Chapter 1:
Exploring Life
Unifying Themes in Biology
Evolution~ biology’s core theme;
differential reproductive success
(sex!)
Emergent Properties~ hierarchy of life
The Cell~ all organism’s basic
structure
Heritable Information~ DNA
Structure & Function~ form and
function
Environmental Interaction~ organisms
are open systems
Regulation~ feedback mechanisms
Unity & Diversity~ universal genetic
code
Scientific Inquiry~ observation;
testing; repeatability
Science, Technology & Society~
functions of our world
Hierarchy of Organization
Molecule
Organelle
Cells
Tissues
Organ
Organism
Feedback Regulation: Negative
Accumulation of an
end product of a
process slows that
process
Example: sugar
breakdown generates
ATP; excess ATP
inhibits an enzyme
near the beginning of
the pathway
Feedback Regulation: Positive
An end product
speeds up its
production
Example: blood
clotting in response to
injury
The Process of Science
The Scientific Method
Deductive reasoning
“If….then” Logic
Hypothesis vs.
Theory
Properties of Living things
Early Views of life
Vitalism: The insistence that there
is some big, mysterious extra
ingredient in all living things
Led to idea of spontaneous
generation
Flies came from dead animals
Mice came from Hay
The Redi Experiment
Idea was challenged by scientist
Francesco Redi in 1698.
Designed an experiment where 3
jars contained meat.
Setup 1
One Jar contained meat and had an
open top which would allow the
passage of flies.
(maggots would appear on the meat)
Setup 2
The second jar was covered with an
airtight lid not allowing the passage
of flies.
(no maggots would appear on the meat)
Setup 3
The third was covered by a screen
allowing passage of eggs, but not
flies.
(few maggots would appear on meat)
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
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”)
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.
PROPERTIES of LIFE
Living things must Have DNA.
(Universal Genetic Code?)
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 lifespan.
Includes cell differentiation.
Includes organ development
Includes aging & death.
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.
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.
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