AP Biology 2 Notes Chapter 10 Photosynthesis. Introductory Vocab Heterotrophs Autotrophs...
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Transcript of AP Biology 2 Notes Chapter 10 Photosynthesis. Introductory Vocab Heterotrophs Autotrophs...
AP Biology 2
Notes Chapter 10
Photosynthesis
Introductory Vocab
• Heterotrophs
• Autotrophs
• Chemoautotrophs
• Mesophyll
• Stroma
• Grana
• Thylakoids
PHOTOSYNTHESIS
• The equation: – CO 2 + H 2 O C H 2 O + O 2
• Light reactions (photo) occur in thylakoids– Changes light energy to chemical energy
making NADP and ATP
• Calvin cycle (synthesis) occurs in the stroma– Uses the NADP and ATP to make sugar
Label the Parts
Light Review
• Wavelength
• ROYGBIV
• Photons
• Beneficial for photosynthesis
• Reflection and absorption in plants
• Spectrophotometer
Chlorophyll
• Chlorophyll a
• accessory pigments
• Chlorophyll b
• Carotenoids
Chlorophyll Molecule
Photosystems
• Chlorophyll is organized into photosystems
• These include an antenna complex, reaction center chlorophyll and a primary electron acceptor
• Photosystem I - contains chlorophyll a and makes NADPH
• Photosystem II makes ATP
Converting light energy to chemical energy
Light Energy
Light Energy
Electron Flow
• Non cyclic electron flow – occurs in thylakoids and uses both photosystems
– Passes electrons from water to NADPH
– Produces ATP and NADPH and oxygen by splitting water
• Cyclic electron flow– makes only ATP and uses Photosystem II
– This ATP will be used in the Calvin cycle
Chemiosmosis Differences
• MITOCHONDRIA• Electrons come from
food• Membranes pump
protons
• CHLOROPLAST• Uses light energy• Thylakoid membrane
pumps protons from stroma to thylakoid compartment and back
Light Reactions and Chemiosmosis
Chemiosmosis Similarities
• Both mechanisms:– work with ATP synthetase to produce ATP
from ADP– have similar electron carriers– ETC moves protons across a membrane down
an electromagnetic gradient
Calvin Cycle
• Similar to Krebs because the starting material is regenerated
• Carbon enters as CO 2 and leaves as sugar
• Produces G3P
• Uses ATP
3 Phases of Calvin Cycle
• Carbon Fixation– CO2 attaches to ribulose biophosphate (RuBP) which
is the starting material– Rubisco is the enzyme that catalyzes this step
• Reduction– Transfers a P from ATP to another molecule– Removes electrons from NADPH
• Regeneration of RuBP– Uses 3 ATP molecules to make 1 RuBp
Calvin Cycle Summary
• To produce one 6 carbon sugar (glucose) it takes 18 ATP and 12 NADPH!
• The cycle must turn 6 times to make 1 glucose
Photorespiration• Occurs on very hot dry days• Occurs in C3 plants like rice, wheat and soybeans
• Rubisco can accept O2 to make a 2 carbon molecule which the mitochondria and perioxisomes can change to CO2
• This produces not ATP or food• Uses Calvin cycle products• Seems useless but probably left over from day when there
was more CO2 in air
• Reduces production of crops
C4 plants• These include sugar cane and
corn
• Works in very hot, dry regions
• This keeps the plant from going through photorespiration
• PEP carboxylase attaches to CO2 more easily than rubisco
• When CO2 levels are low, this
can change CO2 even when rubisco cannot
CAM plants• Cacti, pineapple
• Occurs in very dry regions
• These open the stomata only at night to go through photosynthesis…but no light!!
• Bring in CO2 during the night and change to an organic acids that is stored in the vacuoles
• During light, organic acids are released and changed back to CO2