chapter 27: Bacteria & Archaea

Peptidoglycan

Network of sugar polymers crosslinked by polypeptides. Usually a part of the Bacterial Cell walls.

Gram positive bacteria

Simpler walls with large amount of peptidoglycan. Usually Violet

Gram negative bacteria

Less peptidoglycan & an outer membrane containing lipopolysaccharides. Usually red

Capsule

A sticky outer layer of polysaccharide or protein. A protective outer layer that helps bacteria adhere to surfaces, resist immune systems, and prevent dehydration.

Fimbriae

Hairline appendages; allowing them to stick to their substrate or other individuals in a colony.

Pili

Longer than fimbriae and allow projaryotes to exchange DNA.

Endospores

Durable, dormant structure formed by certain bacteria as a survival mechanism to withstand harsh environmental conditions like heat, radiation, and desiccation

Taxis

The ability to move toward or away from a stimulus.

Ie. Chemotaxis- movement toward or away from chemical stimulus.

Flagella

Structure used for movement; may be scattered about surface or concentrated at one or both ends of the cell.

Horizontal gene transfer

Movement of genes among individuals from different species.

Transformation

Prokaryotic cell can take up and incorporate foreign DNA from the environment.

Transduction

Movement of genes between bacteria by phages (from bacteriophages, viruses that infect bacteria)

R plasmids

Carry genes for antibiotic resistance.

Obligated aerobes

Require o2 for cellular respiration.

Obligated anaerobes

Are poisoned by o2 and live by fermentation or use substances other than o2 for anaerobic respiration

Facultative anaerobes

Can use o2 if it is present or carry out fermentation or anaerobic respiration if ot is not.

Heterocysts

Nitrogen fixing cells

Nitrogen fixation

N2> NH3

Chlamydia

Bacteria that’s a parasite living within animal cells.

Chlamydia trachomalis → blindness and nongonococcal urethritis by sexual transmission.

Spirochetes

Helical gram-negative heterotrophs

Some are parasites:

Treponema Pallidum →syphilis

Borrelia burgdorferi → Lyme disease

Cyanobacteria

Gram-negative photoautotrophs that generation o2

Plant chloroplasts likely evolved from cyanobacteria by the process of endosymbiosis.

Abundant components of freshwater & marine phytoplankton.

Mycoplasms

The smallest known cells, lack cell walls

Extremophiles

Live in extreme environments

Extreme halophiles

Live in highly saline environments

Extreme Thermophiles

Thrive in very hot environments

Methanogens

Live in swamps & marshes and produce methane as a waste product.

F factor Plasmid

Function as DNA donors during conjugation

Symbiosis

Ecological relationship in which 2 species live in close contact; A larger Host and a smaller symbiont.

Prokaryotes often form symbiotic relationships with larger organisms.

Mutualism

Both symbiotic organisms benefit

Commensalism

One organisms benefits while neither harming nor helping the other in any significant way.

Parasitsm

An organism called a parasite harms but does not kill the host.

Pathogens

Parasites that cause disease.