8.3 The Process of Photsynthesis Flashcards
(27 cards)
The light dep. use energy from sunlight to produce oxygen and convert ADP and NADP+ into:
the energy carriers ATP and NADPH
photosystems are:
clusters of chorophyhll and proteins in thylakoids
what do photsystems do?
absorb sunlight and generate highenergy electrons that are then passed to a series of electron carriers embedded in the thylakoid membrane
light energy is absorbed by electrons in the pigments found within:
photosystem 2, increasing the electron’s energy level, then these high energy electron (e-) are passed to the electron transport chain
the electron transport chain is:
a series of electron carrier proteins that shuttle high energy electrons during ATP generating reactions
The thylakoid membrane’s system that provides new electrons to replace the ones it has lost uses a process called:
photolysis: the process of useing light to break up water molecules
Replacement electrons comes from water molecules, which enzymes on the inner surface of the thylakoid break up each:
water molecule into 2 electrons , 2 H+ ions, and 1 oxygen atom. The 2 electrons replace the high energy electrons that have been lost to the electron transport chain
After photolysis what happens to the oxygen and hydrogen ions?
oxygen is released into the air, and the hydrogen ion left behind when water is broken apart are released inside the thylakoid
As electrons move down the electron transport chain energy from the electrons is used:
by the proteins in the chain to pump H+ ions from the stroma into the thylakoid space
At the end of the electron transport chain, the electrons pass through:
a second photosystem, photosystem 1
pigments in photosystem 1 use the light energy to:
reenergize electrons
At the end of a short, second electron transport chain:
NADP+ in the stroma pick up the high energy electrons, along with H+ ions at the outer surface of the thylakoid membrane, to become NADPH
The buildup of H+ ions makes the stroma negativley charged relative to the space within the
thylakoids- this gradient provides the energy to make ATP
ATP synthase is a:
protein in the thylakoid memebrane that allows H+ ions to pass through it
Powered by the gradient, H+ ions pass through ATP synthase and force it to:
rotate (like a turbine being spun by water)
As the ATP synthase rotates, it binds:
ADP and a phosphate together to produce ATP, the process is chemiosmosis
What is the calvin cycle also called?
the light independent reactions
In the Calvin cycle, plants use the energy that ATP and NADPH contain to build:
stable, high energy carbohydrate compounds that can be stored for a long time
During the light ind. reactions, ATP and NADPH from the light dep. reactions are used to produce:
high energy sugars
Describe the 1st step of the Calvin Cycle:
6 CO2 molecules enter from the atmosphere and an enzyme in the stroma combines the CO2 with six 5-carbon compounds already present in the organelle, producing twelve 3-carbon compounds which continue the cycle
in the calvin cycle, for every 6 CO2 molecules,
12 3-carbon compounds are produced
Describe the 2nd step of the calvin cycle:
Other enzymes in the chloroplast convert the 3 carbon compounds into higher energy forms, the energy for these conversions comes from ATP and the high energy electrons from NADPH
describe the 3rd step of the Calvin Cycle:
2 of the 12 3-carbon molecules are removed from the cycle-—these molecules are used to produce compounds like sugars, lipids, amino acids
Describe the 4th step of the Calvin Cycle:
the remaining 10 3-carbon molecules are converted back into 6 5-carbon molecules and combine with six new CO2 molecules to begin the cycle again
