules come from
Starting with an acorn. A log from an oak tree may weigh 10,000 times as much as the acorn. Where has MOST of the mass of a dead log come from?
carbon from CO2 in AIR
3 phases of the calvin cycle:
carboxylation, reduction, regeneration
How does the metabolism occurring in chloroplasts differ from that of mitochondria?
different electron acceptors and electron sources
Cyclic electron transport enhances ATP production because:
excited electrons are transferred from PS I back to plastoquinone
18^O is a radioactive isotope of oxygen. Which experiment will produce 18^O2? 1: radioactive water + CO2 2: water + radioactive CO2
experiment 1
From where does the oxygen come that is produced as a by-product of photosynthesis?
from the breakdown of water
Sequence of the flow of energy in a living system:
light → photosynthesis → carbohydrate → cellular respiration →ATP → heat - Essentially, all of the energy in biomass ultimately arises from sunlight via photosynthesis and results in carbohydrate. This captured energy is finally dissipated as heat from the processes and products of cellular respiration.
NADPH production in photosynthesis requires:
light, electrons, and protons
If no light is available, how can a plant make ATP?
mitochondria break apart stored glucose and produce ATP
In the Calvin cycle, NADPH is:
oxidized
The photosynthetic reaction center becomes ________ when it passes its __________ to the ______________, which is thus ___________.
oxidized; excited electron; electron acceptor; reduced
Accessory pigments: definition
pigments other than chlorophyll in photosystems - notably carotenoids
Which of the following is part of the photosynthetic electron transport chain between photosystems I and II?
plastocyanin, cytochrome-b6f complex, plastoquinone
Which step of the Calvin cycle would be affected first by a lack of NADPH?
reduction
Rubisco is short for ...
ribulose biphosphate carboxylase oxygenase
carbohydrate synthesis takes place in:
stroma
Where does the Calvin cycle take place?
stroma of the chloroplast
photc zone: definition
surface layer of ocean [to ~100m down] where photosynthesis can occur
the photosynthetic electron transport chain is sometimes referred to as ____
the Z scheme
When 3 molecules of CO2 react with 3 molecules of RuBP in the calvin cycle, 6 G3P are produced. 1 G3P exits the calvin cycle. What happens to the other 5?
they are converted back into RuBP to continue the calvin cycle
Chloroplast ATP synthases are powered by the flow of protons from the:
thylakoid lumen to the stroma
In the chloroplasts of plant cells, the absorption of light energy and the movement of electrons along an electron transport chain occur in the _____, and the synthesis of carbohydrates takes place in the _____.
thylakoids; stroma
energy transfer steps result in the formation of 3-carbon carbohydrate molecules known as _______
triose phosphates
Calvin Cycle Uses: [3]
- CO2 - ATP - NADPH
Photosystem II Uses: [2]
- H2O - ADP+Pi
Photosystem I Uses: [1]
- NADP+
Photosystem I Produces: [1]
- NADPH
Photosystem II Produces: [2]
- O2 - ATP
Calvin Cycle Produces: [3]
- glucose - ADP+Pi - NADP+
Which traits do photosynthesis and oxidative phosphorylation have in common?
-redox reactions and the electron transport chain generate potential energy to synthesize ATP. - a proton electrochemical gradient provides the potential energy to drive the ATP synthase, which converts potential energy into kinetic , and then into chemical energy (ATP). - take place in organelles that have double membranes.
For every six CO2 molecules incorporated into carbohydrate molecules, how many triose phosphates (G3P) can be exported from the chloroplast?
2: Triose phosphate is a 3 carbon sugar, so 6 CO2 molecules would yield 2 triose phosphate molecules
How many CO2 molecules must enter the Calvin cycle for each molecule of triose phosphate (G3P) exported from the chloroplast?
3
The product of the Calvin cycle is a triose-phosphate sugar that is either exported from the chloroplast or used to regenerate RUBP. How many times must each of the reactions in the Calvin cycle take place in order to complete the synthesis of one 3-carbon triose phosphate sugar molecule?
3
product of carboxylation
3-phosphoglycerate (3-PGA)
At the end of linear e- flow, where is the light energy that was absorbed and converted by chlorophyll stored?
ATP & NADPH
In photosynthesis, the reduction of 3-phosphoglycerate to form carbohydrate requires:
ATP & NADPH
If plants are exposed to a toxin that makes the thylakoid membrane leaky to hydrogen ions, the rate of ATP production in the chloroplasts will most likely ____
ATP production will decrease
Electrons removed from H2O molecules are transported through the photosystems and photosynthetic electron transport chain and are ultimately used to reduce NADP+ to NADPH. At what point fot he e- have the greatest amount of potential energy?
After capturing photon energy in the reaction center of photosystem II
Which of these is responsible for the transport of electrons between photosystem II and photosystem I?
Cytochrome b6f
In animal cells, most ATP synthesis takes place in mitochondria, but in plant cells, most of the ATP used is made in the chloroplasts. [T/F]
False
In an experiment, a radioactively labeled CO2 is added to a growing plant cell, and radioactive acetyl-CoA is produced and collected. In what order does the molecule of CO2 pass through the indicated cellular locations as it is converted into acetyl-CoA?
For the radioactive CO2 to be incorporated into acetyl-CoA, it must never leave the cell. CO2 is captured (fixed) by the plant cell in the Calvin cycle, which takes place in (chloroplast - stroma). From there, CO2 is incorporated into a 3-carbon compound, which is exported into the cytoplasm and converted into a 6-carbon carbohydrate. This 6-carbon carbohydrate then undergoes glycolysis (cytoplasm) to produce two molecules of radioactive pyruvate. If radioactive acetyl-CoA is collected, this happens via oxidation of the radioactive pyruvate in (mitochondrion - matrix).
At the end of the calvin cycle, what molecules have the energy that originally came from light?
G3P
Photosystem II and photosystem I differ in:
H+ production and electron donors & acceptors
In plants and algae, ____ is the source of the electrons needed for photosynthesis.
H2O
When chlorophyll in solution returns to its ground state via energy release, it is ready to absorb another photon. How is this different in the reaction center chlorophyll in the chloroplast?
In the chloroplast the reaction center chlorophyll must obtain a replacement electron.
How is the energy in a photon of light stored in a molecule of the sugar G3P?
Light energy energizes electrons to make ATP and NADPH, which provide energy to produce G3P in the Calvin Cycle
In which cellular location does the majority of mitochondrial electron transfer take place?
Mitochondrial electron transfer is carried out by the protein complexes that make up the electron transport chain, which are located in the mitochondrial inner membrane.
NADPH stand for ...
Nicotinamide Adenine Dinucleotide Phosphate
Which two molecules are produced by the photosynthetic electron transport chain and used in the Calvin cycle?
Only ATP and NADPH are produced by the photosynthetic electron transport chain and used in the Calvin cycle.
