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chapter 10 concept map-photosynthesis (photosynthesis- (photosynthesis…
chapter 10 concept map-photosynthesis
photosynthesis-
cellular organelles called chloroplast capture light energy and convert it to chemical energy that stored in sugar and other organic molecules
the chimcal reaction of photosynthesis is as follows-
6 CO2 + 12 H2O + Light energy S C6H12O6 + 6 O2 + 6 H2O
autographs sustain themselves w/o eating other living things, requiring only water,minerals, and sunlight
adversely, heterotrophs obtain food by consuming other organisms.
leavs are major sites of photosynthesis, and are generally found in the cells of the mesophyll, tissue in the inerior of the elaf.
carbon enters lead, and oxygen exits via microscopic pores called stomata
a chloroplast has two membranes surounding a fluid called the stroma.
suspended within the stroma is a third membrane system, made of sacs called thylakoids
chlorophyll, which gives plants its green pigment, resides in the thykaloid membranes of the chloroplast.
photosynthesis consist of two processes. one known as the light reactiops and calvin cycle phases
NADP stores electrons made from the splitting of water. the chlorophyll light reactions reduce NADP to NADPH by adding a pair of electrons .
the light reactions also generate AT, then use chemiosmosis to power an additional phosphate , a process caleld photophosphorylation
calvin cycle- begins by incorporating CO2 from the air into organic molecules present in the chloroplast. this is known as carbon fixation
makes sugar, but can only do so with the help of NADPH and ATP from light reactions.
light reactions convert solar energy
chloroplast are powered by the sun, their thylakoids convert light energy into that of ATP and NADH, synthesizing glucose and other energy sources
distance between crests of electromagnetic energy is called wavelength.
entire range of radiation is the electromagnetic spectrum
most important to life is the band from 380 nm - 750nm in wavelength, also called visible light, as detected by human eyes
light contains particles known as photons, and the amount of energy relates to the wavelength, the shorter wavelength the more energy in each photon of that light
pigments absorb light of different wavelengths.we see green on leafs because absorbes violet blue light and red light while reflecting green light
the ability to measure the wavelengths a pigment can absorb is done by using a spectrometer
a graph use to plot a pigments light absorption versus wavelength is an absorption spectrum.
plants capture solar energy
chlorophyl a- light capturing pigment in chloroplast, and chlorophyll b- , and accessory pigments called cartenoids, are three different pigments capturing lights in plants.
violet blue light and red light work best for photosynthesis
confirmed by action spectrum, profiling effectiveness of different wavelengths
when chlorophyll absorb light
when molecule absorbs a photon of light, the molecules electrons are elevated to an orbital where it has more potential energy.
a photo system- composed of a reaction center complex surrounded by several light-harvesting complexes.
each light harvesting complex- consists of various pigment molecules bound to proteins.
primary electron acceptor-molecules capable of accepting electrons and becoming reduced.
allows to not only boost their own energy state, but transfer electrons to a different molecule
thykaloid is poweered by two photosystems that corporate light inr eactions of photosynthesis- photosystem 2 -PS2-known as P680 for best absorbing light wavelength. and photosystem 1 -PS1 also called P700, best for absorbing light at 700nm
linear electron flow- flow of electrons in the photosystems.
photon of light strikes pigment molecules in PS2 complex, boosting one of its electrons to a higher state. as electron falls to ground state, electron of a nearby pigment is also raised to higher state. this process continues untilit reached PS2.excites an electron in this pair of chlorophyls to higher energy state.
electron is transfered from the excited P680 state to the primary acceptor. the resulting form of P680 missing the negative charge electron is P680+
an enzymne catalyzes the splitting of a water molecule into two electrons,two hydrogen ions H+ and an oxtgen atom.eectrons are supplied one by one to the p680+ pair, each electron replacing one transferred to the primary electron acceptor. H+ are released into the thylakoid space. oxygen atom combines with oxygen atoms generated by the splitting of anothermolecule forming 02
Each photoexcited electron passes from the primary electron acceptor of PS II to PS I via an electron transport chain, the components of which are similar to those of the electron transport chain that functions in cellular respiration. The electron transport chain between PS II and PS I is made up of the electron carrier plastoquinone (Pq), a cytochrome complex, and a protein called plastocyanin (Pc). this releases free energy that is used to pump protons (H+) into the thylakoid space, contributing to a proton gradient across the thylakoid membrane.
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electrons can take an alternative flow, called cyclic electron flow, uses PS1 but not PS2
when the electrons are in normal orbital, this is the ground state the absorption of photons boost an orbital to higher energy, in an excited state
can not stay in excite state too long, is unstable. the electrons drop back to normal state after a billionth of a second, releasing heat as excess energy.
can also be release as florescence
energy cannot dissapear