Archaea Flashcards
There are _____ known archaeal human pathogens
no
All known _________-producing organisms are archaea
methane
What did Carl Woese do?
Founded the third domain, archaea
What were the first archaea?
methanogens
What is the most common size range of archaea?
0.5-5um
What does the archaeal cell envelope consist of?
Plasma membrane, most have a cell wall, most do not have outer membrane
Describe the plasma membrane of archaea and why it is different from bacteria and eukarya
- G1P instead of G3P
- Ether linkages instead of ester linkages
- Repeating isoprene units of phytanyl instead of fatty acid tails
- This structure is more stable at high temperatures
- Some archaea have monolayers
Describe the structure of archaeal cell wall
- composed of pseudomurein instead of peptidoglycan
- N-acetylglucosamine (NAG) and N-acetyltalosaminuronic acid (NAT) instead of NAG and NAM
- L-amino acids instead of D-amino acids
What is an s-layer?
A characteristic of some archaea that most likely protects against predation/viruses
What is cannulae and what does it do?
Hollow glycoprotein tubes that link cells together after they divide in a network to exchange materials amongst each other
What are the differences between flagellum and archaellum?
- Archaellum grows from the base like hair instead of the tip
- Uses ATP and not proton motive force
- They are not evolutionarily related
What are the four major phyla of archaea?
Euryarchaeota
Crenarchaeota
Thaumarchaeota
Nanoarchaeota
Identifiers of Crenarchaeota
- thermophiles and hyperthermophiles
Identify and define some common thermophiles
acidophiles - acid loving (thrive in low pH)
barophiles - thrive in high pressure
What adaptations do crenarchaeota have to survive in extreme environments?
- Lipid monolayers
- More a-helix (more stable) than b-sheets
- More arginine and tyrosine than cysteine and serine
- More reverse DNA gyrase enzymes (type of topoisomerase) so more DNA supercoiling
Name two common types Euryarchaeota
halophiles (salt-loving) and methanogens (methane producing)
How do halophiles deal with osmotic shock and loss of water?
High intracellular [K+] offsets very high extracellular [Na+] so they trick their environment into becoming isotonic
What is bacteriorhodopsin?
- A protein that harnesses light energy and produces PMF
- Reddish hue is given off due to retinal (vitamin A)
All methanogens are __________
anaerobes
Where are methanogens found?
Human and animal digestive tracts, swamp sediment, landfills
What does superphylum TACK stand for?
Thaumarchaeota, aigarchaeota, crenarchaeota, korarchaeota
Key features of Thaumarchaeota
- Now called Nitrosphaerota
- Ammonium oxidizing
Key features of superphylum DPANN
- Very, very small archaea
- Small genomes
- Restricted metabolisms
- Contains nanoarchaeum
Describe Nanoarchaeota
- Probably the smallest living organism
- 16S rRNA gene sequences
Describe the relationship between Nanoarchaeum and Ignicoccus
- Nanoarchaeum is so small that it doesn’t have space for metabolic genes
- Outsources ATP production, amino acids, etc. from Ignicoccus
- Relationship may be parasitic or mutualistic
- Ignicoccus has a weird shape with little cytoplasm and ATP is produced on outer membrane
Key features of Lokiarchaeota/Thorarchaeota
- Possible closest living ancestor to Eukaryotes
- Thermophilic
