Chapter: Classification – Domain Eukarya and Taxonomic Hierarchy

Future Focus Science Academy, Athara Hazari

domain eukarya,classification,taxonomic hierarchy

Taxanomic Heirarchy

https://en.wikipedia.org/

1. Domain Eukarya

The Domain Eukarya includes all organisms with eukaryotic cells, which are distinct from prokaryotic cells of Bacteria and Archaea.

General Characteristics of Domain Eukarya

· Cells are eukaryotic – contain a true nucleus enclosed by a nuclear membrane.

· Possess membrane-bound organelles: Mitochondria, Chloroplasts (in plants and algae), Endoplasmic reticulum, Golgi apparatus, Lysosomes, Peroxisomes.

· Cytoskeleton present – a complex network of microtubules, microfilaments, and intermediate filaments providing structural support, intracellular transport, and movement.

· DNA is arranged in multiple linear chromosomes inside the nucleus, associated with histone proteins.

· Most eukaryotes reproduce sexually (via meiosis and fertilization) and asexually (via mitosis).

· Multicellular eukaryotes show cell differentiation with specialized tissues and organs.

· Eukaryotes evolved through endosymbiosis – mitochondria and chloroplasts originated from engulfed prokaryotes.

1.2 Taxonomic Hierarchy

A hierarchical system used to classify living organisms. Each level is called a taxon (plural: taxa).

Main Taxonomic Levels:

· Domain – Highest rank (e.g., Archaea, Bacteria, Eukarya)

· Kingdom – Groups organisms with fundamental characteristics

· Phylum – Groups organisms with similar body plans

· Class – More specific traits

· Order – Based on additional features

· Family – Closely related organisms

· Genus – Very closely related species

· Species – Basic unit of classification

Example: Taxonomic Rank Comparison

Taxonomic Rank	Human (Homo sapiens)	Sparrow (Passer domesticus)	Onion (Allium cepa)
Domain	Eukarya	Eukarya	Eukarya
Kingdom	Animalia	Animalia	Plantae
Phylum	Chordata	Chordata	Angiosperms
Class	Mammalia	Aves	Monocots
Order	Primates	Passeriformes	Asparagales
Family	Hominidae	Passeridae	Amaryllidaceae
Genus	Homo	Passer	Allium
Species	Homo sapiens	Passer domesticus	Allium cepa