Photorespiration, C4, and CAM Flashcards
C3 Plants
The first organic product of carbon fixation is a
3-C compound.
C3 Plants
During hot, dry days…
o Stomata is close
o Decline of CO2 level in the leaves
o O2 level builds up
C3 Plants
During…
o Stomata is close
o Decline of CO2 level in the leaves
o O2 level builds up
hot, dry days
why is stomata closed?
to prevent water loss
C3 Plants
rubp binds with
O2
C3 Plants
Low temperature
___ CO2:O2 ratio
High
C3 Plants
High temperature
___ CO2:O2 ratio
Low
RuBisCO is not loyal to CO2
evolutionary baggage
once O2 binds with RUBP, it produces _____
2-phosphoglycolate
o Toxic to plants
o Inhibits distinct reactions in the Calvin Cycle.
2-phosphoglycolate
o Decreases the photosynthetic output
o Uses ATP rather than generating it
o No sugar produced
o CO2 is lost rather than having it
fixed (50%)
Photorespiration
pros of photorespiration
o photoprotective effects (preventing light-induced damage to the molecules involved in photosynthesis)
o help maintain redox balance in cells
o support plant immune defenses
the first stable molecule formed from the fixation of CO2 is a 4-carbon organic acid.
C4 photosynthesis
common in habitats that are hot, but are less abundant in areas that are cooler.
C4 plants
C4 Photosynthesis
first stable molecule formed from the fixation of CO2 is a
4-carbon organic acid
C4 Plants
Begins in _____ (light-dependent reaction) and is completed in _____ (Calvin Cycle).
mesophyll cells and bundle-sheath cells
is a special structure in the leaves of C4 plants where the tissue equivalent to spongy mesophyll cells is clustered in a ring around the leaf veins outside the bundle sheath cells.
Kranz anatomy
Kranz anatomy
is a special structure in the leaves of C4 plants where the tissue equivalent to spongy mesophyll cells is clustered in a ring around the leaf veins outside the bundle sheath cells.
The C4 Pathway
- In mesophyll cells, the enzyme PEP carboxylase adds CO₂ to PEP, forming a four- carbon compound.
- The four-carbon compound (such as malate) moves into a bundle-sheath cell via plasmodesmata.
- In bundle-sheath cells, an enzyme releases CO₂, which enters the Calvin cycle.
it can fix CO2 even when CO2 concentrations are low
PEP carboxylase
C4 plants expend -___ more ATP
to synthesize 1 molecule of
glucose.
12
The goal is to increase the concentration of CO2
C4 Photosynthesis
CAM
Crassulacean Acid Metabolism
- first observed in Crassulaceae plants
- adaptation to the arid environment
- almost similar to C4
CAM
C4 Plants
during the day, stomata is ___ and
close, release CO2 and conserves water
C4 Plants
at night, stomata is ___ and
open, take CO2
tropical grasses like corn, sugarcane
C4 plants
A type of plant that produce a 4-carbon compound, oxaloacetate
as the first stable product of carbon fixation process
C4 plants
Mesophytic
C4 plants
12 NADPH and 18 ATP are needed for the production of glucose
C4 plants
Mesophyll cells and bundle sheath cells
C4 plants
Fix carbon in Cytoplasm, - attach CO2 to PEP
C4 plants
More energy efficient
C4 plants
Succulents, pineapple, agave
CAM plants
A type of plant that utilize CAM photosynthesis
CAM plants
Xerophytic
CAM plants
12 NADPH and 39 ATP are needed for the production of glucose
CAM plants
Only in mesophyll cells
CAM plants
Fix carbon at night only, fix it to organic molecules
CAM plants
Best water conservation
CAM plants
