Properties of Living things
1
Early Views of life
• 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
2
The Redi Experiment
• Idea was challenged by scientist
Francesco Redi in 1698.
• Designed an experiment where 3 jars
contained meat.
3
Setup 1
• One Jar contained meat and had an
open top which would allow the passage
of “ethers” and flies.
– (maggots would appear on the meat)
4
Setup 2
• The second jar was covered with an
airtight lid allowing the passage of
neither “ethers” or flies.
– (no maggots would appear on the meat)
5
Setup 3
• The third was covered by a screen
allowing passage of “ethers”, but not
flies.
– (no maggots would appear on meat)
6
Conclusion
• 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
• All life comes from preexisting life
7
PROPERTIES of LIFE
• 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”)
8
PROPERTIES of LIFE
• 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.
9
PROPERTIES of LIFE
• Living things must Have DNA.
• (Universal Genetic Code?)
10
PROPERTIES of LIFE
• 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.
11
PROPERTIES of LIFE
• 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.
12
PROPERTIES of LIFE
• 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.
13