Bacteria & Archaea: The Prokaryotic Domains

What are the three domains?

Bacteria, Archaea, and Eukarya

Most microbes are…

Bacteria or archaea and are unnamed and undescribed.

What are evolutionary relationships revealed by?

rRNA sequences (ribosomal sequences)

The most ancient prokaryotes are…

thermophiles

What are the most numerous organisms on Earth?

Extremophile prokaryotes

What are the different kinds of extremophiles?

Thermophiles (live in hot environments), halophiles (live in salty environments), acidophiles (live in acidic environments), and methanogens (produce methane by reducing carbon dioxide— exist within the guts of herbivores like cattle and termites).

What varies a lot in prokaryotes?

Cell size

What are the different body types of prokaryotes?

Cocci (round), bacilli (rod), and spirilli (spiral)

T/F: Very few prokaryotes can be truly multicellular.

TRUE

What is an example of a prokaryote that is multicellular?

Myxobacteria

What do prokaryotes contain?

They lack nuclei, membrane-enclosed organelles, and cytoskeletons but have a single chromosome (DNA) that is circular and ribosomes to make protein. They often contain plasmids.

Plasmids

Small bits of DNA

How do prokaryotes move?

Uses rotating flagella

What are the cell walls made out of?

Peptidoglycan or polysaccharides

Bacteria vs. Archaea

Bacteria are prokaryotic, have cell walls made of peptidoglycan, a plasma membrane similar to eukaryotes, distinct ribosomes and RNA polymerase, and some can be pathogenic.

Archaea are prokaryotic and unicellular, have a unique plasma membrane, have a cell wall made of polysaccharides, have ribosomes and RNA polymerase similar to eukaryotes, and there are no known pathogens.

What structure is unique to archaea?

Archaeal phospholipid membrane structures

How to prokaryotes reproduce?

Asexually by binary/cell fission (can also exchange genetic information via pieces of DNA/plasmids)

What are the different types of metabolism for prokaryotes?

Photo (uses light energy), chemo (uses chemical energy), autotroph (uses CO2 for carbon), and heterotroph (uses other resources for carbon)

T/F: Only some bacteria are photoheterotrophs and only some bacteria and some archaea are chemoautotrophs.

TRUE

What are the three ways that archaea and bacteria produce energy (ATP)?

Phototrophs: use light energy to produce ATP through cellular respiration.

Organotrophs: oxidizes organic molecules to make ATP through cellular respiration/fermentation.

Lithotrophs: oxidizes inorganic molecules where ATP is made by cellular respiration with the inorganic compound serving as the electron donor.

What do bacteria have a key role in? How?

Global nitrogen and sulfur cycles (nitrogen fixation). Bacteria can make nitrogen from N2 into a form usable by plants.

Black Death

An example of harmful prokaryotes living on other organisms.

T/F: Minority of bacteria are pathogens and they are rarely fatal.

TRUE

What are some examples of highly toxic bacteria?

Tetanus, botulism, cholera, plague, anthrax, and some STD’s.

Koch’s Postulates

A way to confirm a causative link between a specific infectious disease and an infectious microbe.

What are Koch’s Postulates?

1) Microbe present in diseased individuals and not in healthy ones

2) Organism must be isolated and grown in a pure culture away from the host organism

3) Injection of organisms from culture into a healthy animal results in disease

4) Organism isolated from diseased animal (again, grown in pure culture) and is the same organism

Prokaryotic Remediation

Use of bacteria and archaea to degrade pollutants (beneficial because it aids in the production of antibiotics, vitamins, insulin, and pollution cleanup)

Phytoremediation

Uses living plants to remove, degrade, or stabilize pollutants in soil, water, and air

Mycoplasmas

Smallest living things that lack cell walls (may cause some human diseases)