Kingdoms and Domains 18.3

Domain

• Most

inclusive

taxonomic

category; category;

larger than a

kingdom.

Bacteria• Domain of unicellular prokaryotes that

have cell walls containing peptidoglycan.

Eubacteria• Kingdom of unicellular prokaryotes whose

cell walls are made up of peptidoglycan.

Archaea

• Domain of unicellular prokaryotes that have

cell walls that do not contain peptidoglycan.

Archaebacteria

• Kingdom of unicellular prokaryotes whose

cell walls that do not contain peptidoglycan.

Eukarya• Domain of all organisms whose cells have

nuclei, including protists, plants, fungi, and

animals.

Protista

• Kingdom composed of eukaryotes that are not

classified as plants, animals, or fungi.

Fungi• Kingdom composed of heterotrophs; many

obtain energy and nutrients from dead

organic matter.

Plantae• Kingdom of multicellular photosynthetic

autotrophs that have cell walls containing

cellulose.

Animalia

• Kingdom of multicellular eukaryotic

heterotrophs whose cells do not have

cell walls.

Key Concept• What are the six kingdoms of life as

they are now identified?

–The six-kingdom system of –The six-kingdom system of

classification includes the kingdoms

Eubacteria, Archaebacteria, Protista,

Fungi, Plantae, and Animalia.

Key Concept • What is the three-domain system of

classification?

–The three domains are the domain

Eukarya, Which is composed of Eukarya, Which is composed of

protists, fungi, plants, and animals; the

domain Bacteria, which corresponds to

the kingdom Eubacteria; and the

domain Archaea, which corresponds to

the kingdom Archaebacteria.