cell powerpoint - 2012.pdf

7/27/2019 cell powerpoint - 2012.pdf

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CellUnit of life


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Discovery of Cell

Matthias Scleiden (1838)

Theodor Schwann (1839)

Robert Hooke (1665)

tiny compartments in cork

tissue (cells)

R. J. H. Dutrochet

( 1824)

Robert Brown (1833)


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Cells basic structural and

functional unit

Physical framework formetabolism

Diverse shapes, sizes,

and composition


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Cell Shape Dimension

Mitotic cells Cube 12m 3 12m 3 12m

Epidermal cell Flat, paving stone 45m 3 143m 3 15m

Photosynthetic cells of

pear

Short cylinder 7.4 m diam 3 55m

Water conducting

vessels in oak

Short cylinder 270 m diam 3 225m

Fiber cells in hemp Long cylinder 20 m diam 3 60,000m


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Two basic types of cells1. prokaryote

without nucleus and other membranebounded organelles.

e.g eubacteria and archaebacteria

2. Eukaryotecell with nucleus and membranebounded organelles.

e. g. protists, fungi, plants, animals.


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A plant cell consists of three general parts:

1. the cell wall

2. the protoplasm

3. the cell inclusion
http://micro.magnet.fsu.edu/cells/plants/plantmodel.html


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Cell wall Almost all plant cells have

a cell wall, except spermcells

Inert secretion

Provides strength andprotection

An active, dynamicorganelle

.


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Cell wall composition

Cellulose microfibril 10-25nm

Hemicelluloses bound together

the microfibrils

Middle lamella an adhesive layer(composed of pectic substances)

Primary wall and secondary wall

Secondary wall - impregnated with

lignin


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Association of Cells

1. secretion of signal molecules unicellular organisms

2. connections between cells- multicellular organims

Plasmodesmata- cytoplamicchannels

symplast interconnectedprotoplasm of all cells.

apoplast intercellularspaces and the cell wall

Permit rapid diffusion of gases

because plants do not have lungs.


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Cell membrane- osmoregulator, semi-permeable, phospholipid bilayer, fluid mosaic model.


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phospholipid bilayer

60% protein and 40% lipids

heterogenous fluid mosaic

Composition of membranes


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Properties of membranes

1. Dynamic and can grow

2. Transport materialsa. exocytosis

b. endocytosis


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Properties of membranes

3. Selective permeability1. diffusion2. osmosis

3. facilitated diffusion

4. active transport


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Diffusion


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Osmosis- movement of water across a semi-permeablemembrane following concentration gradient

Isotonic = equal

concentration of solute

Hypotonic- lesser

solute concentration

Hypertonic- greater

solute concentration


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Osmosis in plant cells

Normal plant cells in

isotonic solution

plant cells in hypotonic

solution

Turgidity

plant cells in

hypertonic solution

Plasmolysis


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Facilitated Diffusion


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Active Transport- transport of materials (ions, amino acids,etc)against concentration gradient.


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Nucleusarchive or permanent storage of organismsgenetic information

Onion cells with nucleus


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Chromatin complex of nuclear DNA + Histones


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Central vacuole tonoplastwater, starch, protein, granules or fibrous materials

Mit h d i


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Mitochondrion- respiratory site of the cells (ATP)

have their own DNA and ribosomes

circular mitochondrial DNA without histones

ribosomes resembles prokaryote

1 m in diameter by 5 m in length


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Plastidssynthesis, storage, export, formation ofcolors, synthesis of amino acids: isoleucine and valine

synthesis of aromatic rings : phenylalanine, tryptophan,

tyrosine

DNA without histones and circular DNA

Proplastids

plastids of young dividing cells

1. chloroplast

2. amyloplast

3. chromoplast


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Chloroplastmostly disc-shaped organelles, 4 to 6 m,capture light energy


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Leucoplastidscolorless plastids Amyloplast stores starch.

Aleuroneplast- stores protein

Elaioplast stores oils and fats.


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Chromoplast- fat-soluble pigments giving colors to fruitsand flowers


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Endoplasmic reticulum - network of narrow tubes andsheets of membranes that carries protein and secretes

lipids.


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Dictyosomes stack of thin vesicles held together in a flat orcurve array


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Ribosomes- non-membrane bounded organelles for proteinsynthesis


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Microbodies-small, spherical bodies 0.5m to 1.5m indiameter, single membrane

2 types:

1. peroxisomes- produces and degrades hydrogenperoxide (H2O2), detoxifies harmful products of

photosynthesis

2. glyoxysomes convert fats into sugars, importantin germination of fat-rich oily seeds.


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Microtubules

act as cytoskeleton

Motility of organelles and or whole cellsAlpha-tubulin and beta-tubulin


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Microfilaments


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Storage products

Starch

Lipids

Plant Crystals

1. calcium oxalate

2. calcium carbonate


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Styloid crystals

Rosette crystals


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Crystals (CaCO3)

cystolith


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Thank you..

Ross D. Vasquez

June 2012

cell powerpoint - 2012.pdf

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