The Processes of Photosynthesis Flashcards
Photosystems
clusters of chlorophyll and proteins in thylakoids
Why are photosystems essential to photosynthesis
bc they are surrounded by accessory pigments
Photosystems are a part of
photosynthesis
what is the function of photosystems
to absorb sunlight and generate high energy electrons which are passed to electron carriers in the thylakoid membrane
Do all plants have the same photosystems
no
How many photosystems are there
2
what are the names of the photosystems
photosystem 1 and photosystem 2 (but in roman numerals )
Which photosystem comes first in photosynthesis
photosystem 2
What is the function of photosystem 2
to absorb light to kickstart the light-dependent reactions (aka photosynthesis)
Where is light absorbed in photosystem 2
electrons in the pigments
What is the symbol for high energy electrons
e-
What happens to the electrons after they absorb the light energy
they are passed down to the electron transport chain
is an electron transport chain included in photosystem 1
yeessss
where is the electron transport chain found
thylakoid membrane
what is the electron transport chain
a series of electron carrier proteins that move high energy electrons during ATP generated reactions
Is the electron transport chain in cellular respiration and photosynthesis the same?
no
What is the last step of photosystem 2
enzymes on the inner surface of the thylakoid membrane break up water into 2 electrons, 2 H+ and 1 oxygen
Since the high energy electrons are always transferred to the electron transport chain does chlorophyll ever run out of electrons?
no the electrons that are transferred to the electron transport chain are replaced by electrons that are released when enzymes break down water
What signalizes the end of photosystem 2
water is broken down by enzymes
Is there a step between photosystem 2 and photosystem 1?
yesh - intermediate step - electron transport chain
what happens in the intermediate step of photosynthesis?
energy in electrons is used to pump H+ ions through proteins from the stroma into the thylakoid space
What are the products/byproducts of photosystem 1?
1 oxygen - byproduct and 2 electrons and 2 H+ -> products
at the end of the electron transport chain…
electrons transfer to photosystem 1
Do electrons have the same energy when they reach photosystem 1?
no bc some energy has been used to pump H+ ions across the thylakoid membrane
How does photosystem 1 compensate for the loss of energy in the electrons
pigments in photosystem 1 use energy from light to reenergize electrons
How many electron transport chains are in photosynthesis?
2
What happens in the second electron transport chain
NADP+ molecules in the stroma pick up the high energy electrons and H+ ions on the outer surface of the thylakoid membrane to become NADPH
What is the charge of the stroma
negative
why is the stroma negatively charged
bc of the accumulation of hydrogen ions that were pumped into it
gradient
an area over which something changes
Can H+ ions cross the membrane directly
no bc they are ions
How do H+ ions pass through the membrane
through the ATP synthase
what is the ATP synthase powered by
gradient
What provides the energy to make ATP
the difference in both charge and H+ ion concentration across the membrane
As H+ ions travel through the ATP synthase it
rotates
What happens as the ATP synthase rotates
it binds a phosphate group to ADP to produce ATP
chemiosmosis
the process in which a phospate group is added to ADP to create ATP
What are the final products of photosynthesis
ATP and NADPH
the light independent reactions are aka
calvin cycle
What are the reactants of the calvin cycle
NADPH ATP and O2
What factors influence the rate of photosynthesis
temperature, light intensity, and the availability of water
Where does the carbon dioxide enter from
atmosphere
What happens to the carbon dioxide once it enters the calvin cycle
an enzyme in the stroma binds it to 6 5-carbon compounds that are already present in the organelle
How many carbon dioxide molecules enter the organelle
6
what is created when 6CO2 binds with 6 5-carbon compounds
twelve 3-carbon compounds
As the 3-carbon compounds move through the cycle what occurs
they gain energy from ATP and NADPH in the stroma
At midcycle two of the twelve 3-carbon molecules are ____ from the cycle
removed
what happens to the two 3-carbon molecules that leave the cycle
they become the building blocks that the plant cell uses to profuce sugars, lipids, amino acids, and other compounds
What happens to the remaining 10 3-carbon molecules
they are converted back into six 5-carbon molecules which combine with six new carbon dioxide molecules to begin the next cycle.
What are the products of the calvin cycle
C6H12O6 and other carbohydrates (3-carbon molecules that leave), 3 ADP and 2 NADP+ (transfer of energy in calvin cycle)and also removes CO2 from the atmosphere
