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Chapter 7
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Robert Hooke:
1665 - looked at a thin slice of cork
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Anton van Leeuwenhoek:
1674 - observed living cells in pond water
In 1839, Schwann and Schleiden suggested that
cells were the basic unit of life.
In 1855, Rudolf Virchow concluded that all cells
come from pre-existing cells.
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All living things are composed of cells
Cells are the basic units of structure and
function in living things
New cells are produced from existing cells
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Cells that do not contain a nuclei.
Generally smaller and simpler than eukaryotic
cells.
EX: Bacteria
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Contain a nucleus where genetic material is
separated from the cell by a membrane –
“membrane bound”
Larger and more complex
Contains specialized structures (organelles)
and internal membranes
Some are single-celled, others are large,
multicellular organisms
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A factory with different tasks performed at different locations within the
factory.
1 Nucleolus
2 Nucleus
3 Ribosomes (little dots)
4 Vesicle
5 Rough endoplasmic reticulum
6 Golgi apparatus
7 Cytoskeleton
8 Smooth endoplasmic reticulum
9 Mitochondria
10 Vacuole
11 Cytosol
12 Lysosome
13 Centrioles within Centrosome
14 Cell membrane
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Means “little organs”
Cytoplasm:
◦ Liquid/gelatenous part of the cell where organelles
are suspended
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Nucleus:
◦ Contains the DNA (coded instructions for making
proteins and other important molecules)
◦ Cell Song http://www.youtube.com/watch?v=ZK6YP1Smbxk
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Nuclear envelope (membrane): surrounds the
nucleus
◦ Dotted with nuclear pores that allow material to
move into and out.
◦ RNA, DNA, and protein can move in and out.
◦ Chromatin: grainy material in the nucleus
◦ Chromosomes: condensed chromatin
◦ Nucleolus: dense circular area inside, where
assembly of ribosomes begins
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Proteins are assembled here!!!
Found throughout the cytoplasm
Produce proteins by following coded
instructions from the nucleus.
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Internal membrane system
The site where lipid components of the cell
membrane are assembled, along with
proteins and other materials that are
exported from the cell.
Rough ER: involved in the synthesis of
proteins.
◦ Contains ribosomes
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Smooth ER: contains
collections of
enzymes that
perform specialized
tasks.
Ribosomes are not
found on it.
Synthesis of
membrane lipids and
the detoxification of
drugs.
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Modify, sort, and package proteins and other
materials from the endoplasmic reticulum for
storage in the cell or secretion outside the
cell.
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Small organelles filled with enzymes.
Digestion, or breakdown of lipids,
carbohydrates, and proteins into small
molecules that can be used by the rest of the
cell.
Also breaks down organelles that have
outlived their usefulness
Tay-Sachs disease: traced to lysosomes that
fail to function properly.
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Mitochondria: organelles that convert the
chemical energy in food into compounds
more convenient to use.
Makes energy
Composed of two membranes:
◦ Outer and inner membranes
◦ Folded inner membranes increase surface area for
more energy production
◦ Mitochondria come from the cytoplasm of the egg
cell ( from mother)
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Chloroplast: capture energy from sunlight
and convert it into chemical energy in a
process known as photosynthesis.
Found in plants and photosynthetic
organisms.
Surrounded by two membranes:
Contain green pigment called chlorophyll
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Helps support the cell.
A network of protein filaments that maintains
cell shape.
Also involved in movement.
Microfilaments: threadlike structures made of
a protein called actin.
Produce a tough flexible framework that
supports the cell.
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Microtubules: hollow structures made up of
proteins known as tubulins.
◦ Play a role in cell shape
◦ Important in cell division
◦ Cilia and flagella: movement
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Centrioles: located near the nucleus and
helps to organize cell division.
◦ Not found in plant cells
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Regulates what enters and leaves the cell
Composition: lipid bilayer
Fluid Mosaic Model
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Transport and channel proteins: help to move
material across the cell membrane.
Carbohydrates: allow individual cells to
identify one another
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Lie outside the cell membrane.
provide support and protection for the cell.
Cellulose: principle component of cell wall
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the mass of the solute in a given volume of
solution
Equilibrium: when the concentration of the
solute is the same throughout the system
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Particles move from an area of high
concentration to an area of low
concentration.
Does not require energy
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The diffusion of water through a selectively
permeable membrane.
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Isotonic: the concentration of solutes is the
same inside and outside the cell
Hypertonic: solution has a higher solute
concentration than the cell
Hypotonic: solution has a lower solute
concentration than the cell.
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Molecules that cannot diffuse across the cell
membrane’s lipid bilayer on their own move
through protein channels instead.
No energy is required
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against the concentration gradient (low to
high).
Requires energy
Carried out by transport proteins.
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Taking material into
the cell by means of
infoldings, or
pockets, of cell
membrane
◦ Phagocytosis
◦ Requires
considerable amount
of energy
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the membrane of
the vacuole
surrounding the
material fuses with
the cell membrane
forcing the
contents out of the
cell.