Cells: The Building Blocks of Life
What is Life?
An organism is a living thing.
Six characteristics of all living
things are:
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Cellular organization
Contain similar chemicals
Use energy
Grow and develop
Respond to their surroundings
Reproduce
Cells are the basic building blocks
of all living things.
The basic unit of
structure and
function.
Cellular organization
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Cells
Tissue
Organs
Organ systems
Unicellular
An organism with
only one cell.
Multicellular
An organism with
many cells.
Chemicals of Life
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Water is the most
abundant chemical in
cells.
Proteins and lipids are
the building materials of
cells.
Nucleic acids are the
genetic material that
direct the cell’s activities.

Carbohydrates provide
the cell with energy.
Cells use energy for all life
processes.
Ex: grow, repair
cells,
Digest food, respond
to stimuli, reproduce
Growth- the process of becoming
larger.
Development- the
process of change
that occurs during
and organism’s life.
Response to Surroundings

Stimulus- A change in an
organism’s surroundings
that causes an organism
to react. Example: light,
sound, temperature,
chemicals, pressure, etc.

Response- An action or
change in behavior due
to a stimulus. Example:
blinking, shivering,
sweating, jumping,
crying, pupils changing
shape, etc.
Reproduction
Produce offspring
that are similar to the
parents.
Life Comes From Life
Spontaneous
Generation-mistaken
theory that living
things arise from
nonliving things.
Experiments to disprove
spontaneous generation.
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Francesco Redi
Flies do not
spontaneously arise
from decaying meat.

Louis Pasteur
Spontaneous generation
does not occur with
bacteria.
Redi’s Experiment

Manipulated
(independent variable)
was the covering on the
jar.
Pasteur’s Experiment

Manipulated
(independent variable)
was boiling the broth in
one flask.
The Needs of Living Things
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Energy
Water
Living space
Stable internal conditions (homeostasis)
Organisms use food as their source
of energy.
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Autotrophs- (auto
means self; troph
means feeder )
organisms that make
their own food.

Heterotrophs- (heteromeans other) organisms
that cannot make their
own food.
Invention of the microscope made
it possible to discover cells.
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Robert Hooke observed a thin slice of cork and
discovered rectangular shaped structures he
called cells.
Anton van Leeuwenhoek observed pond water
and called the small organisms “animalcules”
Scientists responsible for the cell
theory.
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Matthias Schleiden- stated all plants are made
of cells.
Theodor Schwann- stated all animals are made
of cells.
Rudolf Virchow- stated all cells come from
other cells.
The Cell Theory
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All living things are composed of cells.
Cells are the basic unit of structure and
function in living things.
All cells are produced from other cells.
Plant cells
Cork cell
Onion cell
Elodea cells
Animal Cells
Blood cells
Frog blood cells
Cheek Cells