Archaea

Question 1

There are _____ known archaeal human pathogens

Answer 1

no

Question 2

All known _________-producing organisms are archaea

Answer 2

methane

Question 3

What did Carl Woese do?

Answer 3

Founded the third domain, archaea

Question 4

What were the first archaea?

Answer 4

methanogens

Question 5

What is the most common size range of archaea?

Answer 5

0.5-5um

Question 6

What does the archaeal cell envelope consist of?

Answer 6

Plasma membrane, most have a cell wall, most do not have outer membrane

Question 7

Describe the plasma membrane of archaea and why it is different from bacteria and eukarya

Answer 7

• 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

Question 8

Describe the structure of archaeal cell wall

Answer 8

• 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

Question 9

What is an s-layer?

Answer 9

A characteristic of some archaea that most likely protects against predation/viruses

Question 10

What is cannulae and what does it do?

Answer 10

Hollow glycoprotein tubes that link cells together after they divide in a network to exchange materials amongst each other

Question 11

What are the differences between flagellum and archaellum?

Answer 11

• Archaellum grows from the base like hair instead of the tip
• Uses ATP and not proton motive force
• They are not evolutionarily related

Question 12

What are the four major phyla of archaea?

Answer 12

Euryarchaeota
Crenarchaeota
Thaumarchaeota
Nanoarchaeota

Question 13

Identifiers of Crenarchaeota

Answer 13

• thermophiles and hyperthermophiles

Question 14

Identify and define some common thermophiles

Answer 14

acidophiles - acid loving (thrive in low pH)
barophiles - thrive in high pressure

Question 15

What adaptations do crenarchaeota have to survive in extreme environments?

Answer 15

• 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

Question 16

Name two common types Euryarchaeota

Answer 16

halophiles (salt-loving) and methanogens (methane producing)

Question 17

How do halophiles deal with osmotic shock and loss of water?

Answer 17

High intracellular [K+] offsets very high extracellular [Na+] so they trick their environment into becoming isotonic

Question 18

What is bacteriorhodopsin?

Answer 18

• A protein that harnesses light energy and produces PMF
• Reddish hue is given off due to retinal (vitamin A)

Question 19

All methanogens are __________

Answer 19

anaerobes

Question 20

Where are methanogens found?

Answer 20

Human and animal digestive tracts, swamp sediment, landfills

Question 21

What does superphylum TACK stand for?

Answer 21

Thaumarchaeota, aigarchaeota, crenarchaeota, korarchaeota

Question 22

Key features of Thaumarchaeota

Answer 22

• Now called Nitrosphaerota
• Ammonium oxidizing

Question 23

Key features of superphylum DPANN

Answer 23

• Very, very small archaea
• Small genomes
• Restricted metabolisms
• Contains nanoarchaeum

Question 24

Describe Nanoarchaeota

Answer 24

• Probably the smallest living organism
• 16S rRNA gene sequences

Question 25

Describe the relationship between Nanoarchaeum and Ignicoccus

Answer 25

• 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

Question 26

Key features of Lokiarchaeota/Thorarchaeota

Answer 26

• Possible closest living ancestor to Eukaryotes
• Thermophilic