A View of
Life
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• The Human Genome Project mapped
the complete set of human genes
• Genomics analyses the DNA
sequence of an organism
• While genomics will lead to
breakthroughs in science, it also
raises ethical concerns
– Safeguarding the privacy of
genetic information, for example
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• Living organisms composed of cells
– Unicellular organisms
• Single cell
– Multicellular organisms
• Many cells organized to form
tissues, organs, and organ
systems
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• Cells
– Plasma membrane regulates
passage of materials
– Specialized molecules (usually
DNA) contain genetic
instructions
– Internal structures called
organelles perform specific
functions
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• Types of cells
– Prokaryotic cells, exclusive to
bacteria and microscopic
organisms
– Eukaryotic cells contain a
variety of organelles, including a
nucleus, which houses DNA
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• Biological Growth
– Increase in the size of cells, the
number of cells, or both
• Development
– Includes all the changes that take
place during an organism’s life
– Structures and body form are
adapted to an organism’s functions
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• Metabolic processes
– Chemical reactions and energy
transformations
– Essential to nutrition, growth
and repair of cells, and
conversion of energy
– Regulation of metabolic
processes maintains homeostasis
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• Stimuli
– Physical or chemical changes in the
internal or external environment
– The organism responds to, for
example, changes in
• Light
• Temperature, pressure, or sound
• The chemical composition of soil
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• Locomotion
– Simpler organisms
• Amoeboid movement
• The beating of cilia or flagella
– Animals
• Move by contracting muscles
• Some are sessile and have cilia or
flagella
– Plants respond to light, water, etc.
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Asexual and Sexual Reproduction
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• Adaptation
– Populations evolve to better survive
– Adaptations
• Characteristics that enhance an
organism’s ability to survive in a
particular environment
• May be structural, physiological,
behavioral, or a combination
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Biological
Organization
Hierarchy
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• The cell
– Consists of atoms and
molecules
– Is the basic unit of life
– In multicellular organisms,
associates to form tissues
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• Tissues
– In animals, an example is muscle
– In plants, an example is
epidermis
• Tissues are organized into organs
• Tissues and organs form organ
systems
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• Population
– Members of a species that live in
the same area at the same time
• Community
– Populations that live together and
interact
• Ecosystem
– A community and the environment
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• To carry on life processes, an
organism must have
– Precise instructions
– Communication among cells
• This information is coded and
delivered by
– Chemical substances
– Electric impulses
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• DNA is the large molecule that
makes up genes
• Genes specify instructions for
making every living organism
• Watson and Crick worked out
structure of DNA in 1953
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DNA consists
of two
chains of
atoms
twisted into a
helix
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• DNA contains “recipe” for
proteins
• Proteins determine structure
and function of cells and
tissues
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• In multi-cellular organisms,
communication with and among
cells is critical
• Some proteins are important in
this communication
• Cell-to-cell communication is a
complex process called cell
signaling
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• Information transmitted from
one part of the body to another
is important in regulating life
processes
• Information is transmitted by
– Hormones
– Neurotransmitters and their
receptors
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• Evolution is the unifying
concept of biology
• Biology
– Hierarchical classification
scheme
– Identifies the approximately
1.7 million species of living
organisms
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• Systematics studies the
diversity of organisms and
their evolutionary relationships
– Taxonomy is the science of
naming and classifying
organisms
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• Binomial system of nomenclature
– Developed in the 18th century by
Linnaeus, a Swedish botanist
– Names and classifies organisms
– Basic unit is a species
– Each species assigned a two-part
name
– Genus species
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• Binomial system of
nomenclature uses a series of
taxonomic categories from
species to domain
• Domain, Kingdom, Phylum,
Class, Order, Family, Genus,
species
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•Each
category is
more general
and
more inclusive
than the one
below it
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• Natural selection
– Theory of evolution developed
by Darwin and Wallace
– The Origin of Species by
Natural Selection published in
1859
– Sometimes called “survival of
the fittest”
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• Natural selection based on four
observations
– Members of a species show
variation
– Organisms produce many more
offspring than will survive
– Organisms compete
– Only some survive to reproduce
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Egg
masses of
the wood
frog—
Many
more
produced
than
can
survive
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• Variation among individuals
– Result of different varieties of
genes that code each
characteristic
– Ultimate source of variation is
random mutation
• Chemical or physical changes in
DNA that can be inherited
• Modifies genes
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• Every cell of an organism
requires nutrients
• Certain nutrients are used as
fuel for cellular respiration
• Virtually all cells carry on
cellular respiration
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• A self-sufficient ecosystem
contains three types of
organisms
– Producers
– Consumers
– Decomposers
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• Ecosystems depend on
continuous input of energy
• Organisms can neither create
energy nor use it with complete
efficiency
• During every energy
transaction, some is lost to the
environment as heat
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Energy
Flow in an
ecosystem
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• The scientific method involves
systematic thought
– Deductive reasoning draws
conclusions from premises
– Inductive reasoning begins
with observations and draws
conclusions or extrapolates
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The scientific
method involves
ordered steps:
– Observation
– Hypothesis
– Experimentation
(data)
– Conclusion
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