The Smallest Unit of Life is a Cell -...
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The Science of Biology Properties of Life ! Life’s basic characteristic is a high degree of order Levels of Biological Organization Ecosystems The biosphere Organisms Populations Communities Cells Organelles Molecules Tissues Organs and organ systems Cell 1 !m Atoms 10 !m 50 !m Each level of biological organization has emergent properties The Smallest Unit of Life is a Cell ! The cell is the lowest level of organization that can perform all activities of life ! The ability of cells to divide is the basis of all reproduction, growth, and repair of multicellular organisms
Transcript of The Smallest Unit of Life is a Cell -...
The Science of Biology
Properties of Life
! Life’s basic characteristic is a high degree of order
Levels of Biological Organization
Ecosystems!
The biosphere!
Organisms!
Populations!
Communities!
Cells!
Organelles!
Molecules!Tissues!
Organs and organ systems!
Cell!1 !m!
Atoms!
10 !m!
50 !m!
Each level of biological organization has emergent properties
The Smallest Unit of Life is a Cell
! The cell is the lowest level of organization that can perform all activities of life
! The ability of cells to divide is the basis of all reproduction, growth, and repair of multicellular organisms
! Cell theory • All organisms composed of cells • Cells are life’s basic units • All cells come from preexisting cells
! Molecular basis of inheritance is DNA
! Structure fits function
! Diversity of life arises by evolution
Unifying Themes in Biology Energy Flow through an Ecosystem
Sun!
Inflow of
light energy
Loss of
heat energy
Air
Chemical energy
Cycling of chemical nutrients Producers Consumers
Decomposers
Soil Ecosystem
H2O
O2 CO2 CO2
Producers (plants and other photosynthetic
organisms) Consumers
(including animals)!
Two basic types of cells: Prokaryotes and Eukaryotes
All Cells - are enclosed by a membrane - use DNA as genetic information - contain ribosomes
- Prokaryotes (bacteria and archaea) do not contain a nucleus - Eukaryotes contain a nucleus
Diversity of Life:
Living Things are categorized into
3 Domains : Eukarya
Archaea
Bacteria Within the Domain of the Eukarya, we distinguish 4 kingdoms:
Plantae
Fungi
Animalia
Protista
! Scientists use a systematic approach to gain understanding of the natural world
• Observation • Hypothesis formation • Prediction • Experimentation • Conclusion
Observation
Question
Hypothesis # 1: Dead batteries
Hypothesis # 2: Burnt-out bulb
Prediction: Replacing batteries will fix problem
Prediction: Replacing bulb will fix problem
Test prediction Test prediction
Test falsifies hypothesis Test does not falsify hypothesis
The Scientific Method Hypothesis-based Inquiry
An Example of Scientific Inquiry: Darwin and Evolution
He published “On the Origin of Species by Natural Selection” in 1859 12
! Darwin saw that characteristics of similar species varied from place to place
! He suggested that species today come from a succession of ancestors and evolve by adaptation and natural selection
The Predictions of Natural Selection have been tested
• Molecular Evidence • Compare genomes
or proteins of different organisms
• Phylogenetic trees – based on tracing origin of particular nucleotide changes to reconstruct an evolutionary history
