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Flashcards in PLANT CELL Deck (92):
1

CELL WALL (PRIMARY CELL WALL)

A strong, lattice-like structure, averaging 20 nm thick, with the primary function of containing and protecting the pertinences of the cell.

Mostly made up of cellulose, the cell wall is extremely porous, as that of a luffa.

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1.) LIGNIN

2.) SUBERIN





Endodermis

1.) Long chained carbon molecule and the major component of wood.

2.) A waxy, waterproof substance synthesized within the cell and usually found in the secondary cell wall.
It is also found in the endodermis for woody and herbaceous plants.

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SECONDARY CELL WALL

Present in woody plants, is a lignin based layer that sometimes sits up against the primary cell wall and usually contains suberin.

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ENDODERMIS

A special set of cells located in the interior of roots protecting and separating the vascular cambium from the epidermis and cortex.

Also, roughly considered the dividing point between apoplastic and symplastic pathways for H20.

Found in woody and herbaceous plants; cells in the endodermis have a strips of suberin that forms and H20 barrier.

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CASPARIAN STRIP







plasmalemma

The clogged portion of waxy cell walls in the endodermis preventing water from flowing any further into the root unless it meets the screening criteria for the next layer of the cell; the plasmalemma.

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PLASMALEMMA






Phospholipid
Osmosis and diffusion

Semi-permeable outer cell membrane that sits against the inside of the cell wall.

An oil/gelatin (plasma-like) barrier, made up of two phospholipid layers.

Composed of protein and carbohydrate chains, with negatively charged heads (hydrophillic), and neutral charged tales (hydrophobic).

Think peanut butter jelly sandwhich.

Diffusion for larger molecules such as C02 and N02.

Osmosis for H20 + smaller molecules that can enter in dissolved states.

It is important that the plasmalemma screen out what should not be entering.

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PLASMODESMATA
PLASMODESMA (singular)





Symplastic
Endoplasmic reticulum

The area inside a cell membrane that is connected to the inside of adjacent cells through the symplastic pathway; is made possible by the presence of tunnels called plasmodesmata.

About 50nm in diameter and 90-100nm long. (H20 molecule = 1nm) Each has smaller tubular connections to the Endoplasmic Reticulum.

At each end of these tunnels are sphincter acting proteins, responsible for regulating what molecules are allowed through.

Cellular Screen Window.

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AQUAPORINS






Direct pathway
Cellular turgidity

Special proteins embedded in the plasmalemma that only transport water molecules across the phospholipid membrane. (Direct Pathway).

One H20 molecule at a time.

Covers as much as 10% of the plasmalemma surface area.

Working with the plasmalemma and plasmodesmata to control cell turgidity.

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INTEGRAL MEMBRANE PROTEINS (IMP's)

1.) Channel Proteins
2.)Pump Proteins
3.)Co-transporters

Are the entryways for plant nutrients and exit-ways for for exudates/metabolites.

Make up 50-75% of the plasmalemma surface.

A molecule must be charged in order to pass through the IMP (almost always ionic with the exception of Boron).

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CHANNEL PROTEINS (a.k.a gated channels)






Passive transport

Serve as passive transport tunnels (channel=open, gate=open or closed) sometimes with gate mechanisms at either end, regulating the flow of molecules through a change in size or shape.

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PUMP PROTEINS (a.k.a transport proteins)




Active transport
hydrogen ions
Sodium and potassium pumps

Serve as active transport miniature pumps.

The most prevalent kind, move positively charged hydrogen ions (H+) out of the membrane onto the outer surface of the plasmalemma; where they can then be used by other molecules for cell entrance.

Sodium and potassium pumps are also present.

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CO–TRANSPORTER PROTEINS (a.k.a. carrier proteins)





Facilitative transport

These proteins bind to molecules and are then moved across the membrane through facilitative transport.

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CYTOPLASM







Cytosol

All the stuff inside of the cell membrane, except for the nucleus.

Consists mostly of cytosol (clear, jelly like fluid), holding the organelles and vesicles in place.

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MITOCHONDRIA





Cellular respiration.
ADP and ATP
Cristae

Cylindrical oganelles that produce energy for the cell, through respiration (ADP-->ATP), from the sugars produced during photosynthesis.

Bound through a double layer Phospholipid membrane complete with transport proteins. The inner membrane is folded over itself(to increase surface area and reaction sites) like ribbon candy, producing numerous attached compartments called cristae.

This is where the respiration reaction takes place.

Also synthesize phospholipids for the cellular membrane. Help to store calcium used in intercellular signaling of the symplastic pathway.

Scientist believe that mitochondria were once free living bacteria though somehow, either through endocytosis or some sort of symbiotic relationship, became incorporated into the plant cell.

Mitochondria account for up to 20% of a cells total volume.

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PLASTIDS

1.)Chloroplasts
2.)Leucoplasts
3.)Chromoplasts

Mini-factory and storage facilities

1.) Sites where photosynthesis takes place. Filled with chlorophyll.

2.)Colorless cells located in parts of plants not exposed to light; used primarily for storage of lipids and proteins.

