lb145 f11 thursday september 29, 2011 class outline
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LB145 F11Thursday September 29, 2011 Class Outline
Photosynthesis• A Carrot (Eyes on the Prize)• Capturing Light• Using Light Energy to Do
Work!
Evidence Supporting Endosymbiont Origin of Mitochondria and Chloroplasts Chloroplast
ribosomes are very similar to eubacterial ribosomes
Chloroplast DNA sequences come out with bacterial DNA sequences in molecular phylogenies
Ancestral photosyntheticeukaryote
Photosyntheticprokaryote
Mitochondrion
Plastid
Nucleus
CytoplasmDNA
Plasma membrane
Endoplasmic reticulum
Nuclear envelope
Ancestralprokaryote
Aerobicheterotrophic
prokaryote
Mitochondrion
Ancestralheterotrophic
eukaryote
Model for Serial Endosymbiosis and the Origin of Eukaryotes
Campbell 8e, Fig. 25.9
Photosynthesis – Minute Paper(worth 1 point)
What is the relationship of the light and dark reactions of photosynthesis? In other words, what things are produced in each set of reactions, and how does one set of reactions depend on the other?
Light
Campbell 8e, Fig. 10-5-4
H2O
Chloroplast
LightReactions
NADP+
PADP
i+
ATP
NADPH
O2
CalvinCycle
CO2
[CH2O](sugar)
Photosynthesis – Connect the two halves!!!
Photosynthesis – Minute Paper (Pt. 2)(worth 1 more point)
What is the relationship of the light and dark reactions of photosynthesis? In other words, what things are produced in each set of reactions, and how does one set of reactions depend on the other?
How does a root cell, in a photosynthetic plant like a carrot, obtain food? How do these root cells use this food?
Photosynthesis
How does a cell at the growing point of a plant root get the energy it needs to grow and divide?
Change the scale of your thinking!Organelle-level
Campbell 8e, Fig. 35-18
Keyto labels
DermalGroundVascular
Cuticle Sclerenchymafibers
Stoma
Bundle-sheath
cell
XylemPhloem
(a) Cutaway drawing of leaf tissuesGuardcells
Vein
Cuticle
Lowerepidermis
Spongymesophyll
Palisademesophyll
Upperepidermis
Guardcells
Stomatalpore
Surface view of a spiderwort(Tradescantia) leaf (LM)
Epidermalcell
(b)
50 µ
m10
0 µm
Vein Air spaces Guard cellsCross section of a lilac
(Syringa)) leaf (LM)(c)
Photosynthetic Leaf Section Organ-level
Plants make sugar in their leaves
How does a cell at the growing point of a plant root get the energy it needs to grow and divide?
Vascular Bundles
Phloem - All plant tissues need sugars made in photosynthetic tissue
Xylem - Stems and leaves need water and minerals from the roots
Sucrose from the leaves is shipped to the roots!
Phloem - sugar transport
• There is phloem in the leaves
• There is phloem in the stems
• There is phloem in the roots
Think about the plant as a whole organism!
Where does it get made?
Where does it get used?
How does it get there?
4
Fig. 36-20
3
2
1
1
2
34
Vessel(xylem)
Sieve tube(phloem)
Source cell(leaf) Loading of sugar
Uptake of water
Unloading of sugar
Water recycled
Sink cell(storageroot)
Sucrose
H2O
H2O
Bul
k flo
w b
y ne
gativ
e pr
essu
re
H2OSucrose
Bul
k flo
w b
y po
sitiv
e pr
essu
re
Sucrose Transport(in plant vascular tissue)
Fig. 35-10e
Sieve-tube element (left)and companion cell:cross section (TEM)
3 µmSieve-tube elements:longitudinal view (LM)
Sieve plate
Companioncells
Sieve-tubeelements
Plasmodesma
Sieveplate
Nucleus ofcompanion
cells
Sieve-tube elements:longitudinal view Sieve plate with pores (SEM)
10 µm
30 µm
Sieve Tubes
Fig. 36-19
Mesophyll cellCell walls (apoplast)
Plasma membranePlasmodesmata
Companion(transfer) cell
Sieve-tubeelement
High H+ concentration CotransporterProtonpump
Low H+ concentration
Key
Apoplast
Symplast Mesophyll cellBundle-sheath cell
Phloemparenchyma cell
SucroseATP
H+
H+ H+
S
S
Sucrose Loading(there’s your co-transporter, in action!)
Why sucrose?
Why sucrose?
ATP is a lousy transport form of energy!
Why sucrose?
ATP is a lousy transport form of energy!
ATP is a lousy storage form of energy!
Chloroplasts are not the only plastids!
How did Engelmann figure this out?
Campbell 8e, Fig. 10.9
Photosynthetic Pigments
Photosynthetic Antennal Complex
Photosynthetic pigments are arranged in an array
Change the scale of your thinking!Organelle-level
Chlorophyll molecules transmit energy from excited electrons in the antenna complex to a reaction center
Photosystem Football Antennal Complex – C106
chairs and tables
Reaction Center – Front Row Team
Primary Electron Acceptor – Help me out!
A Photon of Light – The Football
PHOTOSYSTEM II (Feb 2004) Photosynthesis uses light energy to drive the oxidation of water at an oxygen-evolving catalytic site within photosystem II (PSII). We report the structure of PSII of the cyanobacterium Thermosynechococcus elongatus at 3.5 Å resolution. We have assigned most of the amino acid residues of this 650 kDa dimeric multisubunit complex and refined the structure to reveal its molecular architecture. Consequently we are able to describe details of the binding sites for cofactors and propose a structure of the oxygen-evolving center (OEC). The data strongly suggest that the OEC contains a cubane-like Mn3CaO4 cluster linked to a fourth Mn by a mono-µ-oxo bridge. The details of the surrounding coordination sphere of the metal cluster and the implications for a possible oxygen-evolving mechanism are discussed.Kristina N. Ferreira, Tina M. Iverson, Karim Maghlaoui, James Barber, and So
Iwata (2004) Architecture of the Photosynthetic Oxygen-Evolving Center Science [DOI: 10.1126/science.1093087]
The Z-Scheme
What is the error (or forced misconception) in this diagram?
The Z-Scheme
What is the error (or forced misconception) in this diagram?
The Z-Scheme
What is the error (or forced misconception) in this diagram?
Campbell 8e, Fig. 10-17
Light
Fd
Cytochromecomplex
ADP +
i H+
ATPP
ATPsynthase
ToCalvinCycle
STROMA(low H+ concentration)
Thylakoidmembrane
THYLAKOID SPACE(high H+ concentration)
STROMA(low H+ concentration)
Photosystem II Photosystem I
4 H+
4 H+
Pq
Pc
LightNADP+
reductaseNADP+ + H+
NADPH
+2 H+
H2OO2
e–e–
1/21
2
3
Chloroplast Electron Transport Chain – DOES NOT Yield ATP Directly!!!
Campbell 8e, Fig. 10-17
Light
Fd
Cytochromecomplex
ADP +
i H+
ATPP
ATPsynthase
ToCalvinCycle
STROMA(low H+ concentration)
Thylakoidmembrane
THYLAKOID SPACE(high H+ concentration)
STROMA(low H+ concentration)
Photosystem II Photosystem I
4 H+
4 H+
Pq
Pc
LightNADP+
reductaseNADP+ + H+
NADPH
+2 H+
H2OO2
e–e–
1/21
2
3
Chloroplast Electron Transport Chain: Where does ATP synthesis take place (and why)?
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