Download The Three Domains of Life

Chapter 1
By Dr. Par Mohammadian
Biology
THE SCOPE OF BIOLOGY
• Biology is the scientific study of life
• Interactions between different kinds of organisms
affect the lives of all
– Example: Flying foxes and eucalyptus trees
• Ecosystem
Life’s levels of organization define the
scope of biology
• A structural hierarchy of life, from molecules to
ecosystems, defines the scope of biology
• An ecosystem consists of:
– all organisms living in a particular area
– all nonliving physical components of the environment
that affect the organisms
(soil, water)
– Ecology is the branch of biology that investigates
these relationships between organisms and their
environment
• At the top of life’s
hierarchy is the
ecosystem
• Ecosystems include:
– all the organisms in
an area, which make
up a community
– interbreeding
organisms of the
same species, a
population
• Cells & Diversity
Cells – Structural and Functional Units
of Life
• The cell is the lowest level of structure that can
perform all activities required for life
– All organisms are composed of cells
• We can distinguish two major types of cells
– Prokaryotic
– Eukaryotic
• The genetic information in DNA underlies all of
the features that distinguish life from nonlife
–
–
–
–
–
–
–
Order: e.g. Sunflower; highly ordered str
Regulation: e.g. regulation of amount of blood
Growth and development
Use of energy from the environment
Response to environmental stimuli
Ability to reproduce
Evolutionary change
Life in Its Diverse Forms
The diversity can be arranged into three
domains
• Diversity is the hallmark of life
– The diversity of known life includes 1.7 million
species
– Estimates of the total diversity range from 5 million
to over 30 million species
The Three Domains of Life
• The three
domains of life
are
– Bacteria
– Archaea
– Eukarya
• Eukarya
includes at
least four
kingdoms
–
–
–
–
Protista
Plantae
Fungi
Animalia
NAME
KEY CHARACTERISTICS
EXAMPLES
of Kingdoms
MONERA
(Also known as
Archaea; also
called
Archaebacteria
PROTISTA
FUNGI
UNICELLULAR
PROKARYOTIC
MOSTLY UNICELLULAR
EUKARYOTIC
MOSTLY MULTICELLULAR
EUKARYOTIC
HETEROTROPHIC
BACTERIA
BLUE-GREEN ALGAE
AMEBA
PARAMECIUM
EUGLENA
ALGAE
MUSHROOMS
MOLDS & MILDEWS
YEAST (unicellular)
PLANT
MULTICELLULAR
EUKARYOTIC
AUTOTROPHIC
CELL WALLS made of CELLULOSE
MOSS
FERNS
FLOWERING PLANTS
BUSHES
TREES
ANIMAL
MULTICELLULAR
EUKARYOTIC
HETEROTROPHIC
MOTILE
SPECIALIZED SENSE ORGANS
INSECTS
JELLYFISH, HYDRA
CRABS
FISH
BIRDS
LIONS,TIGERS,BEARS
• Evolution
• The theory of
natural selection
explains the main
mechanism
whereby all
species of
organisms
change, or evolve
• The Process of Science
THE PROCESS OF SCIENCE
• The word science is derived from a Latin verb
meaning “to know”
– Science is a way of knowing
– Science developed from our curiosity about ourselves
and the world around us
THE PROCESS OF SCIENCE
Scientists use two main approaches to learn about nature
• In discovery science, scientists describe some
aspect of the world and use inductive reasoning
to draw general conclusions
– Example: scientists have
described how newborn
flying foxes cling to their
mother’s chest for the
first weeks of life
• In hypothesis-driven science, scientists use the
“scientific method”
– They propose a hypothesis
– They make deductions leading to predictions
– They then test the hypothesis by seeing if the
predictions come true
• Experiments designed to test hypotheses must be
controlled experiments
• Control groups must be tested along with
experimental groups for the meaning of the
results to be clear
Human experiments and drug testing!