1. Hierarchy of Life
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2. Chapter 1 An Introduction to Biology
Key Concepts:
1.1 Principles of Biology and the Levels of Biological Organization
1.2 Unity and Diversity of Life

3. Biology: the scientific study of living things.
1.1 Principles of Biology
Biology: the scientific study of living things.
Cells are the simplest units of life
Living organisms use energy
Living organisms interact with their environment

4. Principles of Biology Living organisms maintain homeostasis
Living organisms grow and develop
The genetic material provides a blueprint for reproduction

5. Principles of Biology
Populations of organisms evolve from one generation to the next
All species (past and present) are related by an evolutionary history
Structure determines function

6. Principles of Biology
New properties of life emerge from complex interactions
Biology is an experimental science
Biology affects our society

7. Levels of Biological Organization1 2 3 4 5 6 7 8 9
Atoms
Molecules and
macromolecules
Cells
Tissues
Organs
Organism
Population
Community
Biosphere
Ecosystem 10

8. 1.2 Unity and Diversity of Life
All life displays a common set of characteristics
United by a shared evolutionary history
Diversity
Life has a diversity of form in diverse environments

9. Evolutionary History
Life began on Earth as primitive cells between 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

10. Evolutionary change involves modifications of pre-existing characteristics
Structures may be modified to serve new purposes
Example:
Walking limbs were modified into a dolphin’s flipper or a bat’s wing

11. Two Mechanisms of Evolutionary Change
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

12. Vertical Evolution: The Horse Lineage5
Millions of years ago (mya) 20 40 55 10
Equus
Styohipparion
Neohipparion
Hipparion
Nannippus
Hippidium and
other genera
Pliohippus
Calippus
Merychippus
Archaeohippus
Hypohippus
Megahippus
Sinohippus
Anchitherium
Parahippus
Epihippus
Miohippus
Mesohippus
Paleotherium
Propalaeotherium
Pachynolophus
Orohippus
Hyracotherium

13. Horizontal gene transfer
Genetic exchange between different species
Relatively rare
Genes that confer antibiotic resistance are sometimes transferred between different bacteria species

14. Horizontal Gene Transfer: Antibiotic Resistance
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Antibiotic- resistance
gene
DNA
Antibiotic-
resistance
gene from
E. coli
Bacterial species such as
Streptococcus pneumoniae
Escherichia coli
Horizontal
transfer to
another
species

15. 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

16. Web of Life: Vertical Evolution and Horizontal Gene Transfer
KEY
Vertical evolution
Horizontal gene transfer
Common ancestral community of primitive cells
Bacteria
Archaea
Fungi
Animals
Eukarya
Plants
Protists

17. 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

18. Domain Bacteria: Mostly unicellular prokaryotes that
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Domain Bacteria: Mostly unicellular prokaryotes that
inhabit many diverse environments on Earth
Domain Archaea: Unicellular prokaryotes that often live in extreme environments, such as hot springs
© Dr. David M. Phillips/Visuals Unlimited

19. Copyright © The McGraw-Hill Companies, Inc
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Protists
Plants
Fungi
Animals
1: © Dr. Dennis Kunkel/ Visuals Unlimited; 2: © Kent Foster/Photo Researchers; 3: © Carl Schmidt-uchs/Photo Researchers; 4: © Fritz Polking/Visuals Unlimited
Domain Eukarya: Unicellular and multicellular organisms having cells with internal compartments that serve various functions

20. Classification
A species is placed into progressively smaller groups that are more closely related
Emphasizes the unity and diversity of different species
Example:
Clownfish

21. 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 28 1
Taxonomic
group
Clown
anemonefish
is found in
Approximate time
when the common
ancestor for this
group arose
Approximate
number of
modern species
in this group

22. Binomial nomenclature
Each species has a unique scientific name
Genus name capitalized
Species descriptor is not capitalized
Both names are italicized
Amphiprion ocellaris = Clownfish

23. 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

24. In eukaryotes, most of the genome is contained within chromosomes
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In eukaryotes, most of the genome
is contained within chromosomes
that are located in the cell nucleus
Gene
(a) The genome
Most genes encode mRNAs
that contain the information
to make proteins
Cytoplasm
Chromosome
Chromosome
DNA
Sets of
chromosomes
Sets of
chromosomes
Cell signaling:
Proteins are needed
for cell signaling with
other cells and with
the environment
Nucleus
Nucleus
Cytoskeleton:
Proteins are involved
in cell shape and
movement
Cell organization:
Proteins organize the
components within
cells
Enzymes:
Proteins function as
enzymes to synthesize
and break down
cellular molecules and
macromolecules
Transport proteins:
Proteins facilitate the
uptake and export of
substances
Extracellular
proteins:
Proteins hold cells
together in tissues
Extracellular fluid
(b) The proteome