BackFoundations of General Biology: Organization, Evolution, and Diversity of Life
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Organization of Life
Levels of Biological Organization
The structure and function of living organisms are organized hierarchically, from molecules to the biosphere. Each level builds upon the previous, with increasing complexity and emergent properties.
Biosphere: All life on Earth, including water, land, and atmosphere.
Ecosystem: All living and nonliving things in a particular area.
Community: Specific organisms/species in an ecosystem, set of populations inhabiting a certain area.
Population: All individuals of one species in an area.
Organism: An individual living thing; actions are based on cell and organ function.
Organ: Composed of multiple tissues performing a function.
Tissue: Group of cells performing a specific function.
Cell: Fundamental unit of life, enclosed by a membrane.
Eukaryotic cells: Organelles enclosed in a membrane, contain a nucleus.
Prokaryotic cells: Lack a nucleus, do not have membrane-enclosed organelles, and are smaller than eukaryotic cells.
Organelle: Functional components within cells.
Molecule: Composed of more than one atom.
Emergent Properties arise at each level of organization due to specific arrangements and interactions of components, which cannot be predicted by examining individual parts alone.
Structure and Function
There is a direct correlation between the structure and function in biological systems. For example, the shape of a bird's wing bone determines its flying ability.
Example: Hummingbirds have shorter humerus bones, allowing them to flap their wings in unique ways for hovering.
Genetic Information and Expression
DNA and Genes
DNA (deoxyribonucleic acid) is the molecule that contains genetic material. Chromosomes are structures made of DNA and proteins, containing thousands of genes, which are sections of DNA inherited from parents.
Gene Expression: The process by which information in DNA is transcribed into mRNA and then translated into proteins (amino acids), resulting in the synthesis of functional proteins.
Formula:
Information Flow
Genetic information is encoded in DNA and is essential for the development, function, and reproduction of organisms.
Energy, Matter, and Interactions
Energy and Matter
Energy flows and matter cycles through ecosystems, supporting life processes. The sun is the primary source of energy for most life on Earth.
Example: Carbon cycles through living organisms and the environment.
Interactions
Organisms interact with each other and their environment, such as predator-prey relationships, which influence ecosystem dynamics.
Evolution: The Unifying Theme of Biology
Definition and Importance
Evolution is the process by which species change over time through genetic variation and natural selection. It explains both the unity and diversity of life.
Descent with Modification: Species accumulate differences from their ancestors as they adapt to new environments.
Natural Selection: Individuals with advantageous traits are more likely to survive and reproduce, passing those traits to offspring.
Charles Darwin's Contributions
Darwin proposed that evolution occurs through descent with modification and natural selection, as described in his book On the Origin of Species by Means of Natural Selection.
Organisms are well adapted to their environments.
There are multiple shared characteristics of life.
Life is rich and diverse.
Mechanisms of Evolution
Adaptations: Inherited characteristics that increase survival and reproduction.
Artificial Selection: Selective breeding by humans to produce desired traits.
Homology: Similar traits resulting from common ancestry.
Convergent Evolution: Independent evolution of similar features in different lineages.
Analogous Structures: Features with similar function but not common ancestry.
Vestigial Structures: Remnants of features that served a function in ancestors.
Evidence for Evolution
Fossils: Remains and traces of organisms found in sedimentary rocks.
Strata: Layers of sediment that show the age of fossils.
Paleontology: The study of fossils.
Biogeography: Study of geographic distribution of species.
Endemic Species: Organisms specific to a certain location.
Classification and Diversity of Life
Domains and Kingdoms
Life is classified into three domains and several kingdoms based on cellular structure and genetic relationships.
Domain | Key Features | Kingdoms/Groups |
|---|---|---|
Bacteria | Prokaryotic, no nucleus | Various bacterial species |
Archaea | Prokaryotic, distinct from bacteria | Various archaeal species |
Eukaryota | Eukaryotic, nucleus present |
|
Biodiversity is the foundation of life on Earth, with an estimated 8 million species, though only 1.2 million eukaryotic species are known.
Taxonomy and Binomial Nomenclature
Taxonomy is the science of classifying organisms. Binomial nomenclature is the two-part naming system developed by Carl Linnaeus, using Latin names for genus and species.
First word (genus) is capitalized; second word (species) is lowercase.
Both names are italicized.
Example: Canis lupus (gray wolf)
Unity and Diversity of Life
Unity of Life
All living things share common features, such as the use of DNA and RNA, similar cellular structures, and homologous body parts.
Humans and other animals share similar immune cells and developmental patterns.
Appendix in some animals may not have a function, showing evolutionary remnants.
Diversity of Life
Despite shared ancestry, species vary greatly due to adaptation and modification over time.
Species accumulate differences as they adapt to their environments.
Shared ancestry leads to homologous structures, but function may differ.
Summary Table: Key Evolutionary Concepts
Concept | Definition | Example |
|---|---|---|
Natural Selection | Process by which individuals with favorable traits survive and reproduce | Antibiotic resistance in bacteria |
Artificial Selection | Selective breeding by humans | Dog breeds |
Homology | Similarity due to shared ancestry | Forelimb bones in mammals |
Convergent Evolution | Independent evolution of similar traits | Wings in bats and birds |
Analogous Structures | Similar function, different ancestry | Wings of insects and birds |
Vestigial Structures | Remnants of ancestral features | Human appendix |
Key Terms and Definitions
Emergent Properties: New characteristics that arise at each level of organization due to interactions among components.
Gene Expression: The process by which genetic information is used to produce proteins.
Adaptation: Inherited trait that increases an organism's chance of survival and reproduction.
Homology: Similarity in traits due to shared ancestry.
Convergent Evolution: Evolution of similar traits in unrelated lineages.
Analogous Structures: Traits with similar function but different evolutionary origins.
Vestigial Structures: Features that were functional in ancestors but are reduced or nonfunctional in descendants.
Biogeography: Study of the geographic distribution of species.
Endemic Species: Species found only in a specific geographic location.
Taxonomy: Science of classifying organisms.
Binomial Nomenclature: Two-part scientific naming system for species.
Additional info: Some explanations and examples have been expanded for clarity and completeness, including the summary tables and definitions.
