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THE CELL
The Smallest Unit of Life
Alison Birkmeyer
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Copyright 1996-2001 © Dale Carnegie & Associates, Inc.
THE CELL THEORY
• Observations by the following three people formed
the cell theory.
• Schleiden- plants
• Schwann – animals
• Virchow - cells come from other cells
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CELL THEORY
1.
All Living Things are made up of one or
more cells.
2.
Cells are the basic units of structure and
function in organisms.
3.
All cells arise from preexisting cells
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Looking at cells
• Robert Hooke – 1st to see cells. (cork)
• Anton van Leeuwenhoek – living creatures
(animalcules)
Two types of microscopes
• Compound LIGHT - uses light and two or more
lenses.
• Electron – uses a beam of electrons.
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Compound Light
• Uses two or more lenses
• Uses light
• Low magnification
• View living or dead specimens
• Magnification= ocular lens X objective lens.
ex. Ocular = 10x ; obj. lens = 10x
Total magnification = (10 X 10) = 100x
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Electron Microscope
• Uses a beam of electrons
• Specimens must be placed in a vacuum
• Cannot be used to view living things.
• Very powerful magnification
• Two types of electron microscopes are
Transmission and Scanning
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CELL SIZE
• Surface are is an important factor in
limiting cell growth because
The cell may become too large to take in
enough food and to remove enough
waste.
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Common Features of ALL Cells
• Cell Membrane
• Cytoplasm
• Ribosomes
• Cytoskeleton
• DNA
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Cell Types
• Prokaryote
• Eukaryote
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Prokaryote
• Functions are controlled by the DNA
Plasmid not the nucleus
(NO NUCLEUS)
• Modern prokaryotes (most or majority)
are generally known as BACTERIA
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Prokaryote
• No internal membrane bound organelles
• Do NOT have a nucleus
• Oldest cell types –Their evolution preceded
that of eukaryotes
• Most are unicellular bacteria
• Ex. Old Kingdom Monera (BACTERIA)
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EUKARYOTE
• All other organisms (except bacteria) are
eukaryotes
• The cells of Animals; Plants, Fungus,
Protists are Eukaryotic (you are an
Eukaryotic)
• Specialized structures called organelles that
perform a specific function
• Only eukaryotic cells have membrane
bound organelles
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EUKARYOTE
• A cell with a well defined nucleus
surrounded by a nuclear envelope is
an EUKARYOTE
• EUKARYOTE cells have a system of
internal membranes
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CELL MEMBRANE
• Gate keeper- Allows materials to enter and
leave
• Structure that regulates what enters and
leaves the cell
• All substances that enter or leave a cell must
cross the cell membrane
• Is selectively permeable – allows only some
things to pass in or out.
• Encloses the contents of the cell
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CYTOSKELETON
• Provides the internal framework of a
cell
• Mesh like network of protein fibers
that supports the shape of the cell
• Microtubules – highway system
• Microfilaments - support structures
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CYTOPLASM
• Gel-like substance found within the cell
• Supports the cell
• Region of the cell within the membrane
that includes the fluid; cytoskeleton; and
all of the organelles except the nucleus
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CELL ORGANELLES
(Know ALL of these & functions)
1 Nucleus
2 Ribosomes
3 Endoplasmic Reticulum (rough and smooth)
4 Golgi apparatus
5 Lysosome
9. Chromosomes
6 Mitochondria
10. DNA
7 Vesicle or Vacuole
11. Cell Wall
8 Centrioles
12. Plastids
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NUCLEUS
• The nucleus houses a cell’s DNA, which
contains heredity information.
• DNA stores information that directs the
activities of the cell
• Has a double membrane surrounding the
nucleus called the nuclear envelope
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NUCLEUS
• Contains chromosomes
• Chromosomes are rod shaped
structures that are made up of DNA and
protein
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RIBOSOMES
• Site of PROTEIN synthesis in a cell
• In the cell, proteins are made on the
RIBOSOMES
• Free (found floating in the cytoplasm
• Attached (attached to ER)
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ENDOPLASMIC RETICULUM
• Helps to maintain homeostasis by
moving substances from one parts of
the cell to another
• Rough ER has RIBOSOMES embedded
on its surface.
• Smooth ER has no ribosomes embedded
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Golgi Apparatus
• Packaging and distribution center of
the cell
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LYSOSOME
• Organelle that contains digestive enzymes
that breaks down cellular materials (CHO;
proteins, nucleoc acids, lipids, etc…)
• Referred to as a suicide sac
• Waste management system
• Digests and recycles cellular components
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MITOCHONDRIA
• POWER HOUSE (ENERGY)
• Mitochondria contain DNA
• Produces most of the cell’s energy
• Stores this energy in cpds called ATP
• More energy requirements – more mitochondria
• Ex. Muscle cells have more that skin cells
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CHLOROPLASTS (PLANTS)
• Use light energy to make CHO (sugar)
Glucose.
• The main organelle associated with plant
photosynthesis.
• Site of Photosynthesis
• Contain their own DNA
• Thought to be descendants of prokaryotic
cells.
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CELL WALL
• NOT FOUND IN ANIMAL CELLS
• Support and protection for plants,
bacteria, and fungi
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CILIA and FLAGELLA
• Cilia – shorthair like structures that
protrude from the surface of a cell and
are packed in tight rows (movement)
• Flagella – long whip like structure used
for movement
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Major differences between
PLANT and ANIMAL cells
• PLANT: has the following
– Chloroplasts/Chlorophyll
– Large central vacuole
– Cell Wall = made of cellulose
– Plant cells are surrounded by a CELL WALL
• PLANT: do NOT have
– Centrioles
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Animal Cells vs Plant cells
KNOW
• Animal cells do NOT have a cell wall
• Animal cells do NOT have Chloroplasts
• Animal cells do NOT have a central vacuole –
they have smaller vesicles
• Animal cells have Centrioles
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What identifies a cell as an Eukaryote?
– The nucleus
• Chromosomes are found in the?
– NUCLEUS
• Recognize an animal cell because(Main
Reasons?
– NO CELL WALL
– NO CHLOROPLAST
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DRAW and LABLE
ANIMAL CELL
1. Nucleus
7. Nuclear Membrane
2. Mitochondria
8. Cytoplasm
3. ER
9. Chromosomes (DNA)
4. Lysosome
10. Ribosomes
5. Golgi Apparatus
6. Cell Membrane
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DRAW and LABLE
PLANT CELL
1. Nucleus
9. Nuclear Membrane
2. Central Vacuole
10. Ribosomes
3. Cell Wall
11. Golgi Body
4. Cell Membrane
5. ER
6. Chloroplast
7. Mitochondria
8. Chromosomes (DNA)
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