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Cell biology(formerly cytology, from the Greek kytos,"container") is an academic discipline that studies cells

theirphysiological properties

their structure,

the organelles they contain

interactions with their environment,

theirlife cycle, division and death.

Cellbasic unit of life structurally and functionally.History:

a. Robert Hooke (1665)using his microscope discoverscells in cork

b. Schleiden ; Schwann and VirchowCell theory:

1. All organisms are composed of one or morecells

2. The cell is the structural unit of life3. Cells can arise only by division from

preexisting cells

http://en.wikipedia.org/wiki/Physiologyhttp://en.wikipedia.org/wiki/Organelleshttp://en.wikipedia.org/wiki/Cell_cyclehttp://en.wikipedia.org/wiki/Cell_divisionhttp://en.wikipedia.org/wiki/Apoptosishttp://en.wikipedia.org/wiki/Apoptosishttp://en.wikipedia.org/wiki/Cell_divisionhttp://en.wikipedia.org/wiki/Cell_cyclehttp://en.wikipedia.org/wiki/Organelleshttp://en.wikipedia.org/wiki/Physiology

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Fundamental properties shared by all cells: (conserved throughout evolution)

1. all cells employ DNA as their genetic material2. surrounded by plasma membrane3. use the same basic mechanisms for energy metabolism

Organisms:1. Unicellular (eg. bacteria, amoebas & yeasts) capable of independent

self-replication2. Multicellular(eg. Humans)- composed of collection of cells w/c fxns in

a coordinated manner w/ diff cells specialized to performparticular tasks.

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Two Main Classes of Cells:

a. Prokaryotic cells no nucleus- simpler structure (bacteria)

b. Eukaryotic cells - contain nucleus-more complex structure(protists, fungi,

plants & animals)

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Prokaryotes Eukaryotes

Typical organisms bacteria, archaea protists, fungi, plants, animals

Typical size ~ 1-10 m~ 10-100 m (sperm cells, apart from

the tail, are smaller)Type ofnucleus nucleoid region; no real nucleus real nucleus with double membrane

DNA circular (usually)linear molecules (chromosomes)with histoneproteins

RNA-/protein-synthesis coupled in cytoplasmRNA-synthesis inside the nucleusprotein synthesis in cytoplasm

Ribosomes 50S+30S 60S+40S

Cytoplasmatic structure very few structureshighly structured byendomembranes and a cytoskeleton

Cell movement flagella made offlagellinflagella and cilia containingmicrotubules; lamellipodia andfilopodia containing actin

Mitochondria noneone to several thousand (though

some lack mitochondria)Chloroplasts none in algae and plants

Organization usually single cellssingle cells, colonies, highermulticellular organisms withspecialized cells

Cell division Binary fission (simple division)Mitosis (fission or budding)Meiosis

