Microorganism Reading Week 4

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What did Carl Woese reveal in 1977?

The differentiation between animals and bacteria

The identification of a new domain of life - archaea (correct)

The existence of viruses

The discovery of plants

Which statement about methanogens is true?

They inhabit the digestive tracts of animals

They are found only in aerobic soil

Both A and B (correct)

None of the above

What is a characteristic of archaea known for?

They include hyperthermophiles and hyperacidophiles (correct)

Archaea are not found in extreme environments

They cause various diseases in humans

They are photosynthetic organisms

How do many archaea interact with bacteria?

They form multispecies biofilms together Signup and view all the answers

What is a key trait that archaea share with eukaryotes?

RNA machinery Signup and view all the answers

Which type of lipids are found exclusively in archaea?

Ether-linked membrane lipids Signup and view all the answers

What type of links connect the glycerol units to side chains in archaeal membrane lipids?

Ether links (R-O-R) Signup and view all the answers

What is the significance of ether lipids in archaea?

They increase lipid stability in extreme environments Signup and view all the answers

Why do some thermophilic bacteria have ether lipids similar to archaea?

Due to horizontal gene transfer from archaea Signup and view all the answers

What is the key energetic role of methanogens in ecosystems?

Serving as a mechanism for removing excess H2 Signup and view all the answers

Which branch of Euryarchaeota are extreme halophiles that grow in concentrated brine?

Haloarchaea Signup and view all the answers

What is the most distinguishing feature of archaeal membranes?

Composed of L-glycerol diether or tetraether lipids Signup and view all the answers

Which metabolic pathway is NOT found in archaea?

Krebs cycle Signup and view all the answers

What is the most significant characteristic of the Asgard superphylum?

Genomic evidence of relatedness to eukaryotes Signup and view all the answers

What is the purpose of isoprenoid branched chains in archaeal lipids?

To hook each other in place and increase membrane stability Signup and view all the answers

How do archaeal flagella, or archaella, differ from bacterial flagella?

They evolved independently from bacterial flagella Signup and view all the answers

What distinguishes the genome structure of archaea from that of bacteria and eukaryotes?

Presence of nontranslated introns in certain tRNA gene sequences Signup and view all the answers

What is the function of reverse gyrase enzymes in hyperthermophilic archaea?

Overwind DNA and prevent helix melting at high temperatures Signup and view all the answers

What is a defining feature of the TACK superphylum of archaea?

Presence of major clades discovered at deep-sea marine hydrothermal vents and hot springs Signup and view all the answers

What type of organisms grow only at high pressure?

Barophiles Signup and view all the answers

Which group of hyperthermophiles includes species that form dense biofilms?

Desulfurococcales Signup and view all the answers

What is the primary genetic material found in all known archaeal viruses?

Double-stranded DNA Signup and view all the answers

Which structure is formed as a result of the upwelling of seawater superheated by an undersea magma chamber?

Black Smoker Signup and view all the answers

What feature do Pyrodictium species possess in their cell structure?

Interconnected disk-shaped cells Signup and view all the answers

Where do psychrophilic marine methanogens primarily grow?

Deep within the seafloor Signup and view all the answers

What is the key role of methanogens in gaining energy?

Utilizing H2 to reduce CO2 and other small molecules Signup and view all the answers

What is a common habitat of methanogens?

Wetland soil Signup and view all the answers

Which two species are the main methanogens found in the human colon?

Methanosphaera stadtmanae and Methanobrevibacter smithii Signup and view all the answers

What are methane gas hydrates?

Crystalline structures trapping methane under pressure Signup and view all the answers

How do haloarchaea adapt to high external NaCl?

By maintaining a high intracellular concentration of potassium chloride Signup and view all the answers

What physiological adaptation is associated with the high GC content of DNA in haloarchaea?

Protection of DNA from denaturation in high salt Signup and view all the answers

What is the purpose of the acidic proteins found in haloarchaea?

To maintain a layer of water with hydrated potassium ions Signup and view all the answers

What is the composition of gas vesicles in haloarchaea?

Protein-based Signup and view all the answers

What is a key feature that distinguishes the cell envelopes of haloarchaea?

Rigid cell walls made of glycoprotein Signup and view all the answers

What is the primary energy source utilized by Haloarchaea for growth?

Photosynthesis Signup and view all the answers

Which unique feature allows Haloarchaea to remain near the top of the water column?

Gas vesicles Signup and view all the answers

What is the main function of bacteriorhodopsin in Haloarchaea?

Ion pumping for energy production Signup and view all the answers

Which group of hyperthermophiles oxidizes iron pyrite ore and generates concentrated sulfuric acid?

Ferroplasma Signup and view all the answers

What is the molecular adaptation seen in Archaea to cope with high salt environments?

High GC content in DNA Signup and view all the answers

What modification do archaeal phospholipids have that distinguishes them from bacterial and eukaryotic phospholipids?

Ether link Signup and view all the answers

Why can some archaea grow at higher temperatures than other forms of life?

Presence of terpenoid chains with methyl branches Signup and view all the answers

What strengthens the membrane of extreme hyperthermophiles living at 110°C?

Methyl branch extensions Signup and view all the answers

In archaeal membrane lipids, what is the purpose of terpenoids derived from isoprene?

Stiffen the membrane by limiting movement Signup and view all the answers

What unique structure do some species of archaea form by linking terpenoid chains at the tails in their membranes?

Tetrahedral monolayers Signup and view all the answers