Bacteria, Protists, and Fungi

Prokaryote Key Features

Organisms that lack a nucleus and membrane-bound organelles with circular DNA located in a nucleoid region.

Eukaryote Key Features

Organisms that contain a membrane-bound nucleus and specialized organelles such as mitochondria and the Golgi apparatus.

Early Life Appearance

Life was exclusively unicellular and anaerobic because it lived in environments without oxygen like hydrothermal vents.

Peptidoglycan

A structural polymer found in the cell walls of Bacteria that is notably absent in Archaea and Eukarya.

Archaea Traits

Prokaryotes that often live in extreme environments and share more genetic similarities with Eukaryotes than Bacteria do.

Protist Definition

Any eukaryotic organism that is not classified as a plant, animal, or fungus.

Key Characteristics

A highly diverse group where most members are unicellular though some like kelp are multicellular.

Endosymbiosis Origin

The theory that Protists resulted from primary and secondary endosymbiosis events involving ancient bacteria.

How a Fungus Lives

Most fungi are saprobes that act as decomposers by using absorptive heterotrophy to digest food externally.

Hyphae and Mycelium

The body of a fungus consists of thread-like filaments called hyphae which bundle together to form a mass called a mycelium.

Chitin

The structural carbohydrate found in fungal cell walls and the exoskeletons of insects.

Ecological Roles

Fungi function in ecosystems as essential decomposers, specialized parasites, or mutualistic partners.

Chytridiomycota

The only fungal group with flagellated spores called zoospores which are often found in aquatic environments.

Zygomycota

Fast-growing molds that produce a hardy structure called a zygosporangium during their sexual reproduction phase.

Glomeromycota

A group of fungi that form arbuscular mycorrhizae by penetrating the root cells of nearly all vascular plants.

Ascomycota

Known as sac fungi, this group includes yeasts and truffles which produce spores in sac-like structures called asci.

Basidiomycota

Known as club fungi, this group includes classic mushrooms and puffballs which produce spores on club-shaped structures called basidia.

Mycorrhizae

A mutualistic relationship between fungi and plant roots that is essential for the survival of most vascular plants.

Ectomycorrhizae

Fungi that form a sheath around the outside of root cells rather than penetrating the cell walls.

Endomycorrhizae

Fungi that belong to the Glomeromycete group and physically penetrate the cell walls of plant roots.

Lichen Definition

A symbiotic association between a fungus and a photosynthetic partner such as green algae or cyanobacteria.

Lichen Roles

These organisms act as pioneer species that break down rock into soil and serve as indicators of air quality.