DNA content (base pairs) 1 106 to 5 106 1.5 107 to 5 109

Table 1: Comparison of features of prokaryotic and eukaryotic cells

http://en.wikipedia.org/wiki/Bacteriumhttp://en.wikipedia.org/wiki/Archaeahttp://en.wikipedia.org/wiki/Protisthttp://en.wikipedia.org/wiki/Fungushttp://en.wikipedia.org/wiki/Planthttp://en.wikipedia.org/wiki/Animalhttp://en.wikipedia.org/wiki/%CE%9Cmhttp://en.wikipedia.org/wiki/%CE%9Cmhttp://en.wikipedia.org/wiki/Spermatozoonhttp://en.wikipedia.org/wiki/Cell_nucleushttp://en.wikipedia.org/wiki/Nucleoid_regionhttp://en.wikipedia.org/wiki/Chromosomehttp://en.wikipedia.org/wiki/Histonehttp://en.wikipedia.org/wiki/Proteinhttp://en.wikipedia.org/wiki/Cytoplasmhttp://en.wikipedia.org/wiki/Ribosomehttp://en.wikipedia.org/wiki/Cytoskeletonhttp://en.wikipedia.org/wiki/Chemotaxishttp://en.wikipedia.org/wiki/Flagellumhttp://en.wikipedia.org/wiki/Flagellinhttp://en.wikipedia.org/wiki/Ciliumhttp://en.wikipedia.org/wiki/Microtubulehttp://en.wikipedia.org/wiki/Lamellipodiahttp://en.wikipedia.org/wiki/Filopodiahttp://en.wikipedia.org/wiki/Actinhttp://en.wikipedia.org/wiki/Mitochondriumhttp://en.wikipedia.org/wiki/Chloroplasthttp://en.wikipedia.org/wiki/Algaehttp://en.wikipedia.org/wiki/Planthttp://en.wikipedia.org/wiki/Cell_divisionhttp://en.wikipedia.org/wiki/Binary_fissionhttp://en.wikipedia.org/wiki/Mitosishttp://en.wikipedia.org/wiki/Meiosishttp://en.wikipedia.org/wiki/Meiosishttp://en.wikipedia.org/wiki/Mitosishttp://en.wikipedia.org/wiki/Binary_fissionhttp://en.wikipedia.org/wiki/Cell_divisionhttp://en.wikipedia.org/wiki/Cell_divisionhttp://en.wikipedia.org/wiki/Planthttp://en.wikipedia.org/wiki/Algaehttp://en.wikipedia.org/wiki/Chloroplasthttp://en.wikipedia.org/wiki/Mitochondriumhttp://en.wikipedia.org/wiki/Actinhttp://en.wikipedia.org/wiki/Filopodiahttp://en.wikipedia.org/wiki/Lamellipodiahttp://en.wikipedia.org/wiki/Microtubulehttp://en.wikipedia.org/wiki/Ciliumhttp://en.wikipedia.org/wiki/Flagellinhttp://en.wikipedia.org/wiki/Flagellumhttp://en.wikipedia.org/wiki/Chemotaxishttp://en.wikipedia.org/wiki/Cytoskeletonhttp://en.wikipedia.org/wiki/Ribosomehttp://en.wikipedia.org/wiki/Cytoplasmhttp://en.wikipedia.org/wiki/Proteinhttp://en.wikipedia.org/wiki/Histonehttp://en.wikipedia.org/wiki/Chromosomehttp://en.wikipedia.org/wiki/Nucleoid_regionhttp://en.wikipedia.org/wiki/Nucleoid_regionhttp://en.wikipedia.org/wiki/Nucleoid_regionhttp://en.wikipedia.org/wiki/Cell_nucleushttp://en.wikipedia.org/wiki/Spermatozoonhttp://en.wikipedia.org/wiki/%CE%9Cmhttp://en.wikipedia.org/wiki/%CE%9Cmhttp://en.wikipedia.org/wiki/Animalhttp://en.wikipedia.org/wiki/Planthttp://en.wikipedia.org/wiki/Fungushttp://en.wikipedia.org/wiki/Protisthttp://en.wikipedia.org/wiki/Archaeahttp://en.wikipedia.org/wiki/Bacterium

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Fig.1.1.Average_prokaryote_cell-_en.svg (SVG

file, nominally 494 402 pixels, file size: 135KB)

http://upload.wikimedia.org/wikipedia/commons/5/5a/Average_prokaryote_cell-_en.svghttp://upload.wikimedia.org/wikipedia/commons/5/5a/Average_prokaryote_cell-_en.svghttp://upload.wikimedia.org/wikipedia/commons/5/5a/Average_prokaryote_cell-_en.svghttp://upload.wikimedia.org/wikipedia/commons/5/5a/Average_prokaryote_cell-_en.svg

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Fig1.2.Diagram of a typical animal (eukaryotic) cell, showing subcellular components.Organelles:(1) nucleolus(2) nucleus

(3) ribosome(4)vesicle(5) rough endoplasmic reticulum (ER)(6) Golgi apparatus(7) Cytoskeleton(8) smooth endoplasmic reticulum(9) mitochondria(10)vacuole(11) cytoplasm

