Chapter 10
photosynthesis: converts light energy to chemical energy
Light reactions convert solar energy to chemical energy
Calvin cycle uses ATP and NADPH to reduce CO2 to sugar
alternative ways of carbon fiction have evolved in hot climates
eukaryotes that are autotrophs make photosynthesis from chloroplast
chloroplast contains thylakoids
photosynthesis: 6CO2+12H2O+light energy-> C6H12O6+6O2+6H2O
chloroplast splits H2O into water and hydrogen
photosynthesis is a redox process
splits water, releases O2, creating ATP, and forms NADPH
Calvin cycle- forms sugar from CO2, uses ATP for energy and NADPH for reducing power
light is a type of electromagnetic energy
colors we see- visible light
wavelengths- drive photosynthesis
pigment- absorbs light on specific wavelengths
chlorophil- main photosynthetic pigment in plants
photon- boosts pigments of light to create high energy orbitals
photosystem- composed of reaction center complex which are surrounded by light harvesting complexes that funnel energy of protons
primary electron acceptor- special reaction center molecules absorb energy electron are boosted and transferred here
photosystem II- contain molecules for reaction center system
photosystem I- contain p700 molecules
linear electron flow- produces NADPH, ATP, and oxygen during light reactions
cycle electron flow- allows only one photosystem, making ATP but nothing else
chemiosmosis
electrons transport chains to generate H+, uses this to make ATP
occurs in stroma
uses electrons from NADPH and energy from ATP
one molecule of G3P exits cycle per three CO2
CO2 is converted into glucose and other organic molecules
some plants are capable of closing their stromas to conserve their water
Rubisco binds O2 instead of CO2
keeps CO2 out and O2 in
photorespiration occurs
consumes ATP and releases CO2
C4 plants minimize cost of photorespiration by using CO2 in four carbon compounds
bundle sealth cells- export the four carbon compounds , release carbon dioxide for use in Calvin cycle
CAM plants open their stomata at night, using CO2 into organic acids which are stored in mesophyll cells
stomata closes in the day and CO2 is released from organic acids for Calvin cycle
organic compounds made in photosynthesis provide energy and building material for ecosystems
all of life depends on photosynthesis