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9/8/11
1
â˘â1- How would you describe a cell?
â˘â2- What are parts of a cell or organelles you remember from previous classes?
Cell Theory â˘â 1- All living things . â˘â 2- Cells are . â˘â 3- Cells come from .
So many different kinds of cells!
â˘â Size â˘â Shape â˘âOrganization
Cell Size
Head of a pin = 2 mm Human hair = 200 Âľm Plant cell = 100 Âľm Animal cell = 10 Âľm
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Cell shape â˘â Significant variation
in cell shape among species and within the same organisms
â˘â Shape is tied directly to function
Cell organization
â˘âDifferences in organization can occur at the level of the cell or at the level of a tissue
â˘â At the cellular level: ââWhat kinds of organelles? ââWhat kind of cytoskeletal organization?
â˘â At the tissue level: ââHow are the cell organized relative to each
other?
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Variability in cell function â˘â Protection (Epidermis) â˘âCommunication (Nervous system) â˘âReproduction (Reproductive system) â˘â Keeping us healthy (Immune system) â˘âChemical exchange (Cardiovascular
system, Respiratory system)
Cell Chemistry â˘â Even with all this variability, cells still have
basic chemistry in common ââGenetic material (RNA, DNA)
â˘âNucleotides
ââProteins â˘âAmino acids
â˘âCells use this genetic information and proteins to reproduce independently
Eukaryotes and Prokaryotes
â˘â Eukaryotes â˘â Prokaryotes
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Prokaryotes â˘â Incredibly diverse group of cells! â˘âNo nucleus â˘â Size: tend to be smaller than eukaryotes â˘â Shape: spherical, rodlike, corkscrew â˘â Tough protective coat (cell wall) â˘âRapid growth rate
Bacteria vs. Archaea Bacteria â˘â Single celled â˘â Cell wall â˘â Circular DNA â˘â No nuclear membrane â˘â E. coli, salmonella,
anthrax
Archaea â˘â Simple organisms without
a nuclear membrane â˘â Replicate their DNA and
protein differently than bacteria
â˘â Extreme conditions
Some interesting prokaryotes
Bacteria - Photoautotrophs
Bacteria - Chemoautotrophs
Archaea- Methanogens
Archaea- Thermophiles
Eukaryotes
â˘â Typically bigger than prokaryotes â˘â Have nucleus and membrane-bound organelles
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Figure 1-29 Essential Cell Biology (Š Garland Science 2010)
The cell membrane â˘â Function
ââBarrier to outside world ââRegulates movement of molecules from the
outside of the cell to the inside ââSignaling (lipid rafts)
â˘â Key components ââPhospholipids ââIntegral membrane proteins (all the way through) ââPeripheral membrane proteins
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Phospholipids
â˘â Form bilayer â˘âHead group = POLAR â˘âHydrocarbon tails =
NONPOLAR â˘âMost things that want
to get through need an escort
Cytoplasm
â˘âCellular material that lies between the cell membrane and the nucleus
â˘â LOTS of fun stuff happens here! ââSite of RNA processing on free ribosomes ââHouses all the organelles
The nucleus â˘â Function
ââContains cellular DNA ââSite of transcription (DNA to RNA)
â˘â Key components ââNucleolus ââNuclear envelope ââNuclear pores (regulate transport into and out
of nucleus) ââChromatin (DNA + histone proteins)
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Figure 1-22 Essential Cell Biology (Š Garland Science 2010)