Structure of plant cell

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Structure of plant cell
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A modern version of the fluid-mosaic membrane
model
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Longitudinal section through a plasmodesma.
Plasma membrane (PM), endoplasmic reticulum (ER),
cell wall (CW)
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TEM showing the nucleus (N) of a bean root tip
cell. Note the two membranes of the nuclear
envelope (NE) and the large central nucleolus (NU)
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TEM of a nuclear envelope (NE) with nuclear pores
(NP). The continuity of the inner and outer
membranes becomes apparent where the membranes
are seen in cross-section
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(A) Diagram of a nuclear pore complex in a
nuclear membrane. (B) TEM showing a tangential
thin section through nuclear pore complexes of a
tobacco root tip cell.
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TEM showing a chloroplast with stacked grana (GT)
and unstacked stroma (ST) thylakoids in a maize
leaf mesophyll cell. The dark granules are
plastoglobuli,lipid droplets that stain strongly
with osmium.
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Diagram depicting the three-dimensional
organization of mitochondrial cristae and the
distribution of ATP synthase molecules in the
inner membrane
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TEM depicting a longitudinal section through a
transfer cell mitochondrion showing numerous
cisternae and mitochondrial ribosomes (arrows),
which are smaller than cytoplasmic ribosomes.
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(A) A three-dimensional molecular model of the
Type ?wall shows the molecular interactions
between cellulose, XyG, pectins, and wall
proteins. (B) A three-dimensional molecular model
of the Type ?wall shows the molecular
interactions between cellulose, GAX, pectins, and
aromatic substances.
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Biosynthesis of the wall requires a coordination
of the synthesis of cellulose microfibrils at the
plasma membrane surface, with the synthesis and
glycosylation of proteins and wall-modifying
enzymes at the rough ER and the synthesis of all
noncellulosic polysaccharides at the Golgi
apparatus.
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Structure of the core subunits of the
mitochondrial ATP synthase, an F-type H-ATPase
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Ca2 signaling coordinates the activities of
multiple ion channels and H-pumps during
stomatal closure.
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Struchure of an aquaporin showing the six
thansmembrane helices and two conserved NPA
(Asn-Pro-Ala) residues.
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Ribbon diagram of the tubulin dimer within a
microtubule, resolved at 0.37 nm.
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(B) Diagrams of a microtubule in cross-section
and side view. (C) Electron micrograph of a
microtubule in cross-section from a plant cell,
showing thirteen protofilaments. (D) Electron
micrograph of a microtubule assembled from
purified tubulin and viewed from the side.
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Sites for protein synthesis in a plant cell. A
typical plant cell synthesizes proteins in three
distinct compartments-the cytosol, plastids, and
mitochondria.
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(A) Schematic diagram of plant chloroplast,
showing compartmentation of the organelle. (B)
Transmission electron micrographs of plant
chloroplast reveal its ultrastructure.
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Structures of chlorophylls
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Structural model of the PS? reaction center, a
schematic representation showing the structure
dominated by the tow PS? reaction center proteins
D1 and D2.
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Structure model of the PS? reaction center, a
schematic representation showing the organization
of the two major proteins in this complex, the
psaA and psaB subunits, designated here as A and
B.
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Lateral heterogeneity of the chloroplast membrane
complexes
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The current Z-scheme, showing Em values of
electron carriers. The vertical placement of each
electron carrier of the noncyclic electron
transfer chain corresponds to the midpoint of its
redox potential.
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Membrane organization of the Z-scheme. The
components of the chloroplast electron transport
chain and the ATP-synthesizing apparatus are
illustrated in the thylakoid membrane.
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Organization of the protein subunits of the
cytochrome b6f complex.
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Sites of action for the inhibitors of the
chloroplast electron transport chain. DCMU and
DBMIB block electron transfer reactions, whereas
reduced paraquat autooxidizes to a radical,
resulting in the formation of superoxide and
other reactive oxygen species.
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Mechanism of cyclic electron transport in
chloroplasts
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The Calvin cycle is divided into three phases
carboxylation, reduction, and regeneration.
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Structure of Rubisco (L8S8)
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Rubisco activase removes bound RuBP from
inactive, decarbamylated Rubisco in an
ATP-dependent reaction.
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Micrograph showing Kranz anatomy in maize, a C4
plant. The closely spaced vascular bundles are
surrounded by large bundle sheath cells.
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General aspects of the C4 pathway
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Electron micrograph comparing the chloroplasts of
a bundle sheath cell (bottom) and a mesophyll
cell (top) in a C4 plant (sorghum).
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C4 pathway NADP-malic enzyme C4 photosynehesis
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C4 pathway NAD-malic enzyme C4 photosynehesis
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C4 pathway PEP carboxy-kinase C4 photosynthesis
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PEP carboxylase regulation in C4 plants. Light
activates a regulatory kinase by an as yet
unknown mechanism.
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Crassulacean acid metabolism (CAM) is an
evolutionary adaptation to photosynthesis in an
arid environment