(12) lysosome(13) centrioles within centrosome

http://en.wikipedia.org/wiki/Animaliahttp://en.wikipedia.org/wiki/Eukaryotichttp://en.wikipedia.org/wiki/Organellehttp://en.wikipedia.org/wiki/Nucleolushttp://en.wikipedia.org/wiki/Cell_nucleushttp://en.wikipedia.org/wiki/Ribosomehttp://en.wikipedia.org/wiki/Vesicle_(biology)http://en.wikipedia.org/wiki/Rough_endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Golgi_apparatushttp://en.wikipedia.org/wiki/Cytoskeletonhttp://en.wikipedia.org/wiki/Smooth_endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Mitochondrionhttp://en.wikipedia.org/wiki/Vacuolehttp://en.wikipedia.org/wiki/Cytoplasmhttp://en.wikipedia.org/wiki/Lysosomehttp://en.wikipedia.org/wiki/Centriolehttp://en.wikipedia.org/wiki/Centrosomehttp://en.wikipedia.org/wiki/Centrosomehttp://en.wikipedia.org/wiki/Centriolehttp://en.wikipedia.org/wiki/Lysosomehttp://en.wikipedia.org/wiki/Cytoplasmhttp://en.wikipedia.org/wiki/Vacuolehttp://en.wikipedia.org/wiki/Mitochondrionhttp://en.wikipedia.org/wiki/Smooth_endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Cytoskeletonhttp://en.wikipedia.org/wiki/Golgi_apparatushttp://en.wikipedia.org/wiki/Rough_endoplasmic_reticulumhttp://en.wikipedia.org/wiki/Vesicle_(biology)http://en.wikipedia.org/wiki/Ribosomehttp://en.wikipedia.org/wiki/Cell_nucleushttp://en.wikipedia.org/wiki/Nucleolushttp://en.wikipedia.org/wiki/Organellehttp://en.wikipedia.org/wiki/Eukaryotichttp://en.wikipedia.org/wiki/Animalia

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Fig.1.3.Diagram of a typical plant cell

http://micro.magnet.fsu.edu/cells/plantcell.html

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the First Cell:

-all present day cells (both prokaryotes & eukaryotes) descended

from a single ancestor. The 1st

cell is thought to have arisen at least 3.8 Byears ago as a result of enclosure of self-replicating RNA in a phospholipidmembrane (RNA world hypothesis)

Present-Day Prokaryotes-divided into two groups: the archaebacteria and the eubacteria which

diverged early in evolution

Eukaryotic Cells-thought to have evolved from symbiotic associations of

prokaryotes (ENDOSYMBIOSIS)

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ENDOSYMBIOSIS

A large anaerobic, heterotrophic prokaryote engulfs a small aerobic prokaryote

The aerobic endosymbiont has evolved into a mitochondrion

A portion of the plasma membrane has invaginated and evolved into anuclear envelope and endoplasmic reticulum

(primitive eukaryote)

Nonphotosynthetic protist, fungal,animal cells

Engulfs a photosynthetic prokaryote

Evolve into a chloroplast

Algal & plant cells

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Fig.1.4. Time scale of evolution The scale indicates the approximate times at which

some of the major events in the evolution of cells are thought to have occurred.

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Figure 1.5. Generation of metabolic energy Glycolysis is the anaerobic breakdown of glucose to lactic acid.

Photosynthesis utilizes energy from sunlight to drive the synthesis of glucose from CO2

and H2O, with the release

of O2

as a by-product. The O2

released by photosynthesis is used in oxidative metabolism, in which glucose is

broken down to CO2 and H2O, releasing much more energy than is obtained from glycolysis.

The Evolution of Metabolism:

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Figure 1.6. Evolution of cells Present-day cells evolved from a common prokaryotic ancestor along three

lines of descent, giving rise to archaebacteria, eubacteria, and eukaryotes. Mitochondria and chloroplasts

originated from the endosymbiotic association of aerobic bacteria and cyanobacteria, respectively, withthe ancestors of eukaryotes.

