Foundations of General Biology: Organization, Evolution, and Diversity of Life

Organization and Structure in Biology

Levels of Biological Organization

Biological systems are organized in a hierarchical manner, where each level builds upon the previous one. This organization allows for the emergence of complex functions and properties.

• Biosphere: All life on planet Earth, including water, land, and atmosphere.

• Ecosystem: Living and nonliving things in a particular area.

• Community: Specific organisms/species in an ecosystem, set of populations that inhabit a certain area.

• Population: All individuals of one type of species.

• Organism: Individual living thing; actions of organisms are based on cell functions.

• Organ: Consists of multiple tissues performing a function for an organism.

• Tissue: Group of similar cells that perform a function.

• Cell: Fundamental unit of life, encased by a membrane.

• Organelle: Functional component within cells.

• Molecule: Consists of more than one atom.

Emergent Properties: New properties arise at each level of organization due to the arrangement and interactions of parts.

Cell Types

• Eukaryotic Cells: Organelles enclosed in a membrane, contain a nucleus.

• Prokaryotic Cells: Lack a nucleus, do not have membrane-enclosed organelles, generally smaller than eukaryotic cells.

Structure and Function

There is a direct correlation between the structure of biological components and their function. For example, the shape of a bird's wing is adapted for flight.

Genetic Information and Molecular Biology

DNA and Genes

DNA (deoxyribonucleic acid) is the molecule that contains genetic material. It is organized into chromosomes, which contain hundreds or thousands of genes (sections of DNA transmitted from parents to offspring).

• DNA is made of two long chains called strands, resembling a double helix.

• Made up of nucleotides: A (adenine), T (thymine), C (cytosine), G (guanine). Genetic information is coded by the sequence of these nucleotides.

Genes are transcribed into RNA and then translated into proteins called amino acids. Cells use this information to synthesize proteins that perform cellular functions.

Information Flow, Energy, and Interactions

• Information: Genetics encoded in DNA.

• Energy and Matter: Flow from different parts of the environment and cycle through ecosystems.

• Interactions: Predator and prey relationships, symbiosis, and competition.

• Evolution: Natural selection and adaptation over long periods of time.

Life and Evolution

Diversity of Life: Domains and Kingdoms

Life is classified into three domains based on cellular characteristics:

• Bacteria

• Archaea

• Eukaryota: Includes humans and all organisms with a nucleus.

Eukaryotes are further divided into kingdoms:

• Kingdom Plantae: Plants

• Kingdom Fungi: Mushrooms, fungus

• Kingdom Animalia: Animals

• Protists: Eukaryotes that are not plants, fungi, or animals; very diverse, not considered a kingdom

Unity of Life: Homology vs. Analogy

All living things share similarities at the molecular level, such as the use of DNA and RNA. Homology and analogy are important concepts in understanding evolutionary relationships.

• Homology: Similar bone patterns across animals due to shared ancestry; traits passed down from a common ancestor.

• Analogy: Similar function but not due to common ancestry; evolved independently.

Descent with Modification: Evolution at its core, as described by Charles Darwin. Traits are passed down and inherited, leading to the formation of new species.

Evolutionary Theory and Evidence

Charles Darwin's Ideas

• Organisms are well adapted to live in their environments.

• There are multiple shared characteristics of life.

• Life is rich and diverse.

• Species accumulate differences from their ancestors as they adapt to their environments over time.

Descent with modification leads to shared ancestry and diversity of life on Earth.

Fossil Evidence and Geological Theories

• Fossils: Remains and traces of organisms from the past, found in sedimentary rocks.

• Strata: Layers in sedimentary rock; reveal when organisms may have lived.

• Paleontology: Study of fossils.

• Hutton and Lyell: Proposed that geological features are shaped by gradual changes over long periods.

• Lamarck: Hypothesized that acquired characteristics could be inherited (now disproven).

Darwin's Observations and Natural Selection

• Studied finches and mockingbirds in the Galapagos; observed adaptations and speciation.

