Prokaryotes and the Origins of Metabolic Diversity

Flashcards covering key concepts about prokaryotes, their diversity, metabolism, and ecological impacts.

Prokaryotes

Single-celled organisms that evolved approximately 3.5 billion years ago and are structurally and metabolically diverse.

Domain Bacteria

Majority of prokaryotes characterized by cell walls containing peptidoglycan.

Peptidoglycan

Polymers of modified sugars cross-linked by short polypeptides found in bacterial cell walls.

Domain Archaea

A group of prokaryotes whose cell walls lack peptidoglycan and possess unique polysaccharides.

Methanogens

Archaea that use hydrogen to reduce carbon dioxide to methane and are strictly anaerobic.

Extreme halophiles

Organisms that inhabit high salinity environments and possess unique adaptations like bacteriorhodopsin.

Cyanobacteria

Photosynthetic bacteria that altered the Earth’s atmosphere by producing oxygen.

Nitrogen fixation

The conversion of atmospheric nitrogen (N2) into ammonium (NH4+) by certain bacteria.

Gram-positive bacteria

Bacteria that retain violet dye due to simpler cell walls with a large amount of peptidoglycan.

Gram-negative bacteria

Bacteria that have more complex cell walls with an outer membrane and a thinner layer of peptidoglycan.

Binary fission

Asexual reproduction in prokaryotes where one cell divides into two.

Plasmid

A small ring of DNA in prokaryotes that can replicate independently and often carries genes for antibiotic resistance.

Photoautotrophs

Organisms that use light energy to synthesize organic compounds from carbon dioxide.

Chemotrophs

Organisms that obtain energy by oxidizing chemicals taken from the environment.

Saprobes

Decomposers that absorb nutrients from dead organic matter.

Obligate aerobes

Prokaryotes that require oxygen for cellular respiration.

Facultative anaerobes

Prokaryotes that can use oxygen when present but can grow without it through fermentation.

Obligate anaerobes

Prokaryotes that are poisoned by oxygen and utilize other electron acceptors.