Biological Organization & Cell Structure

Levels of Biological Organization

Living matter is organized into distinct levels, categorized as abiotic or biotic:

• Abiotic: Components that do not conform to living matter, such as inert substances.
• Biotic: Components exclusive to living organisms.

Hierarchy of Living Matter

• Subatomic: Particles and atoms.
• Atom: The smallest portion of a chemical element.
• Molecular: Molecules formed by the joining of two or more atoms.
• Macromolecules: Resulting from the binding of many molecules to form a polymer.
• Supramolecular Complexes: Aggregations of macromolecules.
• Subcellular Structures: Union of different supramolecular complexes, resulting in the cell's structure with characteristic functions.
• Cells: Comprised of various organelles and structures. (Biotic Level)
• Tissue: A group of similar cells that act in concert.
• Systems and Organs: Organs that perform a specific function.
• Individual: Composed of various systems and organs.
• Population: A group of individuals of the same species.
• Community or Biocenosis: A set of distinct populations that share the same space and establish relationships.
• Ecosystems: A level consisting of several communities interacting with their abiotic environment.
• Ecosphere: The collection of all ecosystems on Earth.

Cell Specialization

• Tissue: Associated cells that specialize in specific functions and can no longer live isolated from the body.
• Colonies: Cells associated for better efficacy but do not reach the tissue level; each cell may perform any function independently.

The Cell: Fundamental Unit of Life

The cell is the morphological and functional unit of all living things, i.e., the simplest form of living matter capable, by itself, of performing all basic functions of a living being.

• Unicellular: Organisms composed of a single cell.
• Multicellular: Organisms composed of millions of cells.

Common Cell Structures

• Plasma Membrane: A thin sheet covering the cell, regulating the passage of substances.
• Cytoplasm: The internal fluid environment of the cell, containing organelles.
• Genetic Material: Molecules of DNA that control cell function and heredity.

Types of Cells by Complexity and Organization

• Prokaryotes: Small cells of simple organization, lacking a true nucleus. Their DNA is free in the cytoplasm.
• Eukaryotes: Cells with a true nucleus where the DNA is contained, and a more complex organization due to the existence of organelles that carry out different functions.

Eukaryotic Cell Models

• Animal Cell: Lacks a cell wall and chloroplasts; possesses centrioles and smaller vacuoles (when present).
• Plant Cell: Possesses chloroplasts, large central vacuoles, and a cell wall that maintains its polyhedral shape.