miércoles, 12 de agosto de 2009


1665- Robert Hooke employed “CELL” concept for the first time.
1824- René Dutrochet extended cellular concept to structural unit.
1838 Mathias Schleiden (plants) and Theodor Schwann (animals) proposed that all living things are made of cells.
1858, Rudolf Virchow established that all cells come from others cells (axioma "ommni cellula e cellula").

§ The cell is the smallest structural and functional unit capable of carrying out life processes.
§ Cells are the living building blocks of all plant and animal organisms.
§ The functional activities of each cell depend on the specific structural properties of the cell.
§ All organism’s structure and function ultimately depend on the capabilities of its cells.
§ All new cells and new life arise only from pre-existing cells.
§ Because of this continuity of life, the cells of all organisms are fundamentally similar in structure and function.

Characteristics of All Cells
• A surrounding membrane
• Cytoplasm – cell contents in thick fluid
• Control center with DNA

Eukaryotic Cells
First cell type on earth
Kingdoms: Eubacteria and Archaeabacteria
No membrane bound nucleus
Nucleoid = region of DNA concentration
Organelles not bound by membranes
VERY small
Nucleus bound by membrane
Kingdom: fungi, protists, plant, and animal cells
Possess many organelles (structures Bound by

Mitochondrion: An important cell organelle involved in respiration.
Cytoplasm: A fluid surrounding the contents of a cell and forms a vacuole.
Golgi Apparatus: The processing area for the creation of a glycoprotein.
Endoplasmic Reticulum: An important organelle heavily involved in protein synthesis.
Vesicles: Packages of substances that are to be used in the cell or secreted by it.
Nucleus: The "brain" of a cell containing genetic information that determines every natural process within an organism.
Cell Membrane: Also known as a plasma membrane, this outer layer of a cell assists in the movement of molecules in and out the cell plays both a structural and protective role.
Lysosomes: Membranous sacs that contain digestive enzymes.
Cell Wall: A structure that characteristically is found in plants and prokaryotes and not animals that plays a structural and protective role.

In and Out - getting things into and out of cells

Active Transport - Active transport is the transport of molecules with the active assistance of a carrier that can transport the material against a natural concentration gradient.
Passive Transport (Diffusion) - The movement of molecules from areas of high concentration (i.e. outside a cell) to areas of low concentration (i.e. within a cell) via a carrier. This process does not require energy.
Simple Diffusion - The movement of molecules from areas of high concentration to areas of low concentration in a free state. Osmosis of water involves this type of diffusion through a selectively permeable membrane (i.e. plasma membrane).

The Breakdown of Materials in a Cell

In cells, sometimes it is required to breakdown more complex molecules into more simple molecules, which can then be 're-built' into what is needed by the body with these new raw materials.

'Pinocytosis' where to contents of a structure (such as bacteria) are drank, essentially by breaking down molecules into a drinkable form.

'Phagocytosis' where contents are 'eaten'. See cell defence for more information in regards to this.

Absorption and Secretion
Absorption is the uptake of materials from a cells' external environment. Secretion is the ejection of material.


Cells are too small to see by the naked eye
Antony van Leeuwenhoek (1632-1723) - developed some of the earliest microscopes
Modern Microscopes
Bright Field, Fluorescence, Phase Contrast, Dark Field, Differential Interference, Digital Video Microscopy, Confocal, 2 photon confocal, spinning disc confocal, total internal reflection fluorescence (TIRF),
Electron Microscope (EM)
Transmission, scanning, scanning tunneling
Magnetic Resonance Imaging (MRI)

Modern Cell Biology

Arose from 3 separate fields becoming interwoven over the last 50 years

Oldest branch
Dependent on optical techniques
1870 invention of microtome for sectioning biological specimens
Light Microscope
1828 Freidrich Wohler showed urea synthesis from ammonium and cyanate (organic compounds synthesized from inorganic compounds)
biological chemistry (biochemistry) the same as all other chemistry
1868 Louis Pasteur shows yeast cells needed for fermentation of sugar into alcohol (living organisms for specific chemical processes)
1897 Hans Buchner shows that extract from yeast cells also works (enzymes)
1920’s-30’s Biochemical pathways (glycolysis, Krebs cycle (TCA), ATP for energy)
1866 Gregor Mendel hereditary factors (genes) and segregation (took 35 years before work recognised)
1876 Walther Flemming identified chromosomes
1900 Walter Sutton chromosome theory of inheritence
1944 Avery et al. genetic transformation in Bacteria)
1953 James Watson and Francis Crick double helix model

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