Hydrogen ions, which are used in
CHEMIOSMOSIS to product ATP. These
protons are then accepted by NAD to form
reduced NAD
Electrons to replace those lost by the oxidised
chlorophyll
Non-cyclic photophosphorylation
Light strikes PS2, exciting a pair of
electrons that leave the chlorophyll molecule form
the primary pigment reaction centre
Electrons pass along a chain of electron carriers
and the energy is released to synthesis ATP
Light has also struck PS1 and a pair of electrons is lost
Electrons along with protons, join NAD which becomes
reduced NAD
Electrons from the oxidised PS2 replace the
electrons lost from PS1
Electrons from photolysed water replace those lost by the
oxidised chlorophyll in PS2
Protons from water take part in chemiosmosis to make ATP and
are then captured by NAD, in the stroma.
Light-independent stage
Products if Calvin cycle
Some GP can make amino acids and fatty acids
TP molecules can combine to form
hexose sugars (e.g. Glucose)
Glucose can be used to form fructose
TP can be converted to
glycerol and can combine with
fatty acids to make lipids
Hexose sugars can be
polymerised into other
carbohydrates such as
cellulose and starch.
Limiting Factors
Carbon dioxide concentration
Temperature
Light intensity
Chloroplasts
Structure
Disc shaped and
between 2-10 um long
Surrounded by a
double membrane - an
envelope
Intermembrane space
Outer membrane is
permeable to many
small ions
Innner
membrane
Has embedded
transport proteins
Folded into
lamellae, which
are stacked to
form a granum
Stroma is a fluid-filled matrix.
Reactions of the
light-independent stage occur
here where the necessary
enzymes are located.
Grana are stacks of
flattened membrane
sacs, called
thylakoids. These are
the sites of light
absorption and ATP
synthesis during the
light-dependant
stage.
Adaptations
Inner membrane can
control entry and exit of
substances between
cytoplasm and the stroma
Many grana provide a
large surface area for the
photosynthetic pigments,
electron carriers and ATP
synthase enzymes, all
involved in LI reaction
Photosynthetic pigments are
arranged into photosystems
Keywords
AUTOTROPH - are organisms that use
light energy or chemical energy and
inorganic molecules (CO2 & Water) to
synthesise complex organic molecules
HETEROTROPHS - are organisms that ingest
and digest complex organic molecules,
releasing the chemical potential energy stored
in them.