Zusammenfassung der Ressource
CH 8: Photosynthesis
- Anoxygenic
Photosynthesis
- does not
produce
oxygen
- 4 different bacterial
groups: purple, green
sulfur, green nonsulfur,
and heliobacteria
- releases
sulfur
- Oxygenic
Photosynthesis
- does
produce
oxygen
- in cyanobacteria, 7
groups of algae, ALL
land plants
- photosynthesis
takes place in
leaves
- cells of plant
leaves have
chloroplasts
- CHLOROPLASTS
- GRANA: stacks of
flattened sacs of
thylakoid membrane
- THYLAKOID MEMBRANE:
internal membrane
- contains chlorophyll
and other
photosynthetic
pigments
- pigments clustered
into photosystems
- PIGMENTS
- molecules that
absorb light energy
in visible range
- PHOTON: particle of
light; discrete bundle
of energy
- PHOTOELECTRIC EFFECT:
removal of an electron
from a molecule by light
- 2 types in
green plant
photosynthesis
- CHLOROPHYLLS
- CHLOROPHYLL a
- main
pigment
- directly converts
light energy to
chemical energy
- absorbs
violet-blue and
red light
- CHLOROPHYLL b
- accessory pigment
- absorbs light wavelengths
that chlorophyll a does not
absorb
- CHLOROPHYLL STRUCTURE
- PORPHYRIN RING
- alternating
double and
single bonds
- magnesium
ion center
- photons excite
electrons in ring
- electrons shuttled
away from ring
- CAROTENOIDS
- STROMA: semiliquid
surrounding
thylakoid membranes
- Photosynthesis takes place in 3
stages
- LIGHT DEPENDENT REACTION
- STAGE 2: uses energy to make
ATP and to reduce compound
NADP+ to NADPH
- STAGE 1: captures energy
from sunlight
- LIGHT-INDEPENDENT REACTION
- STAGE 3: uses ATP and
NADPH to power synthesis
of organic molecules
- CARBON FIXATION:
formation of organic
molecules from CO2
- TYPES OF PHOTOSYNTHESIS
- C3
- fix carbon using
the Calvin cycle
- C4
- spatial (place) solution
- fix carbon using
PEP carboxylase in
mesophyll cells
- carbon dioxide is
then released into
bundle-sheath cells
for carbon fixation
by the Calvin cycle
- to produce a single
glucose requires 12
additional ATP
- advantageous in hot dry
climates, photorespiration
removes more than half of
carbon fixed by C3 pathway
- corn, sugarcane, grasses, sorghum
- CAM
- temporal (time) solution
- succulents, cacti, pineapples
- stomata open during
day, close at night
- when stomata closed during
day, organic acids are
decarboxylated to yield high
levels of carbon dioxide
- high levels of carbon
dioxide drive Calvin
cycle and minimize
photorespiration
- fix carbon dioxide using
PEP carboxylase during
night and store in vacuole