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= LHCs. Reminder from last Lecture. The structure/function of Chl a -dominated PS I and PSII reaction centers is the same in all phytoplankton groups.

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Reminder from last Lecture

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Reminder from last lecture

= LHCs

Reminder from last Lecture

The structure/function of Chl a-dominated PS I and PSII reaction centers is the same in all phytoplankton groups.

However, outer LHCs associated with these PS I and PS II antenna vary depending upon taxonomic group and give phytoplankto their characteristic colors. Eg. Red Tide Dinoflagellates

Alexandrium

Dinoflagellates in coastal Red Tide

2 LHCs = some Chl a-Chl c- protein complexesLots of Peridinin-Chl a- protein complexes


Reminder from last lecture

Photosynthesis Light-Dependent Reactions and Bio-optical Measures of Primary Production

LHCs

For PSI

NADPH2

=

H+

Chemical electron acceptor

Chemical electron acceptor

NADPH

Light-Harvesting

Pigment-protein

Complexes (LHCs)

For PS II

e

PS I

Ejects electron

Ejects electron

PS II

680

IEC

e

IEC

Light Harvesting

Chl a-protein complexes

e

IEC

e

4e

Light Harvesting

Chl a-protein complexes

For every 8 photons absorbed, 1 O2 molecule “evolved”

4e

e

2H2O

H2O splitting complex

O2 + 4H+

Predictive Modeling is based upon Mechanistic Understanding

Stroma (fluid outside the thylakoids but inside the chloroplast)

INTERMEDIATE ELECTRON CARRIERS (IECs)

Lumen ( fluid in fully enclosed space inside the thylakoids)


Reminder from last lecture

Phytoplankton pigmentation evolved to absorb different types of UWL fields.

Measure of Spectral Irradiance, QPAR(l)z = PFD= how many photons available for PS

Measure Phyto absorption spectrum, aph(l) = what kinds of photons can be absorbed

(cDOM)

QPAR(l)z x aph(l) = QPHAR(l), photosynthetically absorbed radiation

= number of photons absorbed to drive photosynthesis

(particles)

QPHAR(l)

= maximum number of O2 molecules that could be evolved

8

aph(l)

QPAR(l)

QPHAR(l)

For each photon of QPHAR(l), 1/8th or 0.125 molecules of O2 will be evolved

= maximum quantum efficiency for photosynthesis (fmax)


Reminder from last lecture

Bio-optical estimation of rates of primary production based upon optical measures only

Rate of Primary Production

= PP (umoles O2 evolved/mg Chl/hr), used to get phyto plankton specific rates

= PP (umoles O2 evolved/m3/hr), used to get volume specific rates

= PP (umoles O2 evolved/m2/hr), used to get integrated water column rates

Upper limit of PP z,t = QPAR(l)z,t x aph(l z,t) x fmax z,t

Where max = 0.125

Caveat: in situ f at depth z and time t = operational fz,t is often much less than 0.125 and highly variable depending upon environmental and cellular conditions.

Today’s great challenge: Hunt for methods to measure/predict in situ fz,t

Underwater gliders

Satellite: MODIS-AQUA Absorption Products (APS)

Optical moorings


Reminder from last lecture

Photosynthesis Light-Dependent Reactions and Bio-optical Measures of Primary Production

LHCs

For PSI

NADPH

=

H+

Chemical electron acceptor

Chemical electron acceptor

NADP

Light-Harvesting

Pigment-protein

Complexes (LHCs)

For PS II

e

PS I

Ejects electron

Ejects electron

PS II

680

IEC

e

IEC

Light Harvesting

Chl a-protein complexes

e

IEC

e

4e

Light Harvesting

Chl a-protein complexes

For every 8 photons absorbed, 1 O2 molecule “evolved”

4e

e

2H2O

H2O splitting complex

O2 + 4H+

Stroma (fluid outside the thylakoids but inside the chloroplast)

INTERMEDIATE ELECTRON CARRIERS (IECs)

Lumen ( fluid in fully enclosed space inside the thylakoids)


Reminder from last lecture

Chemical energy

Reducing Power

LHCs

For PSI

PO4

PO4

3

ADP

2

ATP

PO4

NADPH

PO4

PO4

=

H+

Pi =PO4

Chemical electron acceptor

NADP

H+

H+

e

PS I

Ejects electron

IEC

e

IEC

e

IEC

e

Light Harvesting

Chl a-protein complexes

H+

H+

H+

O2

H+

H+

H+

photophosphorylation


Reminder from last lecture

Photosynthesis (PS)

Light reactions = Light dependent reactions

Dark reactions = Light-independent reactions

Optional review/details www.steve.gb.com/science/photosynthesis.html


Reminder from last lecture

Generally 1 O2 molecule is evolved for 1 CO2 molecule fixed

Gross Photosynthesis

Respiration

Gross Photosynthesis - Respiration = Net Photosynthesis (growth potential)


Reminder from last lecture

Measuring Gas Exchange to estimate Photosynthetic rates and Primary Production.

When photosynthesis rates from several experiments are plotted against light intensity, the result is a photosynthesis light response curve

O2 evolution (PSII)

C02 uptake/fixation

(Calvin cycle)

P -I (photosynthesis-irradiance) curve = P-E (photosynthesis -energy) curve

Why do all P-I curves first increase in proportion to increasing irradiance and then level off to an upper limit = maximum rate of photosynthesis?


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