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CHAPTER 1
Life: Biological Principles and the Science of Zoology
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Zoology:
The scientific study of animal life
Does Life Have Defining Properties?
No simple definition
The history of life shows extensive
and ongoing change called
evolution
The Uses of Principles
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General Properties of Living Systems
Chemical Uniqueness:
Living systems demonstrate a unique and complex molecular organization
Small molecules are assembled into macromolecules:
1. Nucleic Acids
2. Proteins
3. Carbohydrates
4. Lipids
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General Properties of Living Systems
Complexity and Hierarchical Organization:
Living systems demonstrate a unique and complex hierarchical organization
In living systems there exists a hierarchy of levels that includes:
Macromolecules
Cells
Organisms
Populations
Species
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General Properties of Living Systems
Reproduction:
Living systems can reproduce themselves At each level of the biological hierarchy
living forms reproduce to generate others like themselves:
Genes replicated to produce new genes.
Cells divide producing new cells.
Organisms reproduce, sexually or asexually, to produce new organisms
Populations may fragment to produce new populations
Species may split to produce new species
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General Properties of Living Systems
Possession of a Genetic Program:
A genetic program provides fidelity of inheritance
Nucleic Acids: Polymers built of repeated units called nucleotides
DNA: Long, linear, chain of nucleotides containing genetic information
Sequence of nucleotide bases in DNA determines the order of amino acids in proteins
Genetic Code: correspondence between base sequences in DNA and the sequence of amino acids in a protein
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General Properties of Living Systems
Metabolism:
Living organisms maintain themselves
by acquiring nutrients from their
environments
Metabolic processes include:
Digestion
Energy production (Respiration)
Synthesis of required molecules and
structures by organisms
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General Properties of Living Systems
Metabolism is often viewed as an
interaction of destructive (catabolic)
and constructive (anabolic) reactions
Ex. Anabolic: formation of carbohydrates,
lipids, nucleic acids & proteins.
Ex. Catabolic: breaking of chemical
bonds to release stored energy.
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General Properties of Living Systems
Development:
All organisms pass through a
characteristic life cycle
Development describes the characteristic
changes that an organism undergoes from
its origin to its final adult form
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General Properties of Living Systems
Environmental Interaction:
All animals interact with their
environments
Ecology: The study of organismal
interaction with an environment
All organisms respond to environmental
stimuli, a property called irritability
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General Properties of Living Systems
Movement:
Living systems and their parts show precise and controlled movements arising from within the system
Living systems extract energy from their environments permitting the initiation of controlled movements
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General Properties of Living Systems
Movements at the cellular level are required for:
Reproduction
Growth
Responses to stimuli
Development in multicellular organisms
On a larger scale:
Entire populations or species may disperse from one geographic location to another over time
Movement of nonliving matter: Not precisely controlled by the moving objects
Often involves external forces
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Life Obeys Physical Laws
First Law of Thermodynamics (Law of
Conservation of energy):
Energy is neither created nor destroyed
but can be transformed from one form
to another
All aspects of life require energy and its
transformation
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Life Obeys Physical Laws
Second Law of Thermodynamics
Physical systems tend to proceed toward a state of greater disorder or entropy
The ultimate fate of materials in cells is degradation and dissipation of their chemical bond energy as heat
Organismal complexity is achieved and maintained only by the constant use and dissipation of energy flowing into the biosphere from the sun
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Life Obeys Physical Laws
The complex molecular organization in
living cells is attained and maintained only
as long as energy fuels the organization
Survival, growth, and reproduction of
animals require energy that comes from
breaking complex food molecules into
simple organic waste
