Class 5 Flashcards
photosynthesis powers the cellular processes in the plant and downstream, the main – of organisms and ecological processes
energy source
ligher reactions are also called the – reactions
thylakoid
carbon (fixation) reactions are also called the – reactions
dark
the bulk of photosynthesis takes place in the leaf – which has cells with many chloroplasts
mesophyll
chloroplasts have high concentration of light-absorbing – pigments called chlorophylls
green
light reactions occur in the –
internal membranes (thylakoid)
carbon reactions occur in the – of the chloroplast, the aqueous region surrounding the thylakoids
stroma
light reactions lead to the splitting of –
water
light reactions produce – and – (reducing equivalents and energy) to be provided to the carbon reactions
ATP and NADPH
light is an – wave and many kinds of light exist = many wavelengths (or frequencies)
electromagnetic
light is also a particle so it contains –
energy (i.e. impact)
sunlight is a stream of – of different frequencies
photons
plants can only use a narrow range of wavelengths for photosynthesis, the same range as the human eye,
visible spectrum, 400-700 nm
an – of a substance quantifies its ability to take up light across the spectrum
absorption spectrum
absorption spectrum plots a substance’s absorption of light against – of light
wavelength
absorption of light energy by pigment molecules takes place when the photon causes an electron to move to a higher energy state; the molecule becomes –
excited
as a chlorophyll molecule returns to its less excited state, it releases the energy by emitting –, energy transfer, or photochemistry
heat, fluorescence,
fluorescence involves – a photon of lower energy (longer wavelength)
re-emitting
energy transfer causes the – of another pigment
excitation
photochemistry causes – to occur
chemical reactions
photosynthetic pigments include chlorophylls (and – in certain bacteria), and carotenoids and other accessory pigments
bacteriochlorophylls
photosynthetic pigments are rich in – which stabilize the excited state
conjugated double bonds
chlorophyll a and chlorophyll b are made up of a complex ring structure called – (similar to in hemoglobin)
haem group
a harm group contains a – atom bonded to nitrogen
Mg
a harm group contains a long – that holds the pigment anchored to a protein or membrane
hydrocarbon tail
carotenoids are linear molecules which give a – color
orange
carotenoids are intimately associated with the – and with photosynthetic proteins
thylakoid membrane
light absorbed by the carotenoids is transferred to chlorophyll for photosynthesis and thus carotenoids are –
accessory pigments
carotenoids also help protect from –
excess light damage
plots of the response of a system (i.e. products generated in a reaction) against light wavelength (used to study light-driven reactions)
action spectra
an action spectrum will show what – of light can cause the reaction to proceed
wavelengths
light absorption in the chloroplasts is primarily done by chlorophyll in the –
antenna complex (light-harvesting antenna)
antenna complex transfers the absorbed energy to chlorophyll in the –
reaction centers
because bright light is – even without an antenna, many reaction centers would be activated only intermittently
dilute
having – of the chlorophyll in the antenna allows the reaction centers to run continuously
> 95%
red drop effect showed that only – light was inefficient in driving photosynthesis despite high absorption of this wavelength
far-red
enhancement effect showed a major enhancement of photosynthesis when – together were supplied, relative to when either were supplied alone
red and far-red
photosystem – preferentially absorbs far-red light
I
photosystem – preferentially absorbs red light and is driven very poorly by far-red light
II
Z scheme is constituted of two photosystems each with its own antenna pigments and photochemical reaction center linked by an –
electron transport chain
stacked thylakoids
grana lamellae
unstacked thylakoids
stroma lamellae
T/F: chloroplast is bounded by two lipid bilayer membranes, the inner and outer envelope
true
chloroplast contains its own –
DNA, RNA, and ribosomes
some chloroplast proteins are produced within the chloroplast itself whereas others are encoded by nuclear DNA and produced in the – and imported into the chloroplast
cytoplasm
T/F: some chloroplastic enzymes are composed of protein sub unites encoded from both nuclear and chloroplast DNA
true
proteins embedded in the thylakoid membranes, via hydrophobic amino acids, with regions extending into surrounding aqueous medium are called
integral membrane proteins
reaction centers, the antenna pigment/protein complexes and most of the – proteins are integral membrane proteins
electron carrier
photosynthetic pigments are associated in a – but highly specific way with proteins forming pigment-protein complexes
noncovalent
pigment-protein complexes are organized within the – to optimize energy transfer in antenna complexes and electron transfer in and between reaction centers
membrane
photosystem I and Ii are – in the thylakoid membrane
spatially separated
