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Cells
The Building Blocks of Life
Cells
• Cell: The smallest unit of an organism that
can carry on life functions.
• They are organized, grow, reproduce, use
energy, and respond to stimuli.
Blood cells
Muscle cells
Nerve cells
I. History of Cells
• Robert Hooke was the first to see and name
cells in 1665.
A thin slice of cork
showing cells
• 10 years later in 1675, Anton van
Leeuwenhoek was the first to observe living
cells (bacteria and protozoa)
Microscope he
invented
• The nucleus was not described until 1833
• DNA was not described until the 1950s.
Timeline of Cell Discoveries
1665 cells named
1600
1700
1833 nucleus observed
1800
1675 bacteria observed
Today
1900
1950s DNA
described
Why did it take so long to make these discoveries?
The technology did not exist!
Scratch and sniff paper
x1000
Staple in paper x35
Mascara brush x35
Mosquito head x200
http://www.mos.org/sln/SEM/sem.html
II. Cell Theory
A collection of ideas that forms the foundation
for all biology.
Equivalent to the Theory of Gravity (Physics),
Atomic Theory (Chemistry), and Theory of
Evolution (Evolutionary Biology)
1. All living things are made of one or more
cells.
2. Cells are the basic units of structure and
function in living things. (The building
blocks of life)
3. Living cells only come from other living
cells.
http://ed.ted.com/lessons/the-wacky-history-of-cell-theory
III. Types of Cells
• Prokaryotic-cells that have no membrane
(“skin”) bound nucleus
• DNA floats freely inside the cell
• Seen in the Monera Kingdom (bacteria)
• Eukaryotic-cells with membrane (“skin”)
bound nucleus
• Seen in the protist, fungi, plant, and animal
kingdoms
“Nucleus”
• New-clee-us
NOT
• new-cue-lus
• “nu-cue-ler bombs”
Which cell is
which?
Prokaryotic
or
Eukaryotic?
Prokaryotic vs. Eukaryotic
IV. Single or Multicelluar
• Some organisms are only one cell big.
(unicellular)
diatoms
paramecium
protozoa
• Some organisms are made of millions or
billions of cells working together.
(multicellular)
• In a single celled organism, the cell has to
do all of the life characteristics by itself.
Eating (using energy)
Division
(reproduction)
• In a multicellular organism, each cell is
assigned a specific job. Together, they
make the organism complete.
Blood, nerve, and muscle cells
working together make our heart
complete.
http://www.teachersdomain.org/resource/tdc02.sci.life.stru.singlecell/
The 5 Kingdoms and their Cell Types
Monera Protista Fungi
Unicellular
X
Prokaryotic
Eukaryotic
Animal
X
X
Multicellular
Plant
X
X
X
X
X
X
X
X
The more cells, the more complex
the organism
V. Cell Organization
• Within each cell, there are small structures
that help the cell do its job, they are called
organelles. (tiny organ)
• Cell Membrane: Protective outer covering
for plant and animal cells. It controls what
moves into and out of the cell. (revolving
door)
• Cytoplasm: Supportive, gelatin-like
structure found inside plant and animal
cells. Helps maintain cell shape. (jell-o)
• Nucleus: Directs all cell activities in plant
and animal cells. It also holds a copy of the
chromosomes for the organism. (coach)
• Chromosomes: Found inside the nucleus,
they contain the DNA which holds all of
your hereditary information. (play-book)
• Nucleolus: Found inside the nucleus, it
manufactures ribosomes. (ribosome factory)
• Ribosomes: Makes proteins for cells.
(protein factory)
• Endoplasmic Reticulum (ER): Helps
transport materials around the cell.
(hallway)
• Golgi Apparatus/Bodies: Sorts, packages,
and mails proteins around the cell. (post
office)
• Lysosomes: Contains digestive enzymes
(acids) to help break down food, wastes,
and worn out cell parts. (recycler)
Lysosomes “eat” the tadpole tail.
• Mitochondria: breaks down food into
energy for the organism. (batteries)
Which type of cell would have more
mitochondria? Why?
• Muscle cells or fat cells?
• Vacuole: Storage containers for food, water,
or waste. Plant cells have one large
vacuole. (lunchbox)
Plants with empty vacuoles have
limp leaves and stems
• Cell Wall: Outermost covering of a plant
cell. Provides protection and support for
the plant. (brick wall)
Humans do not have the right
digestive enzymes to break down the
cellulose in cell walls
• Chloroplasts: In plants cells only, it converts
sunlight into food. Chlorophyll inside the
chloroplasts gives plants their green color.
(solar panel)
http://www.youtube.com/watch?v=eo5XndJaz-Y
(Mitochondria and chloroplasts working together)
Organelles all work together to make
a cell function
Organelle review video: http://www.watchknowlearn.org/Video.aspx?VideoID=39968&CategoryID=579
Cells work together to make the
whole organism function
VI. Levels of Organization in
Biology
1 Cells
2 Tissue
3 Organs
4 Organ System
5 Organism
These levels continue through
ecology
5. Organism
6. Population
7. Community
8. Ecosystem
9. Biome
10. Biosphere
Modeling the levels using building
blocks
Level 1 - Cell
Level 2 - Tissue
Level 3 - Organ
Level 4- Organ System
• Circulatory system
Level 5 - Organism
Organ systems
combine to
form an
organism
Level 6 - Population
• A group of alike
organisms
Level 7 - Community
Groups of
different
populations
Level 8 - Ecosystem
• All the
living
and nonliving
things in
an area
Level 9 - Biome
Areas of similar
climate
(weather)
Grassland Biome
Level 10 - Biosphere
• Earth