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Properties of
Living things
·
Early
Views of life
o Vitalism:
§
Life
was generated by a objects acquisition of “Ethers”
which would manifest animate it.
§
Led
to idea of spontaneous generation
·
Flies
came from dead animals
·
Mice
came from Hay
§
Idea
was challenged by scientist Francesco Redi in
1698.
·
Designed
an experiment where 3 jars contained meat.
o One Jar contained meat and
had an open top which would allow the passage of “ethers” and flies. (maggots
would appear on the meat)
o The second jar was covered
with an airtight lid allowing the passage of neither “ethers” or flies. (no
maggots would appear on the meat)
o The third was covered by a
screen allowing passage of “ethers”, but not flies. (no maggots would appear on
meat)
Setup 1 Setup 2 Setup 3
o Since the third setup would
theoretically allow the passage of “ethers”, but no maggots appeared, it was
implied that flies were the source of the maggots.
·
Led
to the theory of Biogenesis
o All life comes from
preexisting life
PROPERTIES
of LIFE
1. Be
made of Cells.
·
The
Cell is the basic unit of life
·
Is
self contained and possesses a barrier (membrane) which separates itself from
the environment.
·
Two
types of organisms.
·
Unicellular - One celled organism (Uni=1)
·
Multicellular - Many cells (Multi=”many”)
2.
Living Things must Reproduce.
·
Must
be able to create more of it’s own kind
·
Two
types of reproduction:
·
Sexual - Two parent organisms combine genetic material to produce the
offspring.
·
Asexual - When a single organism can divide or “bud” to create it’s offspring
without another of it’s species.
3. Living
things must Have DNA.
·
(Universal
Genetic Code?)
4. Living
things must Grow & Develop.
·
Growth refers to two processes.
·
Increase
in the number of cells.
·
Increase
in the size of cells.
·
Development refers to changes in the organism which occur
through it’s life-span.
·
Includes
cell differentiation.
·
Includes
organ development
·
Includes
aging & death.
5. Living
things obtain & use energy.
·
Energy
is used by all living things for growth, development & reproduction.
·
Life
processes which result in “building” the organism ia known as Anabolism.
·
Life
process where energy is extracted by “breaking-down” substances is called Catabolism.
6. Living things must Respond (or react) to their environment in some
way.
·
Something
which causes an organism to react is known as a Stimulus
(stimuli).
·
The
ability of an organism to react is called Irritability.
·
Most
responses are geared for maintaining Homeostasis.
·
Homeostasis is a process where an organism maintains a stable
internal environment so life can continue.
·
Some
examples include temperature, pH, and water content of the cell.
7.
Must Maintain homeostasis.
·
Internal
stable set of internal conditions allowing the chemical reactions of life to
occur.