Download Cells

Cells: Prokaryotes v. Eukaryotes
(extracts of 7-1 & ch19)
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7-1 Life Is Cellular
The Discovery of the Cell
Early Microscopes
In 1665, Robert Hooke
used an early compound
light microscope to look at
a thin slice of cork, a plant
material.
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7-1 Life Is Cellular
The Discovery of the Cell
Early Microscopes
At the same time, Anton van Leeuwenhoek used a microscope
to observe pond water and other things.
Daphnia – water insect
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7-1 Life Is Cellular
The Discovery of the Cell
What is the cell theory?
In 1838, Matthias
Schleiden – all plants were
made of cells.
In 1839, Theodor Schwann
– all animals were made of
cells.
In 1855, Rudolph Virchow
– new cells were created
only from division of
existing cells.
These discoveries led to
the cell theory.
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7-1 Life Is Cellular
The Discovery of the Cell
Cell Theory is a SCIENTIFIC THEORY!
Scientific Theory: A well
tested explanation that
unifies a broad range of
observations.
•Scientific Theory used to
make accurate predictions
about new observations and
situations.
•Scientific Theory can be
revised according to new
evidence
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7-1 Life Is Cellular
The Discovery of the Cell
cell theory
• All living things are composed of one
or more cells.
• Cells are the basic units of structure
and function in living things.
» Use genetic code (DNA)
» Over generations mutations accumulate and
lead to changes over time
» Get energy and materials from environment to
run cellular metabolism
» Respond to the external environment
» Maintain homeostasis (stable internal
environment)
• New cells are produced from existing
cells.
» Grow and develop
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7-1 Life Is Cellular
Exploring the Cell
Light microscope V. Electron
microscope
Electron Microscope
Up to 100,000X
Preserved cells only
Scanning EM (3D image)
Transmission EM (2D cross section)
TEM
Light micrograph (LM)
Up to 1000X
SEM
Live or preserved cells
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7-1 Life Is Cellular
DNA kept separate from
the cell’s cytoplasm by
the nuclear membrane
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Figure
End4.4
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Scientist’s study of different organisms’ cell structure and DNA lead
them to group organisms into 3 different domains
ArchaeEubacteria: bacteria: Protists Plants Fungi Animals
common
bacteria UC
Oldest
bacteria
type
UC
UC&MC
MC
UC&MC
MC
First Eukaryotes
(Has nucleus)
UC = unicellular
MC= multicellular
First cells (prokaryotic) 3.5 billion years ago
7-1 Life Is Cellular
Prokaryotes and Eukaryotes
Prokaryotes and Eukaryotes
Prokaryote focus:
The smallest, simplest life forms are prokaryotes—unicellular
organisms that lack a nucleus.
Biologists divided them into two different domains: the Eubacteria and
the Archaebacteria.
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19–1 Bacteria
Classifying Prokaryotes
Archaebacteria- Ancient
bacteria
Achaebacteria’s DNA is more
similar to eukaryotes than
eubacteria!.
They live in extreme environments
(why also known as
extremeophiles)
●Methanogens live in oxygenfree environments, such as
thick mud and animal digestive
tracts.
●Other archaebacteria live in
salty environments
● or in hot springs where water
temperatures approach the
boiling point.
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19–1 Bacteria
Classifying Prokaryotes
Thermophiles of Yellowstone
Produce Beautiful colors
Grand Prismatic Spring Yellowstone.
•This type of Extremophile requires
temperatures above 45oC (113oF)
to survive.
•Wow: for most organisms,
proteins and nucleic acids would
denature at these hot
temperatures.
•Thermophiles source of enzymes
used in DNA biotechnology
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19–1 Bacteria
Classifying Prokaryotes
Eubacteria include organisms that live in a
variety of environments, including:
●in fresh and salt water
● on land
●in the human body
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Structures of Prokaryotic Cells
Nucleoid region – area where DNA
is coiled in the cytoplasm. DNA is
in direct contact with the rest of the
cell
Ribosome
Plasmid – smaller circular DNA
molecules – stores genes easily
shared with other bacteria
Ribosomes – where proteins are
made
cell membrane – encloses the
cytoplasm of the prokaryotic cell,
regulates what chemicals enter and
leave the cell.
Flagella
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DNA
Plasmid
Pili
Structures of the Prokaryotic Cell
Cell wall – rigid, composed of lipids,
carbohydrates and protein.
Protects the cell and maintains its
shape
Pili – short surface projections
found in some prokaryotes. Helps
attach bacteria to surfaces
Flagella – long whiplike extensions
found in some prokaryotes. Propel
cell through liquid environments
Not all bacteria the a same shape!
•Bacilli (rod)
•Cocci (round)
•Spirilla (spiral)
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19–1 Bacteria
Importance of Bacteria
Bacteria are vital to the living world.
Autotrophs: Some are producers that capture energy by
photosynthesis.
Heterotrophs: using living organisms as food source.
●decomposers
●Nitrogen fixing bacteria
●Pathogens: cause disease
• Some bacteria damage the cells and tissues directly by
breaking down the cells for food.
• Others By produce toxins that
makes you sick
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19–3 Diseases Caused by
Bacteria and Viruses
Bacterial Disease
Bacterial Disease in Humans
Bacterial Diseases
Growth of pathogenic
bacteria disrupts the body’s
equilibrium by interfering
with its normal activities and
producing disease.
Antibiotics
Chemicals that kill bacteria
w/o harming your cells
–Ex: Penicillin disrupts
bacterial cell wall
production
–Does not work on Viral
infections
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Importance of Bacteria
19–1 Bacteria
Still other bacteria have
human uses.
●foods
●Genetically engineered
bacteria used to produce
medicine
●production of some vitamins
especially vitamins K in
human intestines
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7-1 Life Is Cellular
Prokaryotes and Eukaryotes
Compare &
Contrast: What are
the characteristics
of prokaryotes and
eukaryotes?
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7-1 Life Is Cellular
Prokaryotes and Eukaryotes
Prokaryotes
Prokaryotic cells have genetic material
that is not contained in a nucleus.
–do not have membrane-bound organelles.
–cells are generally smaller and simpler than
eukaryotic cells.
–Bacteria (both archaebacteria and eubacteria) are
prokaryotes.
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7-1 Life Is Cellular
Prokaryotes and Eukaryotes
Prokaryotes and
Eukaryotes
All cells have DNA to store
hereditary information but where
is it in the cells?
Eukaryotes have a nucleus –
DNA surrounded by a a nuclear
envelope membrane separating
DNA from the rest of the cell
Eukaryotes have membrane
bound organelles – like
mitochondria and Endoplasmic
Reticulum
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7-1 Life Is Cellular
Prokaryotes and Eukaryotes
Eukaryotes
●Cells highly specialized
●In multicellular species
groups of cells can form
tissues
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7-1 Life Is Cellular
Prokaryotes and Eukaryotes
Eukaryotic cells: Build the structures of
Plants, animals, fungi, and protists.
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7-1 Life Is Cellular
Prokaryotes and Eukaryotes
Compare and contrast
Pro
Both
Eu
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