Chapter 10: Photosynthesis Flashcards
What is the equation of photosynthesis?
6CO2+6H20+light–>C6H1206(glucose)+602
How does CO2 enter?
through stomata
How is water added?
from soil
Where does O2 come from?
H20
What are the two pathways of photosynthesis?
- Light reactions
2. Calvin-Benson cycle (Dark reactions)
Light reactions
convert light energy into chemical energy in the form of ATP and NADPH+H+
Calvin-Benson cycle (Dark reactions)
CO2 and ATP plus NADPH+H+ produced in light reactions are used in the Calvin-Benson cycle to produce sugars
What are some properties of light?
Light is a form of electromagnetic radiation: it exists as photons which exhibit wave-like properties
; the energy content of a photon is inversely proportional to the wavelength of the light
What’s the order of the electromagnetic spectrum?
Cosmic/gamma rays–>X-rays–>UV–>visible(ROYGBIV)–>IR–>microwaves
Absorption spectrum
each molecule has this; for a particular atom can only absorb photons corresponding to the atom’s available electron energy levels
What are Chlorophylls a and b?
Predominant pigments in green plants chlorine ring containing Mg2+, and a hydrocarbon tail chlorophylls absorb blue and red wavelengths
What are accessory pigments?
absorb photons in the region between blue and red cartenoids
What is the reaction for chlorophyll excitation?
Chl+ + A –> Chl+ + A-
What happens in the chlorophyll excitation?
excited electron shuttled along series of electron-carrier molecules in photosynthetic membrane–>at proton-pumping channel, proton translocation occurs, resulting in ATP synthesis by chemiosmosis
What is photosystem I?
reaction center containing a chlorophyll a (P700) wavelength absorption
What is photosystem II?
reaction center containing a cholorphyll a (P680) wavelength absorption; requires more energetic photons than I
What does that graph on slide 18 show?
That two photosystems are required for noncyclic electron transport.
What is noncyclic electron transport?
Uses photosystems I and II to produce NADPH + H+ together with ATP. Electrons from H20 replenish chlorophyll molecules which gave up electrons. O2 is a byproduct of the breakdown of H20
What is the general pathway of noncyclic electron transport?
Photosystem II (1/2O2 & 2H+ formed)–>Electron Transport (ATP is generated)–>Photosystem I–>Fd–>NADP+ reductase (NADPH formed)
What does cyclic electron transport form?
ATP but not NADPH
What does electron transport do?
electrons are returned to electron-deficient chlorophylls - no O2 is produced; produces additional ATP for reactions in the Calvin-Benson cycle
What is the pathway of cyclic electron transport?
Electron goes to P700 photosystem I, excites –>Fd–>Electron Transport–>electron
How do chloroplasts form ATP by chemiosmosis? (Slide 25)
electrons move through a series of redox reactions, releasing energy–>allows protons to be pumped across the thylakoid membrane from the stroma–>a pH gradient is established (proton-motive force)–>ATP synthase couples diffusion of protons back to the stroma with ATP synthesis
What is the arrangement of atoms in Photosystem II?
4 manganese, 5 oxygen, 1 calcium atom are linked in cluster on which water is split