3.) Cells that contain the red, yellow, and orange pigment found in flowers, fruits, and some roots.

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CHLOROPLASTS





Photosynthesis
Thylakoid discs
Grana (Granum)

Also contain a double layered phospholipid membrane, with the inside layer containing numerous folds to add surface area for the photosynthetic reaction to occur.

Inside each chloroplast are thylakoids, membrane-bound structures that are flattened, hollow discs, stacked (grana) one on top of another. This is where the chlorophyll pigments convert sunlight into energy.

The area between the membrane and the grana is called the stroma.

There are about half a million chloroplasts in a square millimeter of a leaf (40-50chloroplasts/plant cell).

Similar to mitochondria, scientists postulate that originally chloroplasts were separate bacteria that became incorporated into the cell.

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RIBOSOMES





mRNA
tRNA
Golgi apparatus

Bead shaped organelles (smallest) that serve as the sites of protein synthesis: therefore take up most energy in the cell.

Constructed in the nucleus and then carried out into the cytoplasm. Either free floating in the cytoplasm (proteins within the cell) or attached to the Endoplasmic Reticulum (proteins to be exported out of the cell).

MessengerRNA (mRNA) delivers sequences of a particular protein to the ribosome to be copied. TransferRNA (tRNA) then brings one of 20 amino acids to the ribosome to create the correct protein chain.

These chains are then sent to the Golgi Apparatus for final processing.

They have a negative charge and have no phospholipid membrane.

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ENDOPLASMIC RETICULUM (ER)
rough/smooth


Nucleus
Lumen Cavities
Nucleotides
Vesicles
Glycoproteins

A long membrane folded over itself again and again to create a maze of cavities known as the lumen.
In contact with the nucleus the ER extends all the way to the plasmalemma.

Section of the ER with ribosomes studded all over, is referred to as the rough ER as opposed to the smooth ER without ribosomes.

It is from the smooth ER that protein chains are transported out of or to other parts of the cell. Also here that, nucleotides are attached to the ends of these chains to serve as the address codes for delivery. Additionally lipids are made in the smooth ER.

Sugar are also added to proteins in the ER, to make glycoproteins, necessary for cellular transactions.

The ER converts toxic materials into benign substances to be transported out of the cell or into the vacuole using vesicles.

The ER provides an easier path for molecules to travel through the cell as opposed to slogging through cytosol.

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GOLGI APPARATUS







Cisterna sacs (cisternae)

Composed of stacked, enclosed membranes containing enzymes that modify the materials sent to the complex. There are about 5 to 8 golgi apparatuses/plant cell, and each one contains a separate set of enzymes.

Are the packing and shipping centers within a cell, and are connected to the endoplasmic reticulum through actin filaments and micro tubules.

Once inside the Golgi bodies, molecules go through a series of long passages where they can be completed, sorted, chemically tagged with a destination code, and loaded into a cisternae to be mounted onto vesicles for final transport (which can be inside or outside of the cell.)

Materials include polysaccharides for making cellulose, root exudates, and proteins in general.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

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VESICLES

Membrane bound structures that transport materials inside the cell.

86

VACUOLE

A single membrane organelle filled with cell sap, a watery mixture of molecular compounds containing cytosol sugars, enzymes, proteins, organic acids, and pigment molecules.

Young plant cells may have several vacuole vesicles that can merge together; older cells only have one.

A single vacuole can take up as much as 90% of the cell volume.

Turgor pressure: as the vacuole feels accordingly it expands and increases the pressure within the cell.

Plasmolysis: when there is a shortage of water in the vacuole, the plasmalemma shrinks away from the cell wall, and causes wilting.

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TONOPLAST

The vacuoles membrane.

Transport of materials across the tonoplast most often requires the input of energy (active transport).

The tonoplast keeps the pH in the cytosol at the proper level by pumping or excreting hydrogen ions into the vacuole. The ideal pH is around neutral at 7.

In some instances part of the tonoplast can merge with the plasmalemma to export wastes gathered in the vacuole out of the cell.

When the tonoplast no longer functions; wastes are no longer contained, turgor is affected, cytosol pH is altered, and ultimately cellular death ensues.

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LYSOSOMES

Are single layered membrane bound organelles that serve as the cells recycling centers and are formed when part of the Golgi Apparatus membrane buds off, containing enzymes that digest large molecules (mostly proteins) into smaller components.

The number of lysosomes varies but can range up to 100.

Lysosomes require an acidic pH around 5 and won't work at higher levels.

At the end of the cells life, without cellular function, the environment becomes acidic enough so that the enzymes working within the lysosome are released in order to digest the dead cell.

The recycling stream includes bacteria, nutrient molecules, proteins, lipids, polysaccharides, nucleic acid's, and even of organelles that no longer function such as ribosomes or spent mitochondrion.

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PEROXISOMES

Similar to lysosomes, also serve as digestion vessels in the cytosol however are specialized in the digestion of lipids and fats.

Peroxisomes are generated from the proteins and lipids made in the endoplasmic reticulum.

They can also help in the cellular assimilation of nitrogen and the metabolism of hormones.

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Microtubules

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NUCLEUS

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Actin-Flilaments

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