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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
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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.