Module 5.6 Flashcards
Photosynthesis
what is the relationship between respiration and photosynthesis
the products of one are the raw materials for the other
respiration removes oxygen and adds carbon dioxide photosynthesis removes carbon dioxide and adds oxygen
components of a chloroplast
outer membrane
inner membrane
lamellae
grana
thylakoid
stroma
DNA
what is the envelope
the outer and inner membrane with the intermembrane space
the outer membrane is highly permeable
What is the stroma
fluid filled matrix
contains the enzymes needed to catalyse the reactions of the light-independent stage of photosynthesis
also has starch grains, oil droplets, small ribosomes and DNA
What are the grana
stacks of thylakoid membranes
where the light-dependent stage of photosynthesis occurs
make big surface area for distribution of photosystems, electron carrier and ATP synthase
What is a thylakoid
less permeable and folded into a flattened discs that form stacks
thylakoid membrane is less permeable
creates compartment of thylakoid space
holds photosystems
what are the lamellae
the thylakoids within one granum may be connected to thylakoids within another granum by the lamellae
what is a photosynthetic pigment
absorbs light of a particular wavelength for light harvesting in photosynthesis
where are photosynthetic pigments located
primary pigment reaction centre contains chlorophyll 700 or 680
accessory pigments are around the funnel of the photosystem
what is photolysis
the splitting of water molecules using light energy
creating 1/2 o2 and 2 protons
what happens when light strikes PSII - non cyclic
the photons energy is channelled to the primary pigment reaction centre
the light energy excites a pair of electrons in the chlorophyll molecule
what happens to the electrons after they are excited from PSII - non cyclic
the energised electrons escape from the chlorophyll molecule and are captured by an electron carrier
the electrons are replaced by electrons derived from photolysis
how do electron carriers work
they contain an Fe 2+ ion which can accept and donate the electrons becoming reduced and re-oxidised to pass the electron to the next carrier in the chain
what are electron carriers
proteins with iron at its centre embedded in the thylakoid membrane
how is the electron carrier used - non cyclic
as electrons are passed along the chain of carriers some energy associated with the electrons is released
this energy is used to pump protos across the thylakoid membrane into the thylakoid space creating a proton gradient
what happens at PSI - non cyclic
the electrons from the electron carrier chain are captured by another molecule of chlorophyll in PSI replacing those lost from excitation from light energy
what does ferredoxin do - non cyclic
accepts the electrons from PSI and passes them to NADP in the stroma
what does the proton gradient do - non cyclic
the protons diffuse down their concentration gradient through channels in the thylakoid membrane associated with ATP synthase
the flow of protons causes ADP and inorganic phosphate to join forming ATO
What does NADP reductase do - non-cyclic
catalyses the reaction to form reduced NADP from NADP accepting protons and electrons in the stroma
products of the light dependent stage - non cycluc
ATP and reduced NADP
what happens in cyclic phosphorylation
light strikes PSI
a pair of electrons in the chlorophyl molecule become excited
they escape and pass to an electron carriers system then pass back to PSI
products of cyclic phosphorylation
the passage of electrons along the electron carriers generates a small amount of ATP but not photolysis of water occurs so no protons or oxygen are produced and no reduced NADP is generates
what does RuBisCO do in the calvin cycle
catalyses the reaction between carbon dioxide and ribulose bisphosphate (RuBP) which is a five carbon compound
what does the reaction of carbon dioxide and RuBP form
an unstable intermediate six carbon compound that immediately breaks down into two molecules of GP
