Generalidades de los fenómenos biológicos

Scientific Concepts, Discoveries, and Nature Phenomena Presented

Scope and course framing

• Biology is defined as the study of life, with emphasis on the generalities of biological phenomena (Unit 1).
• Later focus will emphasize cell biology and the characteristics of living beings.

Composition and organization of matter (levels of biological organization)

• Matter: anything that has mass and occupies space.
• Origin of the universe: matter is stated to have originated shortly after the Big Bang.
• Big Bang theory: the universe begins about 13.8 billion years ago as extremely hot, dense, and tiny; it then expands and cools.

Atoms and subatomic structure

• Matter consists of atoms (the units of chemical elements).
• Atom structure:
  • Protons and neutrons in the nucleus
  • Electrons in a surrounding electron cloud

Stepwise organization levels

• Subatomic level → atoms → molecules → macromolecules → organelles (subcellular structures) → cells → tissues → organs → systems → individuals → populations → communities → ecosystems → biosphere

Macromolecules and cellular structures

Molecules

• Example: water is formed by 2 hydrogen atoms + 1 oxygen atom.

Macromolecules (examples)

• Proteins
• Nucleic acids (e.g., double-stranded DNA)
• Lipids (e.g., phospholipid)
• Carbohydrates (e.g., glucose)

Organelles (examples)

• Mitochondria
• Chloroplasts
• Golgi complex (spelled “Golsi” in the original text)
• Endoplasmic reticulum

Cell theory and cell types

• Cells are formed by organelles enclosed within a membrane.

Eukaryotic vs. prokaryotic cells

• Eukaryotic cells: DNA enclosed by a nuclear envelope.
• Prokaryotic cells: DNA is not surrounded by a membrane (no nuclear envelope).

Emergent properties (key methodology/concept)

Emergent property: a trait that appears at a certain organization level, not present at lower levels, and cannot be predicted just from the components alone.

• Example: Hydrogen + oxygen atoms alone are gaseous, but in water molecules they form a liquid → liquid state is an emergent property.
• Example: Organelles are not “alive” by themselves; life emerges at the cellular level.
• Example: A brain can process information that an isolated neuron cannot → information processing as an emergent property.

Cell types in the human body (examples of specialization)

• Neurons
• Leukocytes (white blood cells) — immune system cells
• Enterocytes — intestinal cells
• Hepatocytes — liver cells

Cell theory (explicit statements)

• Organisms are composed of one or more cells.
• Reactions (energy-releasing and biosynthetic) occur within cells.
• All cells arise from pre-existing cells.
• Cells contain hereditary information, passed from parent cells to daughter cells.

Characteristics of living things (traits)

Core traits listed include:

• Made of one or more cells
• Different organization/complexity and proportions of elements despite sharing basic elements
• Anabolic and catabolic processes → metabolism
• Open systems exchange matter and energy with the environment
• Homeostasis: maintaining stable internal conditions within limits
• Irritability: reacting to internal/external stimuli
• Reproduction: perpetuation and transmission of information to offspring
• Growth: increasing size through development-related changes in form/function
• Evolution: variations provide raw material for evolution (variations occur despite reproduction fidelity)
• Autopoiesis: ability to regenerate components (e.g., a cell produces molecules to rebuild enzymes, membranes, and genetic material)

Classification of living things (taxonomy framework)

Decision traits used

• Number of cells: unicellular vs multicellular
• Genetic material location:
  • Prokaryotes (no membrane)
  • Eukaryotes (nuclear envelope present)
• Nutrition:
  • Autotrophs: make complex molecules from simple ones using energy
  • Heterotrophs: obtain complex molecules from the environment

Taxonomy

• Discipline that establishes rules for classification and nomenclature of organisms.

Binomial nomenclature (attributed to Carl Linnaeus)

• Scientific name has two parts: genus + species
• Formatting convention:
  • italics
  • only the genus initial capitalized
• Examples:
  • Homo sapiens
  • Mus musculus (spelled “Mus Musculus” in subtitles)
  • Pseudomonas aeruginosa

Taxonomic hierarchy and domains/kingdoms

Taxonomic hierarchy (eight levels)

• Domain, Kingdom, Phylum/Division, Class, Order, Family, Genus, Species

Three major domains

• Proposed in 1990 (attributed in subtitles to “Carl W”)
  • Bacteria
  • Archaea
  • Eukarya

Domain characteristics (summary)

• Bacteria: unicellular, prokaryotic; can be autotrophic or heterotrophic
• Archaea: unicellular, prokaryotic; genetically/biochemically distinct from bacteria; can be autotrophic or heterotrophic
• Eukarya: unicellular and multicellular; eukaryotic cells; includes autotrophs (plants) and heterotrophs (animals)

Five kingdoms (as presented)

• Monera: includes Bacteria + Archaea (unicellular, prokaryotic; autotrophic or heterotrophic)
• Protista: unicellular and multicellular; eukaryotic; autotrophic or heterotrophic
• Fungi: unicellular and multicellular; eukaryotic; heterotrophs
• Plantae: multicellular; eukaryotic; autotrophic
• Animalia: multicellular; eukaryotic; heterotrophic

Example of full classification (domestic dog)

• Domain: Eukarya
• Kingdom: Animalia
• Phylum: Chordata (animals with vertebral column)
• Class: Mammalia (milk-producing mammals)
• Order: Carnivora (mostly meat-based diet)
• Family: Canidae
• Genus: Canis
• Species: lupus

Researchers or Sources Featured (as named in subtitles)

• Emilia Castañaro (course instructor/professor)
• Carl Bon Linet / Carl W (presented as the taxonomist behind binomial nomenclature and the domain concept; corresponds to Carl Linnaeus and a 1990 domain proposal, likely to Woese though not explicitly stated correctly)
• A bibliography is mentioned, but no additional specific sources are named.