Zusammenfassung der Ressource
Photosynthesis
- Occurs in chloroplasts
- Chloroplasts contain
- Their own DNA
- Their own
ribosomes
- Starch grains
- Two Stages
- 1 - Light dependent
- Thylakoid
membrane of
Grana
- Requires
light and
water
- Inputs and Outputs
- Inputs: H2O, NADP
and ADP+Pi
- Outputs: O2
NADPH,
ATP
- Light energy is
used to split H2O
into O, H+ and
free -e
- O2 released
as waste
- Electrons pass along a
chain of molecules giving
energy at each step
(ETC)
- -e Energy is
used to make
ATP
- H+ joins
NADP+ to make
NADPH
- 2- Light independent
(Calvin Cycle)
- Inputs and Outputs
- Outputs: Glucose, NADP ,
ADP+Pi
- Inputs: CO2, NADPH,
ATP
- Occurs in STROMA of
Chloroplast. Depends on Stage
1.
- Inorganic C needs
to be converted to
Organic C
- SO RuBisCo does
this, by bringing a
C molecule from a
CO2 molecule to a
5-C molecule in
the stroma (Rubp)
- Adding the C onto Rubp to make a
6-C molecule makes everything
unstable
- So the 6-C molecule
breaks giving 2 x
3-Carbon molecule
(3-Phosphoclycerate)
- So now, we need
energy. ATP puts
phosphate onto our
3 C molecule and
NADPH pops
some electrons on
- So we have a
high energy 3-C
molecule (G3P)
that can be
converted to
almost any carb
- Some G3P leaves
the cycle and
Glucose is formed
from it and some is
recycled back to
Rubp to continue the
CYCLE.
- Factors Affecting
Photosynthesis
- Light
- Availability affects rate
- Lower light = fewer products
- Wavelength (Wl) and
Intensity affect rate too
- Wl absorbed - depends on
Chlorophyll and accessory
pigments
- At the same Wl, P/s rate will
increase until limited by some
other factor
- Temperature
- Affects
photosynthesis same
way it affects all
enzymes
- High temp, high rate of P/s
- CO2
- Atmospheric CO2 or that
from Cellular respiration
- Low CO2 = Low P/S rates,
because limits Calvin cycle
- Water
- Reduction in H2O =
reduce in P/S rate
because
- Needed as a
reactant in Stage 1
- Stomata will close,
reducing CO2 levels
- Reduces availability of
active sites
- Chemosynthesis
- Some organisms use
chemicals instead of light
to produce the organic
molecules required for life