Question 1

Some archaeons are symbionts in animal digestive tracts.

Accepted Answer

Some archaeons, such as Methanobrevibacter smithii, are known symbionts in the digestive tracts of animals, where they help break down complex carbohydrates and produce methane gas.

Question 2

Bacterial and archaeal ribosomes are known as _____ ribosomes,based on their sedimentation coefficient.

Accepted Answer

Bacterial and archaeal ribosomes are known as either 70S ribosomes or simply prokaryotic ribosomes based on their sedimentation coefficient, which is the sum of the sedimentation coefficients of their subunits (50S and 30S). 80S ribosomes are found in eukaryotes.

Question 3

_______ are the site of protein synthesis in the cell.

Accepted Answer

Ribosomes

Question 4

Methanogens may contribute to the greenhouse effect and global warming due to methane production.

Accepted Answer

Methanogens are microorganisms that produce methane during their metabolic processes. Methane is a potent greenhouse gas that can contribute to global warming by trapping heat in the atmosphere. As such, methanogens can have an impact on the environment and climate.

Question 5

The DNA of some archaeons is stabilized by association with archaeal histone proteins forming particles resembling eukaryotic nucleosomes.

Accepted Answer

This statement is true. Some archaeons have histone proteins that help to stabilize their DNA, forming structures similar to nucleosomes found in eukaryotes.

Question 6

The hydrocarbons found in the membranes of archaea are identical to those found in bacteria.

Accepted Answer

The hydrocarbons found in the membranes of archaea are not identical to those found in bacteria. Archaeal membranes contain ether linkages while bacterial membranes contain ester linkages. This structural difference contributes to the unique properties and stability of archaeal membranes.

Question 7

Which statement correctly describes archaeal cell walls?

Accepted Answer

Archaeal cell walls can have a variety of different structures, depending on the specific type of archaeon. Some have an outer layer of complex polysaccharide, while others have an outer layer of protein. Peptidoglycan is not typically found in archaeal cell walls. Therefore, the best choice is D, which states that some archaeal cell walls have an outer layer of complex polysaccharide and some have an outer layer of protein.

Question 8

Some archaeal cells lack a cell wall.

Accepted Answer

Some archaeal cells, such as those belonging to group Thermoplasma, do not have a cell wall. Instead, they have a plasma membrane that is stabilized by unique lipids called "archaeols".

Question 9

External structures that are found in Archaea but not Bacteria are _________.

Accepted Answer

Hami are unique hair-like structures found on the surface of some Archaea that allow them to attach to surfaces, including other organisms. They are not found in Bacteria. Pili and flagella are present in both Archaea and Bacteria, but the structure and function may differ between the two domains. Peptidoglycan is a component of the cell wall found in most bacteria but not Archaea.

Question 10

Which of the following is not true about archaeal ribosomes?

Accepted Answer

Archaeal ribosomes are known to be 70S like bacterial ribosomes, and they may possess ribosome binding sites homologous to bacterial Shine-Dalgarno sequences. However, their antibiotic sensitivities are not identical to those of bacteria. Some antibiotics may affect archaeal ribosomes differently from bacterial ribosomes.

Question 11

Archaeal flagella are superficially similar to bacterial flagella,although archaeal flagella are much thicker than bacterial flagella.

Accepted Answer

Archaeal flagella are actually thinner than bacterial flagella, not thicker.

Question 12

The primary lipid components of the membranes of extreme thermophiles are

Accepted Answer

Extreme thermophiles have unique membrane lipids called 40 carbon diglycerol tetraethers, which help stabilize the membrane at high temperatures. These lipids have two hydrocarbon chains, each made up of 20 carbons, and are connected by glycerol. Sulfolipids are found in some but not all thermophiles, and cholesterol is not found in prokaryotic membranes. 20 carbon diglycerol diethers are found in some but not all thermophiles, including mesophilic ones.

Question 13

A feature unique to some archaeal plasma membranes is that they may

Accepted Answer

Some archaeal plasma membranes consist of a lipid monolayer, which is unique compared to the lipid bilayer found in most other cells. This helps them to maintain stability and function in extreme environments like high temperatures or low pH levels.

Question 14

A(n)__________ layer is a layer of protein or glycoprotein that exhibits a pattern resembling floor tiles.

Accepted Answer

The answer of A(n)__________ layer is a layer of protein...

Question 15

Cell walls of most Archaea and bacteria contain peptidoglycan.

Accepted Answer

Most Archaea do not have cell walls containing peptidoglycan; instead, their cell walls are often composed of other polymers such as pseudopeptidoglycan. Bacteria, on the other hand, typically have cell walls that contain peptidoglycan.

Question 16

_______ is a peptidoglycan-like molecule found in the cell walls of some archaea.

Accepted Answer

The answer of _______ is a peptidoglycan-like molecule found in...

Question 17

Molecules or regions of molecules that readily interact with water are said to be __________,whereas molecules or regions of molecules that are insoluble in water or do not readily interact with water are said to be hydrophobic.

Accepted Answer

The answer of Molecules or regions of molecules that readily...

Question 18

Many archaeal genomes include chromosomes and plasmids.

Accepted Answer

Many archaeal genomes have been found to contain both chromosomes and plasmids, which are small circular DNA molecules that replicate independently of the chromosomes. Plasmids often carry beneficial genes, such as antibiotic resistance or metabolic pathways, and can be passed between cells or shared within a population through horizontal gene transfer.

Question 19

Unlike members of the Bacteria,most archaeans have linear chromosomes.

Accepted Answer

Both bacteria and archaea can have circular or linear chromosomes. The shape of their chromosomes is not a defining characteristic to differentiate between the two domains.

Question 20

A peptidoglycan-like polymer found in the cell walls of some Archaea is called __________.

Accepted Answer

The answer of A peptidoglycan-like polymer found in the cell...

Quiz 4: Archaeal Cell Structure