Chapter 1

Primary producers Nonmotile Structurally reinforced to grow against

gravity Mechanisms for moving water, mineral

nutrients, and photosynthate Mechanisms for avoiding dessication

against transpiration

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Seed Plants similar Seed plants ??? Vegetative

Photosynthesis Support Anchorage & absorption

Reproductive

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1° growth – new organs and basic plant form Division followed by enlargement producing axial

polarity 2° growth – radial polarity Limited to meristems

Apical Lateral Pericycle – internal meristem

Differentiation after elongation

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3 major systems ….

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Rigid cell wall Middle Lamella ∴ Development depends on

patterns of division and enlargement 1° -- young & thin 2° -- stronger; thicker

Lignin Pits & pit pairs

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Your basic eukaryotic cell Endomembrane system

Includes vacuole, endosomes Secretory processes, membrane recycling and cell cycle

Independently dividing organelles derived from endomembrane system

Oil bodies (oleosomes), peroxisomes, glyoxysomes Independently dividing, semiautonomous

organelles Plastids & mitochondria

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Phospholipid bilayer Chloroplasts glycosylglycerides

No phosphate! Head group

Serine Choline Glycerol Inositol

Amphipathic

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Higher percentages of unsaturated fatty acids Oleic acid (1 double bond) Linoleic acid (2 double bonds) Linolenic acid (3 double bonds)

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Integral Peripheral Anchored Transient aggregates lipid rafts

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Integral -- spans entire width Ion channels Signal transduction pathways Some also bind to cell wall

Peripheral – bound to membrane surface by non-covalent bonds Bonds broken with high-salt or chaotropic agents Interactions between membrane and cytoskeleton

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Anchored – bound via covalently attached lipid molecules Fatty acid and prenyl groups on the cytoplasm

side Glycosyl-phosphatidylinositol-anchors (GPI) on

the outside leaflet

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Divide the cell into structural/functional compartments

Distribute membranes and proteins via vesicles

Protein synthesis (some)

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Nuclear genome Sizes from 1.2 x 108 (Arabidopsis thaliana) to 1.5

x 1011 (Kinugasa japonica … largest known genome!) base pairs

Nuclear membrane – subdomain of ER Nuclear pores – connect nucleoplasm with

cytoplasm 100+ nucleoporin proteins in complexes

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Chromosomes Chromatin

Heterochromatin – transcriptionally inactive & highly compact

Euchromatin – transcriptionally active and dispersed

Nucleolus Ribosome synthesis Nuclear ribosomes larger

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Clearly I need a new Cell Biology book …… Rough vs smooth

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Inherent sided-ness Laid down in ER

Enzymes that synthesize photsholipeds Phospholipids different (cytosolic vs lumenal

sides) Lumenal side – which side of Plasma Membrane?

Flippases – counteract membrane sidedness ER & plastids synthesize new membrane Other organelles – fusion & fission

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Seccretory pathway ER to Golgi to plasma membrane and cells exterior

Cotranslational insertion SRP binds and interrupts translation Protein structure (SRP+ribosome) causes

docking with translocon and translation resumes

http://en.wikipedia.org/wiki/File:Protein_translation.gif

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(aka dictyosome) Polarized stack (i.e., sided!) – cis/trans

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Text -> Vesicular Transport Evidence -> Cisternal maturation http://www.nature.com/scitable/topicpage/how-do-proteins-move-thro

ugh-the-golgi-14397318

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(left) Cisternal maturation; (right) Vesicular Transport

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COP II proteins ER to Golgi COP I proteins Golgi to ER

Also trans-face to cis-face Called retrograde movement replenishes

Golgi membranes Clathrin

endocytosis

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Tonoplast Vesicular sap

Protein bodies Secondary metabolites Lytic vacuoles

Not all vacuoles are derives from Golgi!

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Oil bodies Microbodies

Peroxisomes & glyoxisomes

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Mitochondria Chloroplasts and other plastids

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Chloroplasts Chromoplasts carotenoids Leucoplasts – non-pigmented

Amyloplast – starch

Protoplastids Etioplasts (see web topic 7.11)

Division independent of the nucleus!

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Microtubules and Microfilaments ONLY Microtubules – tubulin dimers Microfilaments – G-actin subunits

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Monomers contain bound nucleotide Actin – ATP Tubulin – GTP

Both polarized - tubulin monomer exposed on minus endα - tubulin monomer exposed on plus endβ

Proteins prevent depolymerization (for details watch the Harvard video!

http://multimedia.mcb.harvard.edu/

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Microtubules can “treadmill” throughout the cell! Orientation of microtubules determines

orientation of expansion in the cell wall

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Motor proteins -- http://www.youtube.com/watch?v=lLxlBB9ZBj4

Myosins – move along microfilaments (towards the plus end) 2 families

Kinesins – microtubules 61 members 2/3 towards plus end Also bind to chromatin and other

microtubules Dyenins (- mvmt) absent in plants

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G1 – pre DNA for replication Pre-replication complex at origins of replication

S – replicate DNA G2 – prepare for mitosis

Mitosis – previously replicated chromosomes are aligned, separated and distributed in an orderly fashion to daughter cells

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Process highly conserved Regulated by cyclins and cyclin-dependant protein

kinases (Cdks) Kinases enzymes that phosphorylate proteins using

ATP Three cyclins (A, B, and D) Cdk activity regulated either by

Cyclin systhesis/degredation Cdk inactive unless associated with a cyclin

Phosphorylation/dephosphorylation of AA residues within Cdk

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Note: Interphase broken out!

G1, S, and G2 – traditional definitions

Cyclin D and Cdk A – transition from G1 to S

Cyclin A and Cdk A transition from S to G2

Cyclin B and Cdk B transition from G2 to M

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Entire cell structure altered Single central vacuole is split by cytoplasmic

transvacuolar strands – where nuclear division will occur

Organelles partition themselves Cohesins hold sister chromatids together

Plant cells can leave the cell cycle endoreduplication

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Pre-prophase band Ring of microtubules Precursor to cell wall plate Same place cytoplasmic transvacuolar strands were

No centrioles/

centrosomes

Red– microtubules; green– nuclear

envelope; blue -- DNA

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Nuclear membrane re-assimilated into the ER! Nucleolus fragments Spindle assembly checkpoints

Cyclin B-Cdk B complex Transition to Anaphase after

all chromosomes positioned QUICK -- http://www.youtube.com/watch?v=aDAw2Zg4IgE

Red– microtubules; green– nuclear

envelope; blue – DNA. Fig 3: green—

ER

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Anaphase – 2 “components” Chromatids pulled toward poles Poles pushed apart Book says can’t be pulled b/c no centrioles??

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Phragmoplast – microtubules, ER, vesicles Vesicles contain the middle lamella

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Mitotic spindle -> phragmoplast Orients vesicles from Golgi

apparatus. Vesicles fuse to form cell

plate Vesicles contain middle

lamella Cytokinesis complete --

cellulose synthase complex inserted into new membranes

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Cellulose synthase. Synthesizes the chains Assembles them into

microfibrils Extrudes from plasma

membrane into cell wall Cellulose -- synthesized

from uridine diphosphiglucose

Details poorly known

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Cell plate formation – incomplete membrane fusion Plasmodesmata -- Cytoplasmic

continuity between daughter cells Desmotubule -- ER

Symplast – continuous cytoplasmic network throughout plant Allows for exchange of molecules

between cells without crossing membranes.

Apoplast – continuous extracellular/non-cytoplasmic space

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Tubular extensions of the plasma membrane

Connect cytoplasm of adjacent cells – symplast Allows water and

solutes to cross

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