Bio CH 8
Terms
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- Photons
- small particles of energy. Energy of a photon is inversely proportional to wavelength.
- Excited state
- when a molecule absorbs a photon of light energy, one of its electrons becomed energized, which means that the electron shifts from a lower-energy atomic orbital to a higher energy orbital- distant from the atomic nucleus.
- Ground state and fleuresnce
- The condition in which all of its electrons are in their normal, lowest-energy levels. Its energy dissipates as heat or an emmision of light if a loner wavelength than the absorbed light-fluroesence.
- excited state and photosynthesis
- the excited electron may leave the atom and be accepted by an electron acceptor molecule, ehich becomes reduced in the process.
- Chloraplast structure
- The innermembrane encloses a fluid-filled region called the stroma (which conatins the enzymes). Disc-like sacs called thylakoids. The thylakoid membrane encloses a fluid-filled interior space, thylakoid lumen. Stacks of thylakoids are grana.
- chloraphyll
- absorbs light in the red and blue regions of the spectrum. Has a ring-porphyrn that absorbs light energy, long side chain that makes it non-polar.
- carotenoids
- yellow & orange. absorb different wavelenghts. Protect chloraphyll.
- Light-dependent rcns
- the energy from sunlight phosphorylates ADP and reduces NADP+
- Photosystems
- In the thylakoid membrane, chlorapyhll molecules are grouped into these clusters.
- Rcn center chloraphylls
-
P700- PS1
P680-PS2 - P700 and P680 & e-
- at the center, an e- is raised to an excited state, and this hi-energy electron is transferred to an e- acceptor.
-
Noncylcic e- transport
(ps I) -
(1) chloraphyll molecule absorbs a photon.
(2) An e- in P700 is excited
(3) The e- is passed along an ETC
(4) The last acceptor is ferredoxin.
(5) this transfers the e- to NADP+.
(6) NADPH is then released into the stroma
(7)Photosystem 2 donates an electron to P700 - P680 and its electron hole
-
Photolysis of H2O
(1) P680 has a molecule so strong it can pull e- from H2O.
(2) water is broken down into 2e-, 2 protons, & 1/2 O2.
(3) Each e- is donated to P680
(4) protons released into thylakoid lumen. - Calvin cycle
- Co2 uptake, Carbon reduction, RuBP regeneration
- CO2 uptake
-
(1)CO2 reacts with RuBP, catalyzed by rubisco.
(2)2 molecules of PGA produced. - Carbon reduction
- Reducing power from ATP and NADPH are used to convert PGA molecules to G3P.
- RuBP regeneration
- 2 G3P molecules are removed. 30 carbons all rearrange into 6 molecules of RuBP.