Photosynthesis Flashcards
what are the three organelles unique to plant cells?
cell wall
vacuoles
plastids
what are the three types of plastid?
amyoplasts
chloroplasts
chromoplasts
how large are plant cells?
up to 5x the size of animal cells
what is the cell wall composed of ?
polysaccharides
what are unique features of the cell wall?
they mean the plant cell cannot change shape
they mean that the plant cells are firmly fixed to each other
they stop the plant cell ingesting food by endocytosis
the cell wall stops the plant cell bursting osmotically
the cell wall stops attacks by pathogens
why is a plant cell autotrophic?
it makes its own energy as the cell wall prevents ingestion by endocytosis
how big is a cell walls vacuole?
30-50% of the cells volume
what are vacuoles made from?
ER and Golgi
what do vacuoles do for the cell?
they sequester any compounds reaching toxic quantity in the cell
they keep compounds that are toxic to pests
they are important to cell growth without using a lot of energy
they contain digestive enzymes like lysosomes
what are chromoplasts?
plastids that contain pigments
what are amyoplasts?
plastids that store starch
what are proplastids?
the precursor to plastids that can develop into whichever plastid type is needed by the cell
what are the internal structures of a chloroplast?
inner and outer membrane
membrane structures known as thylakoids
granums (stacks of thlakoids)
stroma - the colourless fluid surrounding the granum
copies of parts of their own genome
proteins and structures necessary for proteinsynthesis
can different plastids interconvert?
yes
how many plant proteins are encoded and stored in chloroplasts?
120/2,000 - 5,000
where are most plant proteins synthesised?
the cytoplasm of the cell
what processes make up photosynthesis?
the light reaction and the Calvin cycle
which proteins and pigments are involved in the light reaction?
chlorophyll a, b and carotenoids
what are the stages of the light reaction?
light is absorbed by the light harvesting complexes in the photosystem 2.
this results in 2 electrons aquiring energy
these electrons proceed through the electron transport chain resulting in the production of energy that can be used by the cell
what happens when water is split during the light reaction?
oxygen and H+ are released resulting in the high energy state of the electrons in the photosystem
where is the electron transport chain embedded ?
in the thylakoid membrane
how is NADPH produced?
the electrons reduce NADP+
how is a proton motor force created in the light reaction?
the build up of H+ ions in the thylakoid space from the break down of water plus the addition of H+ ions in the space as a consequence of the movement of electrons
what happens as a consequnce of the proton motor force?
ATP is generated
what are the 3 phases of the Calvin cycle?
carbon fixation
reduction
regeneration of the CO2 acceptor
where does the cavlin cycle take place?
the stroma
what happens during the calvin cycle?
CO2 is fixed and NADP and ATP are regenerated and sugars are synthesised
how are the calvin cycle reactions catalysed?
the enzyme rubisco
how affective is rubisco as an enzyme?
very ineffective hense plant cells have large amounts of it
how can biologists use and improve the photosynthetic pathway?
research into improving the efficiency of rubsico is being done to increase crop yields
