Biology 101 Notes

Introduction to Biology

  • Biology term breakdown:

  • Bios: means life

  • Logos: means study

  • Definition: Biology is the study of life, involving living organisms, their environments, and their interactions.

Characteristics of Life

  • Cells: Made of one or more cells

  • Stimuli Response: Can sense and respond to environmental changes through receptors detecting stimuli

  • Homeostasis: Maintains stable internal environment (e.g., blood sugar regulation by pancreas)

  • Organization: Structured organization from atom to biosphere:

  • Levels:

    • Atom (Hydrogen)

    • Molecule (Water)

    • Organelle (Nucleus)

    • Cell (Neuron)

    • Tissue (Nervous Tissue)

    • Organ (Brain)

    • Organ System (Nervous System)

    • Organism (e.g., Sea Lion)

    • Population (Colony)

    • Community (e.g., Giant kelp forest)

    • Ecosystem

    • Biosphere (Earth)

  • Metabolism: Set of reactions in cells to grow, survive, reproduce, and develop

  • Growth and Development: Involves adding mass and undergoing changes throughout life.

  • Reproduction: Producing offspring is essential for species continuation.

  • Evolution: Adaptive genetic changes occur over time.

Interdependencies Among Organisms

  • Ecosystem Interaction: Study of living and nonliving interactions

  • Community Members:

  • Producers: Make their own food

  • Consumers: Obtain energy from other organisms

  • Decomposers: Break down wastes and remains

  • Food Web: Represents energy transfer from producers to consumers; all energy originates from the sun.

Habitat and Niche

  • Habitat: Organism's home, provides food, water, shelter, and space

  • Niche: Role of an organism in its environment; cannot share identical niches.

Energy Flow in Ecosystems

  • Begins with solar energy

  • Flows in one direction through organisms

  • Eventually returns to the environment

Natural Selection and Adaptation

  • Adaptive Traits: Traits that enhance survival/reproduction (e.g., hummingbirds’ long bills, zebra stripes).

  • Natural Selection: Results in organisms adapting to their environment through selective reproductive changes; gene frequency remains constant unless disrupted.

Mutations

  • Definition: Changes in DNA sequences

  • Causes: Errors in replication, exposure to mutagens (e.g., radiation), can be random or environmentally harmful.

  • Examples: Breeding for desirable traits in livestock or crops, accidental mutations resulting in new traits.

Antibiotic Resistance and Natural Selection

  • Phenomena: Resistance arises through mutations in bacterial populations, leading to survival and reproduction of resistant bacteria over time.

Artificial Selection

  • Definition: Human-facilitated selective breeding to promote specific traits within populations.

Classification of Life

  • Three-Domain System: Developed by Woese et al. in 1990:

  • Archaea: Prokaryotic, ancient organisms (e.g., methanogens, halophiles)

  • Bacteria: Prokaryotic, first discovered bacteria

  • Eukarya: Eukaryotic organisms with membrane-bound nuclei, including plants, animals, and fungi.

Taxonomy

  • Definition: The science of classifying and organizing living organisms based on their evolutionary relationships, morphology, and genetics.

  • Hierarchy:

  • Domain

  • Kingdom

  • Phylum

  • Class

  • Order

  • Family

  • Genus

  • Species

  • Binomial Nomenclature: Two-part Latin naming system for species.

Scientific Naming Rules (Binomial Nomenclature)

  • Components: Genus (capitalized) + species (lowercase)

  • Formatting: Italicized or underlined

  • Authorship: May include author in parentheses

  • Abbreviation: Genus name can be abbreviated after first use (e.g., E. coli).

  • Uniformity: Ensures clarity across languages and communicates evolutionary relations.

Classification vs. Binomial Nomenclature

  • Classification: Arrangement based on similarities and differences (8 levels)

  • Binomial Nomenclature: Specific naming of organisms using genus and species names, ensuring unique identification.