5.2 Flashcards
cyclic photophosphorylation
light hits photostems
electrons are excited to a higher energy level and leave the photostem
the excited electrons pass along the etc releasing energy
the energy provides energy for chemiosmosis
H+ ions are actively pumped from low conc in stroma to high in thylakoid forming conc gradient
H+ ions diffuse back across the thyl.. into stroma via ATP synthase enzymes
movement of H+ cause ATP synthase to catalyse the production if ATP
electrons rejoin photosystem at end of electron transport chain in a cycle
ATP produced enters the light independent reaction
non-cyclic photophosphorylation
light energy hits photostem 2 in thylak..
two electrons gain energy- exited- higher
excited leave photostem and pass to etc
they are replaced by electrons from the photolysis of water
energy is released which allows chemiosmosis
H+ ions are actively pumped from low conc in stroma to high in thylakoid forming conc gradient
H+ ions diffuse back across the thyl.. into stroma via ATP synthase enzymes
movement of H+ cause ATP synthase to catalyse the production if ATP
at the end of etc electrons are passed from photostem 2 to 1
light energy hits photostem 1 exciting another pair of electrons which leave
then pass along etc
then combine with H+ ions from photolysis of water and NADP to form reduced NADP
reduced NADP and ATP passes to light independent reactions
light dependant
Thylakoids of chloroplast which contain chlorophyll
* Photons hit chlorophyll which becomes excited
(raised to a higher energy level)
* Two high energy electrons are emitted
* Electrons pass down ETC on thylakoid membrane
* ATP is synthesised by photophosphorylation
* Energy is used for photolysis (splitting of water) to
produce two electrons (replace those lost from
chlorophyll, protons and oxygen
* Electrons are used to reduce NADP to NADPH
* NADPH and ATP are used in the Light Independent
reaction.
* Oxygen is released into the atmosphere.
hydrogens build up in thylakanoids
light-independent
calvin benson cycle
atp and reducted natp used
co2 fixed
co2 converted to glucose
occurs in stroma of chloroplasts
calvin benson cycle
co2 diffuse into stroma
ribulose biphosphate (RuBP) binds to and carbon fixes CO2 5c
catalysed by the enzyme rubisco
-highly unstable 6c compound is formed which immediately splits into two molecules of 3c glycerate 3phospate (gp)
ATP and NADPH are used to reduce gp into glyceraldehyde 3 phosphate (galp)
some is used to make carbohydrate but most makes rubp so cycle can continue
for every glucose produced 5 molecules of rubp are made
autotroph
organism which makes complex organic compounds from simple inorganic compounds
heterotroph
organism that obtains complex organic compounds by feeding on other organisms dead remains
photosynthesis
converts light energy into chemical
light energy is used to split bonds in water
O2 released as a waste product
hydrogen combined with carbon dioxide to form glucose
photosynthetic pigments
chlorophyll a
chlorophyll b
-similar action and absrobstion spec
carotenoids
absorbtion spectrum
absorption of light compared to wavelength
action spectrum
rate of photosyntehsis against wavelength
rf
distance of solute (colour) / distance of solvent
rate limiting factors of photosynthesis
light - affects the amount of chlorophyll excited
co2 - calvin cycle
temp - controlled enzymes
importance of thylakoid membranes
contains photostems so light can be absorbed
contains carrier proteins so hydrogen pumped into thylakoid space
contains atp synthase so hydrogen can pass through
membranes form a barrier so H+ ions can accumulate
membranes are the site of chemiosmosis
units for photosynthesis
umol - galp produced
m^-2 - area of leaf
sec^-1- in one second