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Development of Multicellular Organisms

Plants

3 main tissue systems:1. ground tissue2. dermal tissue3. vascular system

Animals- cells are more diverse than those of plants- 5 main types of tissues

1. epithelial2. connective3. blood

4. nervous5. muscle

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Organism Haploid DNA content (millions of base

pairs)

Bacteria

Mycoplasma 0.6

E. coli 4.6

Unicellular eukaryotesSaccharomyces cerevisiae (yeast) 12

Dictyostelium discoideum 70

Euglena 3000

Plants

Arabidopsis thaliana 130

Zea mays (corn) 5000

Animals

Caenorhabditis elegans (nematode) 97

Drosophila melanogaster(fruit fly) 180

Chicken 1200

Zebrafish 1700

Mouse 3000

Human 3000

Table 1.2 DNA Content of Cells

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Cells as Experimental Models

E. coli S. cerevisiae Dictyostelium discoideum

Arabidopsis thaliana Caenorhabditis elegans Drosophila melanogaster

http://en.wikipedia.org/wiki/File:Adult_Caenorhabditis_elegans.jpghttp://en.wikipedia.org/wiki/File:Arabidopsis_thaliana.jpghttp://upload.wikimedia.org/wikipedia/commons/c/cf/Dictyostelium_Fruiting_Bodies.JPGhttp://upload.wikimedia.org/wikipedia/commons/d/d9/S_cerevisiae_under_DIC_microscopy.jpghttp://www.sciencedaily.com/images/2008/01/080106202952-large.jpg

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Xenopus laevis zebrafish

House mouse

http://en.wikipedia.org/wiki/File:House_mouse.jpghttp://en.wikipedia.org/wiki/File:Zebrafisch.jpg

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Tools of Cell Biology

1. Light Microscopy

Bright-field microscopy Phase-contrast microscopy Differential interference contrast microscopy Video-enhanced differential interference-contrast microscopy Fluorescence microscopy Confocal microscopy

Two-photon excitation microscopy

2. Electron microscopy Transmission electron microscopy Scanning electron microscopy

Several different techniques exist to study cells:1. Cell culture 6. In situ hybridization2. Immunostaining 7. PCR3. Computational Genomics 8. Cell Fractionation4. DNA MICROARRAYS

5. Gene knockdown

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a. Differential-interference-contrastmicrograph of a mitotic yeast cell.

b. Fluorescence microscopy

c. Phase-contrast micrograph of fibroblasts inculture.

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Scanning electron micrographof a flea

Transmission electron micrographofBacillus anthracis

http://www.imageenvision.com/md/stock_photography/bacillus_anthracis_transmission_electron_micrograph.jpghttp://www.google.com.ph/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/6/66/Scanning_Electron_Micrograph_of_a_Flea.jpg&imgrefurl=http://commons.wikimedia.org/wiki/File:Scanning_Electron_Micrograph_of_a_Flea.jpg&h=499&w=387&sz=40&tbnid=mRcDo42VlRKDMM:&tbnh=130&tbnw=101&prev=/images?q=scanning+electron+micrograph&hl=en&usg=__6YcHJXQ25jFYRRnBAKkbqXiSBQY=&ei=hIU7SvvgK8aUkAXE7tSsDg&sa=X&oi=image_result&resnum=1&ct=image

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Figure 1-7. A procedure used to make a transgenic plant.

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http://en.wikipedia.org/wiki/File:PCR_tubes.pnghttp://www.molecularstation.com/molecular-biology-images/506-molecular-biology-pictures/23-pcr-machine-pcr-thermocycler.html

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Figure 1.8. Using DNA microarrays to monitor theexpression of thousands of genes simultaneously.

Figure 8-63. Using cluster analysis toidentify sets of genes that are coordinatelyregulated.

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Figure 8-47. Results of a BLAST search. Sequence databases can be

searched to find similar amino acid or nucleic acid sequences. Here a

search for proteins similar to the human cell-cycle regulatory protein

cdc2 (Query) locates maize cdc2 (Subject), which is 68% identical (and

82% similar) to human cdc2 in its amino acid sequence.