Bacteria and archea

Bacteria

Earth's first organisms that thrive almost everywhere.

Prokaryotes

Organisms that reproduce through binary fission and have short-generation times.

Binary fission

A method of asexual reproduction in prokaryotes.

Transformation

The process where a cell takes up and incorporates foreign DNA from its environment.

Transduction

Movement of genes between bacteria by bacteriophages.

Conjugation

Transfer of genetic material between prokaryotic cells.

F factor

A plasmid that functions as a DNA donor during conjugation in prokaryotes.

Plasmids

Smaller rings of DNA in prokaryotes which can carry genes.

Polymerase chain reaction (PCR)

A method that allows for rapid sequencing of prokaryote genomes.

Horizontal gene transfer

The movement of genetic material between organisms other than by descent.

Cocci

Spherical shaped bacteria.

Bacilli

Rod shaped bacteria.

Peptidoglycan

A polymer that makes up the cell wall of bacteria.

Capsule

A polysaccharide or protein layer that covers many prokaryotes.

Fimbriae

Filamentous structures that enable bacteria to stick to surfaces or each other.

Pili

Longer than fimbriae, allowing prokaryotes to exchange DNA.

Taxis

The ability to move toward or away from a stimulus.

Chemotaxis

Movement toward or away from a chemical stimulus.

Flagella

Tail-like structures that aid in bacterial movement.

Exaptation

The process where existing structures take on new functions.

Gram-positive bacteria

Bacteria with simpler walls and a high amount of peptidoglycan.

Obligate aerobes

Organisms that require oxygen for cellular respiration.

Obligate anaerobes

Organisms poisoned by oxygen that use fermentation.

Facultative anaerobes

Organisms that can survive with or without oxygen.

Nitrogen fixing

The conversion of nitrogen gas into ammonia by certain bacteria.

Heterocysts

Specialized cells in some cyanobacteria that fix nitrogen.

Biofilms

Surface-coating colonies of different prokaryotic species.

Extremophiles

Organisms that live in extreme environments.

Halophiles

Organisms that thrive in highly saline environments.

Thermophiles

Organisms that thrive in very hot environments.

Methanogens

Strict anaerobes that produce methane as a waste product.

Mutualism

A type of symbiotic relationship where both organisms benefit.

Commensalism

A relationship where one organism benefits and the other is neither helped nor harmed.

Parasitism

A relationship where a parasite harms but does not kill its host.

Pathogens

Parasites that cause diseases in their host.

Exotoxins

Toxins secreted by bacteria that can cause disease even if the producer is absent.

Endotoxins

Toxins released only when bacteria die, breaking down cell walls.

Bioremediation

The use of organisms to remove pollutants.

Protist

An informal name for a diverse group of unicellular eukaryotes.

Plastids

Small organelles in plants that contain pigments or food.

Red algae

Multicellular algae with reddish color due to phycoerythrin.

Green algae

Land plant ancestors classified within the group charophytes.

Excavata

A supergroup of protists characterized by their cytoskeleton and feeding groove.

Diplomonads

Protists with reduced mitochondria and are often parasites.

Euglenozoa

A diverse clade of protists known for a spiral or crystalline rod inside their flagella.

Diatoms

Unicellular algae with a glass-like silica wall; important in carbon dioxide removal.

Alternation of generations

Life cycle that includes multicellular haploid and diploid forms.

Apicomplexans

Parasites of animals that require two or more host species to complete their life cycle.

Dinoflagellates

Photosynthetic protists with two flagella, known for causing harmful algal blooms.

Alpha bacteria

Part of the proteobacteria group, often involved in nitrogen fixation. They play a crucial role in converting atmospheric nitrogen into a form usable by plants, contributing significantly to soil fertility and ecosystem health. Well-known examples include Rhizobium species, which form symbiotic relationships with legumes.

Beta bacteria

Known for their role in the nitrogen cycle and include some pathogens. They help in the oxidation of ammonia to nitrite, which is a critical step in nitrification. Pathogenic members like Neisseria gonorrhoeae pose health risks to humans.

Gamma bacteria

Include many well-known pathogens and are often involved in biodegradation. This group includes Escherichia coli and Salmonella, both significant in human health. Additionally, they play roles in breaking down organic materials in various environments, contributing to nutrient cycling.

Delta bacteria

Primarily known for their role in sulfate reduction. These bacteria can reduce sulfate ions to sulfide, which is important in biogeochemical cycles, especially in aquatic environments. Desulfovibrio is a genus that exemplifies this group.

Epsilon bacteria

Associated with extreme environments and include organisms that can reduce metals. They are often found in acidic or extreme temperatures. Helicobacter pylori, for instance, is an epsilon bacterium that can survive the harsh conditions of the human stomach.