photosynthesis Flashcards
photosynthesis is:
the process of making energy from sunlight. sunlight, CO2, and water are used to make sugars with high chemical energy and oxygen.
photosynthesis takes place in:
the chloroplasts.
chloroplast numbers:
- usually 40-200 in a photosynthetic cell
- up to 500 000 chloroplasts in one square millimeter in a regular leaf
thylakoids are/contain:
little disks inside chloroplasts. they contain molecules that absorb solar energy in the thylakoid membrane.
when stacked, thylakoids from:
grana.
stroma:
stroma is the fluid-filled interior that surrounds grana.
inside stroma:
there are enzymes that catalyze the conversion of CO2 and water into carbohydrates.
photons are:
packets of energy that absorb light.
wavelengths of visible light are associated with:
photons carrying different amounts of energy.
shorter wavelength photons:
carry large amounts of energy.
longer wavelength photons:
carry small amounts of energy.
all light travels:
AT THE SAME SPEED
a pigment is:
a compound that absorbs certain wavelengths of visible light.
light-dependant reactions are initiated when:
the pigments in the thylakoid membrane absorb light energy.
the main type of photosynthetic pigment is:
chlorophyll. it’s green!
the types of chlorophyll are:
chlorophyll a and chlorophyll b
chlorophyll is green because:
it absorbs blue and red light and reflects green light.
carotenoids are:
a class of pigments that absorb blue and green light and reflect red, orange, and yellow light.
beta-carotene is:
the pigment that makes carrots orange. can also be converted into vitamin A.
a photosystem is:
a core group of chlorophyll molecules and proteins in the center of the cluster.
when a pigment molecule absorbs a photon:
it passes the energy to a unique pair of chlorophyll a molecules associated with the reaction center.
the reaction center is:
a group of proteins.
the antenna complex is:
a collection of proteins and pigments that capture and funnel light. it includes all the surrounding pigment molecules that gather the light energy.
antenna complexes transfer:
light energy to the reaction center.
what happens when the antenna complex transfer the light energy to the reaction center?
an electron in the reaction center becomes excited. said electron then has enough energy to be picked up by an electron accepting molecule, which is reduced. this molecule is then at a higher energy level.
the photosystems found in chloroplasts and algae are called:
photosystem i and photosystem ii
P700 is:
the reaction center pigment molecule in photosystem i
P680 is:
the reaction center pigment molecule in photosystem ii
the photosynthesis electron chain consists of:
protein molecules with prosthetic groups attached.
prosthetic groups:
non-peptide molecules bound to a protein that facilitates its function. ie, coenzymes.
the energy harnessed by both photosystems is used to:
produce ATP and NADPH
photophosphorylation is when:
the electron transport chain in the thylakoid membrane facilitates the movement of H+ ions to create a proton gradient that powers the production of ATP via ATP synthase.
explain the photolysis of water.
water is broken down by light energy to form oxygen moves in the lumen of the thylakoid. hydrogen’s electrons are donated to the oxidized chlorophyll molecules in photosystem ii.
explain the cyclic electron pathway.
this pathway only uses P700 (photosystem 1). it absorbs energy, exciting an electron, which is then passed to ferredoxin (FD). once passed to ferredoxin, it eventually makes its way to b6-fcomplex, where it’s then passed back to P700 to make another cycle. every time the electron is passed to another carrier molecule, it loses energy so that when it goes back to P700, it is at a low energy state and ready to be re-excited. this process only makes ATP; NADPH, which is required to synthesize sugars, is not made.
explain the non-cyclic electron pathway.
both photosystems are utilized in this pathway, creating ATP and NADPH. electrons are replaced via the splitting of water.
an alternate name for the light-independent stage is:
the Calvin Cycle.
the three steps in the Calvin Cycle are:
carbon fixation, reduction of PGA, regeneration of RuBP
light-independent stage takes place after x in x?
takes place after the energy from light-dependent reactions is transferred to the independent stage. takes place in the stoma of the chloroplast.
give a summary of carbon fixation.
a molecule of CO2 enters the stoma through the stomata of the leaf. it combines with RuBP, a five carbon molecule, to make an extremely unstable 6C molecule. this then splits into two 3C molecules called 3PG. this reaction is catalyzed by the rubisco enzyme. this process has to happen three times to proceed to the next stage (needs six molecules of 3PG)
give a summary of fixation.
the 3PG is phosphorylated by ATP, turning it into 1,3-BPG. this molecule is then reduced by NADPH into G3P. some G3P molecules leave the cell to make glucose while others continue onto step 3.
give a summary of regeneration of RuBP.
ATP gives energy so that G3P turns into RuBP. the Calvin Cycle must happen six times to make one molecule of glucose.
numbers in the Calvin Cycle.
of the twelve G3P molecules made in the six cycles of the Calvin Cycle, ten regenerate RuBP and two make glucose.
