BIO 152 - QUIZ 2, Chapter 18 Bacteria and Archaea

Kingdoms

• taxonomic divisions by Linnaeus

• Broadest, most inclusive taxonomic rank

• Until recently did not reflect evolutionary reality

Kingdom Protista

a ‘mixed bag’ of eukaryotes

Domains

• were proposed to better reflect evolutionary relationships among organisms

  • based on the type of cell in the organism, differences in ribosomes, cell walls and cell membranes

Bacteria

• prokaryotic cells

• Ester - linked, unbranched lipids

• peptidoglycan cell wall

• 70s ribosome

Archaea

• prokaryotic cells

• ether-linked, branching lipids

• cell wall not peptidoglycan

• 70s

Eukarya

• Eukaryotic cells

• ester-linked unbranched lipids

• cell walls absent or peptidoglycan

• 80s ribosome

• Evolved from an archean ancestor

Characteristics of Prokaryotes

• Small, single celled

• No nucleus; DNA is found in a single, circular chromosome

• No membrane bound organelles, ribosomes present

• Cell is surrounded by cell wall, peptidoglycan in bacteria, other substances in archaeans

• Cells divide by binary fission

• Genetic diversity is acquired by mutation, conjugation or transformation

Conjugation

sharing of DNA

Transformation

picking up DNA from the environment

Gram Positive Prokaryotes

• have a think cell wall dyed with violet stain

Gram Negative Prokaryotes

• prokaryotes have a think cell wall surrounded by an external membrane

• these have to be ‘counterstained’ with a pink dye

How prokaryotes evolved in a very different environment…..

1) the planet was very hot, there was no (or very little) oxygen, etc.

2) many prokaryotes that evolved under these conditions are still found in similar environments

Extreamophiles

any organism that prefers or thrives in environments in which some condition, quantity, or resource is at such a level that is would kill most other organisms

Thermophile

thrives in extremely high temperatures (approx. 95C)

Acidophiles

thrives in extremely acidic environments

Halophile

thrives in extremely salty environments

Hadobacteria

• ‘bacteria from hell’

  • thrive 90-95C

Deinococcus

• can withstand nuclear radiation and consume nuclear waste; can also withstand extremes of very low and very high temps

Thermus aquaticus

• lives in hot springs (and your water heater); have a thermally stable DNA polymerase used in biotech

Hyperthermophiles

thrive at or even above boiling temps

Aquifex

• one of the simplest organisms, both structurally and metabolically

• can live using only hydrogen oxygen, carbon dioxide or mineral salts

Firmicutes

• Small

• unusual in that they tend to have fewer G-C pairs in their DNA than T-A pairs

• many species that cause disease

• Also beneficial members of human gut flora

Actinobacteria

• have unusual growth from that resembles branching filaments

• Tend to have more G-C base pairs in their DNA than T-A pairs

• Causes tuberculosis

• Common for antibiotics are produced from this type of bacteria

Cyanobacteria

• first organism to engage in oxygenic photosynthesis

• use Chlorophyll A as photosynthetic pigment

• photosynthesis is carried out in special folds of the plasma membrane

• ARE chloroplasts

• single celled but some live in colonies

Photosynthetic Lamellae

photosynthesis is carried out by special folds in the plasma membrane

In cyanobacteria colonies …

• vegetative cells perform photosynthesis

• heterocysts perform nitrogen fixation

• Spores / resting cysts are cells that allow the individual to become dormant during difficult environmental conditions

Spirochaetes

• “Spiral bristles”

• Gram-Negative

• spiral shaped cell wall and outer membrane

• Corkscrew movement

• responsible for diseases like syphilis and lyme disease

Chlamydias

• very small, parasitic bacteria that can cause highly contagious infections

• have special enzyme (translocase) that can move ATP from its host cell into its own

Proteobacteria

• largest and most diverse group of bacteria

• many harmless, innocuous and ecologically beneficial species

• several can cause severe illness and death in organisms (E. Coli, bubonic plage, Cholera)

Archeans

• “ancient ones”

• sequencing of rRNA revealed that they were distinct from bacteria, more derived

• many are common soil microbes

  • some live in aquatic environments, both freshwater and marine

Pathogenic Bacteria

• bacteria that infects humans and other organisms in order to feed and have a safe environments

• rapid reproduction allows them to overwhelm their host’s immune defenses

• endotoxins are released when bacteria burst; often non-lethal that cause aches, fevers and gastrointestinal unrest

Endotoxins

• secreted by living bacteria

• can be extremely lethal (anthrax, plague, tetanus)

Aerobic Prokaryotes

have to live in presence of oxygen because they produce ATP via aerobic respiration

Anaerobic Prokaryotes

• obligate anaerobes

• facultative anaerobes

• Aerotolerant / microaerophilic

Obligate anaerobes

cannot survive in the presence of oxygen, and only engage in anaerobic respiration

Facultative anaerobes

can survive in either aerobic or anaerobic conditions and can switch their respiration accordingly

Aerotolerant / Microaerophilic organisms

conducts anaerobic respiration but can tolerate small amounts of oxygen

All organisms need….

energy and carbon

Energy

is needed to do work

Carbon

is needed to build macromolecules

Photoautotrophs

• some bacteria, some eukaryotes

• Energy = light

• Carbon Source = Carbon Dioxide

• perform photosynthesis

Photoheterotrophs

• some bacteria

• Energy = light

• Carbon Source = organic compounds

Chemoautotrophs

• some bacteria, many prokaryotic archaea

• Energy = inorganic substances

• Carbon Source = carbon dioxide

Chemoheterotrophs

• some bacteria, some prokaryotic archaea, most eukaryotes

• Energy = usually organic compounds, sometimes inorganic substances

• Carbon Source = organic compounds

Nitrifying microbes

• able to convert atmospheric N2 into NH3, making lots of nitrogen available to producers and in turn consumers

Nitrogenase

• enzyme

• extremely sensitive to oxygen

Denitrifying Microbes

• convert nitrate (NO2) back into atmospheric N2

• prevents nitrogen from becoming sequestered in aquatic habitats

Last common ancestor of all living organisms

about 3.0 billion years ago

Endosymbiosis with bacteria

• resulted in mitochondria of eukaryotes

• chloroplasts of photosynthesizers

Peptidoglycan

• a cross-linked polymer of amino sugars that produces a firm, protective, mesh-like structure around the cell

• unique to bacteria

Coccus

spherical bacterium

Bacillus

a rod-shaped bacterium

Spirillum

spiral bacterium

Binary Fission

asexual process

Environmental genomics

when biologists are unable to work with a single prokaryotic species, instead examine genomes colleged from an environmental sample

Microbiomes

communities of bacteria and prokaryotic archaea that live in and on our bodies