Ten Themes in the Study of Life
1. Life is organized hierarchically
2. The cell is the unit of structure and function
3. Heritable information is in the form of DNA
4. Structure and function are correlated
5. Organisms exchange matter and energy with their
6. Living systems are regulated
7. The paradox of biology: Unity in diversity
9. Science is a process
10. Science and technology are human endeavors
1 Life is organized hierarchically
Biologists study life on many different scales of size and time
Paul Soreno Paleontologist Joanne Chory Botanist
Flossie Wong-Staal Virologist George Langford Cytologist
Some properties or characteristics of life
Growth and Reproduction
Response to Stimuli Homeostasis Adaptation
Biological structures are highly organized or highly ordered.
Reproduction is a means of self-perpetuation
Growth and development follow a script and a schedule.
2 The cell is the unit of structure and function
1. The cell is the unit of structure of living organisms,
i.e. all living organisms are made of cells.
2. The cell is the unit of function of living organisms,
i.e. the life functions are carried out in the cells.
3. All cells come from pre-existing cells.
4. The activity of a multi-cellular organism is the sum
total of the activities of its constituent cells.
The Two Types of Cells:
Structural organization of eukaryotic and prokaryotic cells
3 Heritable information is in the form of DNA
Biological order implies the
existence of a set of
instructions or code.
The code, more
specifically, the genetic
code is carried on the DNA
molecule. The code is the
sequence of bases.
The code can be copied.
The genetic code is
4 Structure and function are closely correlated,
i. e. form fits function at all levels of organization.
5 Organisms exchange matter and energy with their
environment: energy flow and energy transformation in an
Organisms are energy converters.
6 Living systems are regulated by feedback mechanisms
Feedback regulation is also how a “constant” temperature is
maintained in the home.
No electricity. Thermostat rises above set
Furnace is switch opens point of 22oC on
Room temperature is held relatively
"constant" but it oscillates around 22oC
below set point
of 22oC on the Thermostat Electricity turns
switch closes furnace "on"
7 The paradox of biology: Unity in Diversity:
Unity implies the relatedness of living organisms.
Diversity refers to the number of different kinds of
Typological Species Concept :
A species is a kind or type of organism.
Morphological Species Concept:
Members of the same species resemble one another because
they are derived from similar or like parents.
Biological Species Concept:
Species are groups of interbreeding natural populations that
are reproductively isolated from other such groups.
The hierarchical classification of life catalogues the diversity of life.
Classification is the subject of taxonomy.
Three domains of life: Domain Bacteria, Domain Archaea and
Unity in the Diversity of Life is illustrated by the …
architecture of eukaryotic cilia…
but an even better example is …
…the universal genetic code.
First Second Base Third
Base U C A G Base
Phenylalanine Serine Tyrosine Cysteine U
Phenylalanine Serine Tyrosine Cysteine C
Leucine Serine Stop Stop A
Leucine Serine Stop Tryptophan G
Leucine Proline Histidine Arginine U
Leucine Proline Histidine Arginine C
Leucine Proline Glutamine Arginine A
Leucine Proline Glutamine Arginine G
Isoleucine Threonine Aspartic Acid Serine U
Isoleucine Threonine Aspartic Acid Serine C
Isoleucine Threonine Lysine Arginine A
Methionine/Start Threonine Lysine Arginine G
Valine Alanine Asparagine Glycine U
Valine Alanine Asparagine Glycine C
Valine Alanine Glutamic Acid Glycine A
Valine Alanine Glutamic Acid Glycine G
8 Charles Darwin and Alfred Russel Wallace are
renowned for giving evolution a sound theoretical basis.
Field studies of the Galapagos finches over the past 30 years has
documented evolutionary changes in the physical characteristics of
9 Science is a process; it is a way of doing things.
Careful observation and
measurement provide the raw
data for science both in the
and in the field.
Science is a collaborative and social process.
10 Science and Technology are evident in
Medical and health care … every walk of life.
Campbell and Reece, Chapter 1: pp 1 - 23