Transcript Microscope and Cells

Chapter 4
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Schwann, Schleiden and Virchow are credited
with coming up with the basics of the cell
theory
3 components:
◦ 1.All living organisms are made up of cells
◦ 2.Cells are the basic units of structure and function
in living organisms.
◦ 3.All cells come from cells that existed before them
by cellular reproduction.
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http://www.youtube.com/watch?v=AeygTtDx2W8
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Every cell has the following main
characteristics:
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Cell membrane
Cytoplasm
DNA
Ribosomes
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Antone von Leeuwenhoek assembled the first
microscope that was useful for scientific
research.
Compound light microscopes reflect light
through a set of lenses and the specimen to
magnify the specimen.
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See handout for the parts of the microscope – you must know it.
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http://www.youtube.com/watch?v=3emmlXcV-MU&feature=related
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Two important characteristics that determine
the quality of a light microscope:
◦ Magnification – an increase in the apparent size of
an object. We calculate magnification by the
following:
Magnification of eyepiece x magnification of
objective lens = total magnifying power
• Resolution – the measure of clarity of an image. As
the magnification increases, the resolution of the
image decreases.
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Some microscopes use beams of electrons for
magnification instead of light – electron
microscopes
Scanning electron microscope (SEM) – used to
study the detailed architecture of the surface
of the object. Forms a 3D image, but does
not show the inside of the object.
Transmission electron microscope (TEM) –
used to provide a detailed 2D image of the
inside structure of the object that is viewed.
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http://www.cellsalive.com/howbig.htm
Cells are microscopic, they are visible only
with light microscopes.
Most of their size ranges from 1-100 µm.
Cells are small, because they have to be
able to carry materials from one side of the
cell to the next in a short period of time.
Cells must have a large enough surface area
to be able to take in nutrients and oxygen
and release waste quickly.
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Prokaryotic cells –
◦ small cells (about 1-10 µm) that do not have a
nucleus and membrane-bound organelles
◦ Found in bacteria and archaebacteria
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Prokaryotic Cell Organelles:
◦ Nucleoid region – part of the prokaryotic cell where
the DNA is found
◦ Cell membrane – innermost covering of the cell
◦ Cell wall – outside of cell membrane, made up of a
special mix of polysaccharides and proteins
(antibiotics break it down)
◦ Capsule – outside of the cell wall, protective covering
(not all bacteria have it)
◦ Flagella (sing. Flagellum) – long, whiplike structure
that moves bacteria
◦ Pili – short, hair-like projection used to stick to other
surfaces and for conjugation (exchange of genetic
materials between bacteria)
◦ Cytoplasm – jelly-like fluid that dissolves substances
and holds organelles
◦ Ribosomes – organelles that make proteins in the
cytoplasm
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http://www.ted.com/talks/lang/eng/bonnie_bassler_on_how_bacteria_communicate.html
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Protists, Fungi, Plants, and Animals
Have nucleus and membrane-bound
organelles
Much larger and more complex than
prokaryotic cells.
Reproduce sexually and asexually
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Nucleus
◦ Control center of cell; contains most of the cell’s
DNA
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Nucleolus
◦ Location where ribosomes are synthesized
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Nuclear pore
◦ Allows RNA to move in and out of nucleus
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Ribosomes
◦ Protein synthesis
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Rough ER
◦ Comprised of a network of tubes and flattened
sacs.
◦ Continuous with plasma membrane and nuclear
membrane
◦ Site of protein synthesis (consists of ribosomes)
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Smooth ER
◦ Site of lipid and carbohydrate metabolism
◦ No ribosomes
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Golgi Apparatus
◦ Connected with ER; flattened disc-shaped sacs,
stacked one on top of the other
◦ Modification, storage, and packaging of proteins.
◦ “tags” proteins so they go to the correct
destination.
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Lysosomes (in animal cells and some protists)
◦ Digestion of nutrients, bacteria, and damaged
organelles; destruction of certain cells during
embryonic development
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Peroxisomes
◦ Diverse metabolic processes with breakdown of
H2O2 by-product
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Vacuoles
◦ Digestion (like lysosomes); storage of chemicals,
cell enlargement; water balance
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Chloroplasts
◦ Conversion of light energy to chemical energy of
sugars (site of photosynthesis)
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Mitochondria
◦ Conversion of chemical energy of food to chemical
energy of ATP
◦ “Power House” of cell
◦ Bound by double membrane
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Cytoskeleton (including cilia, flagella, and
centrioles in animal cells)
◦ Maintenance of cell shape; anchorage for
organelles; movement of organelles within cells;
cell movement; mechanical transmission of signals
from exterior of cell to interior.
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Cell walls (in plants, fungi, and protists)
◦ Maintenance of cell shape and skeletal support;
surface protection; binding of cells in tissues