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Hierarchy of Life
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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Chapter 1
An Introduction to Biology
1.1 Principles of Biology and the Levels of Biological Organization
1.2 Unity and Diversity of Life
Key Concepts:
1. Cells are the simplest units of life
2. Living organisms use energy
3. Living organisms interact with their environment
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1.1 Principles of Biology
Biology: the scientific study of living things.
4. Living organisms maintain homeostasis
5. Living organisms grow and develop
6. The genetic material provides a blueprint for reproduction
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Principles of Biology
7. Populations of organisms evolve from one generation to the next
8. All species (past and present) are related by an evolutionary history
9. Structure determines function
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Principles of Biology
10. New properties of life emerge from complex interactions
11. Biology is an experimental science
12. Biology affects our society
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Principles of Biology
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Levels of Biological Organization
1 2
3
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6
7
89
AtomsMolecules andmacromolecules
Cells
TissuesOrgans
Organism
Population
Community
Biosphere
Ecosystem
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1.2 Unity and Diversity of Life
Unity All life displays a common set of characteristics United by a shared evolutionary history
Diversity Life has a diversity of form in diverse environments
Evolutionary History
Life began on Earth as primitive cells between3.5 - 4 billion years ago (bya)
Those primitive cells underwent evolutionary changes to give rise to the species of today
Evolutionary history helps us understand the structure and function of an organism
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Evolutionary change involves modifications of pre-existing characteristics
Structures may be modified to serve new purposes
Example:
Walking limbswere modified into a dolphin’s flipper or a bat’s wing
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Two Mechanisms of Evolutionary Change
1. Vertical descent with modification Progression of changes in a lineage New species evolve from pre-existing species by
the accumulation of mutations Natural selection takes advantage of beneficial
mutations
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12
0
5
Mil
lio
ns
of
yea
rs a
go
(m
ya
)
20
40
55
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Equus
StyohipparionNeohipparionHipparion
Nannippus
Hippidium andother genera
Pliohippus
Calippus
Merychippus
Archaeohippus
Hypohippus
MegahippusSinohippus
Anchitherium
Parahippus
Epihippus
Miohippus
Mesohippus
Paleotherium
Propalaeotherium
Pachynolophus Orohippus
Hyracotherium
Vertical Evolution: The Horse Lineage
2. Horizontal gene transfer Genetic exchange between different species Relatively rare Genes that confer antibiotic resistance are
sometimes transferred between different bacteria species
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Antibiotic-resistancegene
DNA DNA
Antibiotic-resistancegene fromE. coli
Bacterial species such asStreptococcus pneumoniae
Bacterial species such asEscherichia coli
Horizontalgenetransfer toanotherspecies
Horizontal Gene Transfer: Antibiotic Resistance
Tree or web of life?
Horizontal gene transfer was an important part of the process that gave rise to modern species
Tree of life focuses on vertical evolution The tree of life is predictive Placement of a new species on the tree of life
immediately informs us about its biology Understanding relationships among species allows
biologists to make predictions about species that have not yet been studied
Web of life includes the contribution of horizontal gene transfer
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KEYVertical evolutionHorizontal gene transfer
Common ancestral community of primitive cells
Bacteria Archaea
Fungi Animals
Eukarya
Plants Protists
Web of Life: Vertical Evolution and Horizontal Gene Transfer
Classification
Taxonomy is the grouping of species based on common ancestry
Three domains of life Bacteria - unicellular prokaryote Archaea - unicellular prokaryote Eukarya - unicellular and multicellular eukaryotes
Complex cells with a nucleus and organelles Four kingdoms:
Protista, Plantae, Fungi, and Animalia
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Domain Bacteria: Mostly unicellular prokaryotes that
inhabit many diverse environments on Earth
© Dr. David M. Phillips/Visuals Unlimited
Domain Archaea: Unicellular prokaryotes
that often live in extreme environments,
such as hot springs
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Domain Eukarya: Unicellular and multicellular organisms having cells with internal compartments that serve various functions
Protists
1: © Dr. Dennis Kunkel/ Visuals Unlimited; 2: © Kent Foster/Photo Researchers; 3: © Carl Schmidt-uchs/Photo Researchers; 4: © Fritz Polking/Visuals Unlimited
Plants
Fungi Animals
A species is placed into progressively smaller groups that are more closely related
Emphasizes the unity and diversity of different species
Example: Clownfish
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Classification
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Examples
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Eukarya
Animalia
Chordata
Actinopterygii
Perciformes
Pomacentridae
Amphiprion
ocellaris
2,000 mya
600 mya
525 mya
420 mya
80 mya
~ 40 mya
~ 9 mya
> 3 mya
> 5,000,000
> 1,000,000
50,000
30,000
7,000
360
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Taxonomicgroup
Clownanemonefishis found in
Approximate timewhen the commonancestor for thisgroup arose
Approximatenumber ofmodern speciesin this group
Binomial nomenclature Each species has a unique scientific name Genus name capitalized Species descriptor is not capitalized Both names are italicized
Amphiprion ocellaris = Clownfish
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Genomes and Proteomes
Genome - the complete genetic makeup of an organism Genomics - techniques used to analyze DNA sequences
Comparison of genomes of different species Proteome - the complete complement of proteins of
an organism Proteomics - Comparison of proteomes of different species
Techniques used to analyze the proteins of a species The study of genomes and proteomes provides an
evolutionary foundation for our understanding of biology Fundamental to understanding an organisms characteristics
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Transport proteins:Proteins facilitate theuptake and export ofsubstances
Cell organization:Proteins organize thecomponents withincells
Extracellularproteins:Proteins hold cellstogether in tissues
Cytoskeleton:Proteins are involvedin cell shape andmovement
In eukaryotes, most of the genomeis contained within chromosomesthat are located in the cell nucleus
Cell signaling:Proteins are neededfor cell signaling withother cells and withthe environment
Enzymes:Proteins function asenzymes to synthesizeand break downcellular molecules andmacromolecules
(a) The genome
Extracellular fluid(b) The proteome
Most genes encode mRNAsthat contain the informationto make proteins
Cytoplasm Chromosome
Sets ofchromosomes
Nucleus
DNAChromosome
Sets ofchromosomes
Nucleus
Gene