5- Biología celular. Clasificación de los seres vivos

Introduction to Biological Classification

Overview of Living Organisms

• The session begins with a focus on the classification criteria for living organisms, building on previous discussions about their defining properties.

• Different criteria are introduced for classifying the vast diversity of known living beings.

Cellular Composition

• Organisms can be classified based on cell number: unicellular (single-celled) and multicellular (composed of multiple cells).

• Examples of unicellular organisms include protozoa and bacteria, while multicellular examples encompass plants and animals.

Presence of True Nucleus

• Classification also considers the presence or absence of a true nucleus; organisms with a defined nucleus are termed eukaryotic.

• Eukaryotic examples include animals, plants, and protozoa; prokaryotic organisms, lacking a true nucleus, include bacteria.

Nutritional Modes in Organisms

Autotrophs vs. Heterotrophs

• Organisms are further classified by their nutritional methods: autotrophs synthesize their own food, while heterotrophs rely on other sources.

• Plants exemplify autotrophic organisms through photosynthesis, producing carbohydrates for nourishment.

Taxonomy as a Science

Hierarchical Classification System

• Taxonomy is established as a scientific discipline aimed at grouping living beings based on shared characteristics in a hierarchical manner.

• There are eight taxonomic categories recognized today: domain, kingdom, phylum/division, class, order, family, genus, and species.

Definition of Species

• A species is defined as a group of organisms sharing common physiological and morphological traits that can interbreed to produce fertile offspring.

The Five Kingdom Classification System

Overview of the Five Kingdoms

• The five kingdoms currently recognized are Monera (bacteria), Protista (unicellular and multicellular eukaryotes), Fungi (mushrooms), Plantae (plants), and Animalia (animals).

Characteristics of Each Kingdom

• Monera: Comprises unicellular prokaryotes; some are autotrophic while others are heterotrophic.

• Protista: Includes both unicellular and multicellular eukaryotes that cannot produce their own food.

• Fungi: Encompasses both unicellular and multicellular eukaryotic fungi.

• Plantae: Consists mainly of multicellular eukaryotic plants that are autotrophic.