L13 Bacteria & Archaea pt 2 Flashcards
how are prokaryotes classified
by dividing them into classes, and further into species
what are 6 groups of bacteria
- proteobacteria
- green bacteria
- cyanobacteria
- gram-positive bacteria
- spirochetes
- chlamydia
what is the key distinguishing feature of the different groups of bacteria
composition of the cell wall
what is the most diverse group of bacteria
proteobacteria
describe gram-negative bacteria
-purple sulfur bacteria (their colour is caused by a specific type of chlorophyll)
-photoautotrophic or photoheterotrophic
describe free-living gram-negative proteobacteria
- chemoheterotrophs
- includes intestinal bacteria
- some of these cause diseases (bubonic plague, gonorrhea, gastroenteritis, dysentery)
What is a type of green bacteria? describe this
- gram-negative photosynthetic bacteria
- photoautotrophic are found in hot springs
- photoheterotrophic are found in marine and high salt environments
- distinctive chlorophyll compared to plants
- don’t release oxygen during photosynthesis
describe cyanobacteria
- include blue-green algae and gram-negative aerobic photosynthetic prokaryotes
- responsible for oxygen-based life on earth
- some make colonies, have specialized cell types (heterocysts for nitrogen fixation)
what is the most morphologically diverse group of bacteria
cyanobacteria
describe gram-positive bacteria
- give positive result on gram stain test
- thicker peptidoglycan on outside
- mainly chemoheterotrophs
- has many pathogenic species
- some species are beneficial
bacillus anthracis
rod-shaped bacteria causing anthrax
staphylococcus
sphere shaped bacteria causing:
- food poisoning
- toxic shock syndrome
- pneumonia
- bacterial meningitis
streptococcus
- sphere-shaped bacteria causing:
- strep throat
- pneumonia
- necrotizing fasciitis
lactobacillus
Rod shaped bacteria using lactic acid fermentation to make pickles, kimchi, sauerkraut, yogurt
describe spirochetes, what type of bacteria are they?
- +/- species
- propelled by rotation of flagella (movement in thick mud or sewage)
- found in human mouth, termite intestines that digest cellulose
- some pathogenic species (e.g. syphilis)
- type of gram-negative bacteria
describe chlamydias, what type of bacteria are they?
- obligate intracellular pathogens of humans and animals
- type of gram-negative bacteria
- cause STIs and respiratory infections
- cell walls lack peptidoglycan
- significantly reduced genome size compared to other bacteria
why are deinococcus radiodurans unique
- tolerant to radiation
- can break down radioactive waste
why are thermus aquaticus unique
- tolerant to high temperatures
- DNA polymerase is very heat stable
- PCR techniques to make copies of DNA sequences for genetic engineering
why are archaea unique
- features similar to bacteria (prokaryote, chromosomes, ribosomes) and eukaryotes (histones, enzymes)
- unique features (membranes and protein synthesis)
what are the main phyla of archaea
euryarchaeota, crenarchaeota, korarchaeota, thaumarchaeota
what are similarities between archaea and bacteria
- do not contain nucleus or membrane-bound organelles
- circular DNA
- same ribosome size (70S)
- can grow at temperatures of 80C +
- operons in DNA, introns in most genes
- fixate nitrogen, complete chemoautotrophy
what are differences between bacteria and archaea
- membranes of bacteria are ester-linked
- bacteria completes photosynthesis with chlorophyll
- bacteria are sensitive to antibiotics
- histone proteins are in archaea cells
- archaea can complete methanogenesis
what are 3 types of euryarchaeota
methanogens, halophiles, extreme thermophiles
describe methanogens
- methane producing
- living in low oxygen environments
- anaerobic in organs of animals (stomachs, rumen)
- swamps, lakes, marshes, sewage works
describe halophiles
- live in highly salted environments
- are aerobic chemotrophs
- get energy from sugars, alcohols, amino acids, or light as secondary energy source
describe thermophiles
- live in extremely hot environments like hydrothermal vents and hot springs
- tolerate temps between 70C and 95C
what are 3 types of crenarchaeota
extreme thermophiles, psychrophiles, mesophiles
describe extreme thermophiles (cren.)
- higher optimal temp range than euryarchaeota
- sulfur dependent
describe psychrophiles
- love cold
- thrive at temp between -10C to -20C
- found in arctic and antarctic oceans
describe mesophiles
marine plankton in cool waters
describe korarchaeota
- Recognized only by sequences in DNA samples
- Found in hydrothermal environments but have never been isolated and cultivated in lab
- Nothing known about their physiology
describe thaumarchaeota
- initially known as mesophilic crenarchaeotes
- likely most abundant cells in oceans
- chemoautotrophs using ammonia
what is the TACK acronym
Thaumarchaeota
Aigarcheota
Crenarchaeota
Korarchaeota
what is the human microbiome
- prokaryotes that live on and within human body
- estimated that bacterial and archaeal cells outnumber human cells by 10 to 1 ratio but new research suggests ~1 to 1 ratio
- bacterial and archaeal genes outnumber human genes by 100 to 1
when are intestinal bacteria beneficial
- break down food
- secrete vitamins, biomolecules into colon for nutrient absorption
- makes molecules that signal other systems such as immune and nervous system
compare african microbiome to western microbiome
- plant-based vs. sugar and fat based
- dominated by bacteroidetes vs firmicutes
- african microbiome can digest plant fiber
what are prokaryotes important to study
- medicine
- ecosystem processes
- talents
- biotechnology, bioprocessing, biomimicry
- research into human microbiome and human interactions
describe the evolutionary history of prokaryotes
- TACK
- network as opposed to tree
- evolution of bacteria and archaea seen as important part of evolution of eukarya