PSII located in
grana lamellae
PSI located in
stroma lamellae
ATP synthase enzyme is located in
stroma lamellae
– that connects the two photosystems is evenly distributed between the two photosystems
cytochrome -b6f complex
diffusible electron carriers – and – deliver the electrons between photosystems
plastocyanin and plastoquinone
plants usually have an excess of PSII to PSI usually a ratio of about –
1.5 : 1
the antenna system delivers energy efficiently to the –
reaction centers
there are – chlorophylls per reaction centers in higher plants
200-300
diverse antenna pigments are involved, all associated with the –
thylakoid membrane
energy is transferred from the antenna to the reaction center by – resonance energy transfer
fluorescence resonance
the energy transfer to the reaction center occurs by a – process such as the transfer of energy between tuning forks
nonradiative
the sequence of pigments within the antenna shifts progressively toward –
longer red wavelengths (lower energy)
some – is dissipated during energy transfer
heat
since heat is lost, energy at the outside of the antenna is – than near the reaction center; this keeps the energy transfer moving one way
higher
most abundant antenna proteins
light-harvesting complex II proteins
light-harvesting complex II proteins bind – chlorophyll molecules
14
photons excite the chlorophyll of the reaction centers, – an electron
ejecting
after excitation, the ejected electron then passes through a series of electron carriers, eventually reducing – and generates ATP
reducing NADP+
photosystem II oxidizes water to oxygen in the –
thylakoid lumen
when PSII oxidizes water it releases – into the lumen
protons
when PSII oxidizes water it passes electron to the plastoquinone, forming –
plastohydroquinone
– oxidizes plastohydroquinone
cytochrome b6f
cytochrome b6f delivers electrons to –
plastocyanin
PSI oxidizes –
plastocyanin
PSI passes electrons to – which reduces NADP+ generating NADPH
ferredoxin
ATP synthase produces ATP as protons diffuse through it from – to –
lumen to stroma
light excites a reaction center chlorophyll by direct absorption or more frequently via – from an antenna pigment
energy transfer
the absorbed photon causes an electron – in the reaction center
rearrangement
P680
PSII
P700
PSI
PS II has its electron supplied by a
donor Yz
donor Yz has its electron supplied by the –, an enzyme that splits (oxidizes) water
oxygen-evolving complex
Mn is an essential –
co-factor
from the cytochrome b6f complex, one electron moves linearly toward –
plastocyanin (PC)
from the cytochrome b6f complex, one electron goes through a –, which effectively pumps more protons into the thylakoid lumen
cyclic process
plastoquinone distributed on the
grana thylakoids
plastocyanin distributed on the
stroma thylakoids
cytochrome b6f complex is – distributed between the grana and stroma thylakoids
equally
Q, PC, and cytochrome b6f are large complexes that are embedded in the –
membrane
Q and PC are –, relatively small molecules
mobile
Q is – soluble moving in the membrane
lipid
PC is – soluble moving in the thylakoid lumen
water
PS I has its electrons resupplied by –
PC
a core – is an integral part of the reaction center
core chlorophyll
under certain conditions, cyclic electron flow occurs, in which – passes electrons back to the cytochrome b6f complex, which results in more protons pumped into the lumen
PS I
some herbicides – electron transport
block
– blocks reduction of the plastoquinone acceptor
DCMU
– competes with ferredoxin acceptors of PS I
paraquat
ATP synthesis during the light reactions is known as –
photophosphorylation
photophosphorylation occur via – mechanism
chemiosmotic
the accumulation of H+ in the lumen (i.e. acidification of the lumen) creates a chemical and electric gradient known as the – force
proton-motive
main light harvesting pigments for photosynthesis
chlorophylls
integral membrane proteins are – arranged in the membranes (they have a unique orientation)
asymmetrically
every year about – tons of CO2 are converted to biomass via photosynthesis
200 billion
starch
storage
sucrose
transport of energy
sucrose is a disaccharide composed of
fructose and glucose
generation of UDP glucose requires
UTP
starch is a – of glucose
polymer
generation of ADP-glucose requires
ATP
during the day, the – will drive the synthesis and storage of starch
accumulation of sucrose
at night, starch is broken down into sugars in the chloroplasts and sugars are exported out of the chloroplast for –
sucrose production
these of ATP as an activator of starch synthesis and UTP as an activator of sucrose synthesis keeps these reactions
compartmentalized
starch and sucrose synthesis can be activated and deactivated –
separately
during the – both sucrose and starch synthesis can occur
day
which synthesis occurs most depends on the – from the cell due to phloem transport
sucrose depleted
buildup of – in the cell will drive starch production
sucrose
during night, – synthesis is inhibited
starch
during –, starch breakdown occurs and sucrose production continues
night
many cells grow at –
night
growing cells utilize sugars derived from sucrose in the –
phloem