Chapter 27: Bacteria and Archaea

Prokaryotes

Domains Bacteria and Archaea; Ubiquitous; single-celled; microscopic

Some functions of prokaryotes

decomposers; add usable nitrogen to the environment; in our bodies

Domain Archaea: Kingdom Archaebacteria

cell walls (Polysaccharides & proteins), cell membranes; ribosomal RNA differ significantly from bacteria

Extremophiles

live where nothing else can; Extremozymes

Types of Archaebacteria

Extreme Thermophiles/Halophiles, Methanogens, Acidophiles

Greek Root ~Philos

Lover

Greek root ~Thermo

Heat

Greek root ~Halo

Salt

Types of Extreme thermophiles

Thermus aquaticus, Thermococcus litoralis, Pyrococcus

Types of Extreme halophiles

Halobacterium salinarum, Haloferax volcanii, Natronobacterium gregoryi

Types of Methanogens

Methanobacterium, Methanocaldococcus, Methanosarcina

Kingdom Eubacteria

all over our bodies; prokaryotic microorganisms; single-celled; lacks a nucleus; contains DNA in a single circular chromosome

Symbiosis

ecological relationship where two species live in close contact; larger host and smaller symbiont; prokaryotes often form symbiotic relationships with larger organisms

Mutualism

both symbiotic organisms benefit

Commensalism

one organism benefits while neither harming nor helping the other in any significant

Parasitism

an organism called a parasite harms but does not kill its host; pathogens

Cocci

spherical

Bacilli

rod-shaped

Spiral

spiral shape

Gram stain

can be Gram-positive or Gram-negative based on cell wall composition

Gram-negative bacteria

less peptidoglycan and an outer membrane that can be toxic; more likely to be antibiotic resistant; pink/red stain

Ex: Spirochetes, Chlamydia, Cyanobacteria

Gram-positive bacteria

thick cell wall made of peptidoglycan; purple stain

Ex: Bacillus anthacis, Clostridium botulinum

Key features of all bacteria

Cytoplasm, Ribosomes, Plasma Membrane, Nucleoid containing DNA

Bacterial cell wall

mantains cell shape, physical protection, prevents cell from bursting, contains peptidoglycan

Fimbriae

allows bacteria to stick to their substrate or other individuals in a colony

Pili

allows prokaryotes to exchange DNA and Conjugation

Capsule

made of Polysaccharides and Proteins; firmly attached to cell surface; prevents Phagocytosis; Virulence factor

Virulence Factor

any characteristic of bacteria that contributes to its ability to establish itself in the host and cause damage

Flagella

long, thread-like structures for movement; most motile bacteria propel themselves with this

Chemotaxis

moving to or away from chemical nutrients

Phototaxis

moving to or away from light

Endospores

dehydrated bacteria; withstand harsh conditions; resistant to high temps; can last for centuries

Genetic material in Bacteria

circular chromosome in nucleoid region

Plasmid

smaller, circular piece of DNA in addition to circular chromosome; R plasmids = antibiotic resistance. F plasmid = genes fertility

Bacterial Reproduction

Binary fission: divide every 1-3 hrs., Logarithmic growth, mutations can accumulate rapidly (rapid evolution of prokaryotes)

Transformation

new sequence introduced

Transduction

new sequence from Bacteriophage (viruses that infect bacteria)

Conjugation

new sequence from Plasmid exchange

Aerobic prokaryote

respiratory membrane

Photosynthetic prokaryote

Thylakoid membrane

Phototrophs

obtain energy from light

Chemotrophs

obtain energy from chemicals

Autotrophs

require CO2 as a carbon source

Heterotrophs

require an organic nutrient to make organic compounds (consumers)

Obligate aerobes

require O2 for cellular respiration

Obligate anaerobes

poisoned O2 and use fermentation or anaerobic respiration

Facultative anaerobes

can survive with with or without O2

Biofilms

metabolic cooperation that occurs in surface-coating colonies

Exotoxins

cause disease even if prokaryotes that produce them are not present

Ex: Vibrio cholerae, Clostridium botulinum

Endotoxins

released only when bacteria die and their cell walls break down, Lipopolysaccharides from outer membrane of Gram-negative Bacteria

Ex: Salmonella typhi

Proteobacteria

Gram-negative; phototrophs, chemoautotrophs, and heterotrophs; aerobic or anaerobic

Ex: Neisseria gonorrhoeae, Vibrio cholerae, Helicobacter pilori

Spirochetes

helical heterotrophs, rotating internal flagella like filaments; Gram-negative, some free living, some parasites

Parasites: Treponema pallidum (syphilis), Borrelia burgdorferi (Lyme Disease- caused by Deer ticks)

Cyanobacteria

photoautotrophs that generate O2, blue-green algae; Gram-negative

Chlamydias

parasites living in animal cells; Chlamydia trachomatis

Beneficial Prokaryotes

Bioremediation - decontamination of soil and water from industrial and human pollution

Recovery of metals from ores

Synthesis of vitamins

Production of antibiotics and hormones

Bioplastics

PCR Technology (Archaea)

CRISPR Gene editing technology