• Adaptations: Inherited characteristics that increase survival and reproduction.

• Natural Selection: Individuals with favorable traits reproduce more, leading to evolution.

Artificial Selection

• Selective breeding of organisms to enhance desired traits.

• Can occur over short periods of time.

• Example: Penicillin resistance in bacteria due to evolution.

Homology, Analogy, and Evolutionary Relationships

Homology and Vestigial Structures

• Homology: Similar traits due to common ancestry; represented in skeletons of different animals.

• Vestigial Structures: Remnants of features that functioned in ancestors.

Convergent Evolution and Biogeography

• Convergent Evolution: Independent evolution of similar features in different lineages.

• Biogeography: Study of geographic distribution of species; explained by continental drift and evolution.

• Endemic Species: Specific to certain locations, such as islands.

Patterns and Processes of Evolution

• Pattern: Observation that life has evolved over time.

• Process: Mechanisms of evolution, such as natural selection.

• Theory: More comprehensive than a hypothesis; explains a variety of phenomena.

Taxonomy and Phylogenetics

Linnaean Classification and Binomial Nomenclature

• Binomial Nomenclature: Two-part scientific naming system (genus + species).

• Organizes species into hierarchical categories: kingdom, phylum, class, order, family, genus, species.

Phylogenetic Trees

• Visualize hypothesized evolutionary relationships.

• Branch points (nodes) represent speciation events.

• Clades share recent common ancestors.

• Homologous and analogous traits are used to interpret evolutionary history.

Chemistry of Life

Elements and Atoms

• Elements: Substances that cannot be broken down further; essential elements for life include carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.

• Atoms: Consist of protons (positive), neutrons (neutral), and electrons (negative).

• Valence Electrons: Electrons in the outer shell; determine chemical reactivity.

Chemical Bonds

• Covalent Bonds: Atoms share electrons; can be single, double, or triple bonds.

• Ionic Bonds: Complete transfer of electrons; creates charged ions.

• Hydrogen Bonds: Weak bonds, important for water properties and biological molecules.

• Nonpolar Covalent Bonds: Electrons shared equally.

• Polar Covalent Bonds: Electrons shared unequally, creating partial charges.

Water and Its Properties

• Hydrogen bonds between water molecules explain cohesion, adhesion, and surface tension.

• Water is essential for life due to its solvent properties and role in chemical reactions.

Organic Molecules and Macromolecules

Carbohydrates

• Monosaccharides: Simple sugars (e.g., glucose).

• Disaccharides: Two monosaccharides joined together (e.g., sucrose).

• Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).

• Glycosidic Linkage: Bond between monosaccharides.

Lipids

• Fatty Acids: Long hydrocarbon chains; can be saturated (no double bonds) or unsaturated (one or more double bonds).

• Triglycerides: Three fatty acids linked to glycerol; energy storage.

• Phospholipids: Two fatty acids and a phosphate group; major component of cell membranes.

• Steroids: Lipids with a four-ring structure.

Proteins and Nucleic Acids

• Proteins: Polymers of amino acids; perform a wide range of functions.

• Nucleic Acids: DNA and RNA; store and transmit genetic information.

Key Table: Domains and Kingdoms of Life

Domain	Kingdoms/Groups	Main Features
Bacteria	None (prokaryotes)	No nucleus, unicellular
Archaea	None (prokaryotes)	No nucleus, unicellular, often extremophiles
Eukaryota	Plantae, Fungi, Animalia, Protists	Nucleus present, multicellular or unicellular

Key Equations and Concepts

• General Chemical Reaction:

$\text{Reactants} \rightarrow \text{Products}$

• Photosynthesis:

$6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2$

• Cellular Respiration:

$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy}$

• Darwin's Theory of Evolution by Natural Selection:

$\text{Variation} + \text{Inheritance} + \text{Differential Survival} \rightarrow \text{Evolution}$

Additional info: Some explanations and examples have been expanded for clarity and completeness, including the chemical equations and the table summarizing domains and kingdoms.