The Cell

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The Cell

• Chapter 7

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Anton van Leeuwenhoek developed the first simple
microscope and saw the first living unicellular
organism.   Microscopes Today (See pages 175
and 179)
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1. Compound Light - has a series of lenses that
magnify object in steps. Light goes through
object, then through lens. (1,500 times)
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2. Transmission Electron - aims a beam of
electrons through an object in a vacuum. Images
are two- dimensional. (100,000's
times)   3. Scanning Electron - Sweeps a beam of
electrons over the surface of a
specimen. Produces a three-dimensional image.
(60,000 times)  
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4. Scanning Tunneling - Can show arrangement of
atoms on the surface of a molecule.
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  DISCOVERY OF CELLS  Robert Hooke - Discovered
and named the cell in 1665. Schleiden, Schwann
and Virchow developed the Cell Theory
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CELL THEORY   1.          All organisms are
composed of one or more cells   2. The cell is
the basic unit of organization of
organisms. 3. All cells come, from
pre-existing cells.
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CELL TYPES   PROKARYOTES (See page 177 and 179
of textbook)   Cells that do not have a true
nucleus or internal, membrane-bound
structures.            
Example Bacteria
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EUKARYOTES (See page 177 and 180 of
textbook)   Cells that contain a true nucleus and
internal, membrane-bound structures.   Example
All cells except bacteria or viruses. Plant and
Animal Cells
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  1. PLASMA MEMBRANE - provides a boundary
between the cell and the external environment. It
controls movement of what goes in and out of the
cell. It is selectively permeable. It helps
maintain homeostasis within the cell.  
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Model of a Cell Membrane
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   2. NUCLEUS - Control center of the cell. It
contains DNA and RNA      
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3. RIBOSOME - Site where enzymes and other
proteins an assembled. (Site of protein
synthesis)  
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4. ENDOPLASMIC RETICULUM - A folded system of
membranes which forms a network of interconnected
compartments inside the cell. Provides a large
surface area for chemical reactions to take
place. Are also the site of lipid synthesis for
the cell. The rough ER has ribosomes on its
surface for protein synthesis to take place.
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5. GOLGI APPARATUS - A series of closely
stacked, flatten membrane sacs that receives
proteins and lipids from the ER and delivers them
to the sites in the cell where they are needed.
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6. VACUOLE - Site of fluid storage in a cell.
Larger in plant cells than animal cells.  
Vacuole
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7. LYSOSOME - Organelles that contain digestive
enzymes. (Digest worn out cells, food particles
and viruses and bacteria)
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This is a slice away veiw of a lysosome. The
small sections are the different enzymes used to
breakdown the macromolecules.
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8. MITOCHONDRIA - Organelle in which food
molecules (glucose) are broken down to produce
energy (ATP). Inner membrane is a series of folds
to increase surface area.
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9. CYTOSKELETON - A network of thin elements
which provide support for the cell. Consist of
Microtubules which are hollow protein cylinders
and microfilaments which are solid protein
cylinders.
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10. CILIA and FLAGELLA - Structures for
locomotion. (Not on all cells.) Cilia are short
and hairlike. Flagella are longer and tail-like.
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11. CELL WALL - Found in PLANTS, FUNGI, almost
all BACTERIA and some PROTISTS. It is made of
different substances in different organisms.
Plants have a cell wall composed mostly of
cellulose, while fungi have one composed of
chitin. Animal cells have NO CELL WALL.
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12. CHLOROPLASTS - Organelles that contain
chlorophyll, a green, pigment that traps the
energy from sunlight. Light energy is transformed
chemical energy (glucose) in the chloroplast.
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13. CENTRIOLES - Found only in ANIMAL cells, the
centrioles are small, dark, cylindrical
structures that are made of microtubules and help
during cell division by releasing spindle fibers
which attach to the chromosomes and pull them
apart.
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