BIO 4302 CH 4

Which cellular shape is seen among members of domain Bacteria that is not found among the domain Archaea?

Spiral or corkscrew shapes

You are working with a newly described microorganism that has flagella that are solid, 10 nm in diameter, and composed of more than one type of flagellin subunit. Based on the type of flagella, which type of organism is this?

archaea

Diglycerol tetraether lipids _________.

are a characteristic feature of thermophilic Archaea

Archaea with a plasma membrane composed of a tetraether monolayer would most likely be found __________.

at a temperature of 90oC

Archaeal membranes contain which of the following lipids?

phospholipids, sulfolipids, glycolipids

Which of the following structures are external to both bacterial and archaeal cells?

pili

what is the biochemical composition of lipids?

plasma membrane

External structures that are found in archaea but not bacteria are _________.

hami

Some archaea have been observed to form tubelike structures with tiny grappling hooks at the ends. These tubelike structures are called _________.

hami

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 __________.

hydrophilic, hydrophobic

Archaeal cell walls _________.

lack murein and D-amino acids

You are studying a newly discovered prokaryotic microorganism and are attempting to determine whether it will be classified in the domain Bacteria or in the domain Archaea. All of the following would be helpful in making that distinction except _________. A. sequence of small subunit ribosomal RNA B. type of membrane lipids C. presence or absence of peptidoglycan in cell walls D. presence or absence of double-stranded circular DNA genome

presence or absence of double-stranded circular DNA genome

what is the biochemical composition of polysaccharides?

pseudomurein

_______ are the site of protein synthesis in the cell.

ribosomes

Archaella are _________, as opposed to their bacterial counterparts which are ________.

solid; hollow

A cell morphology unique to archaea is __________.

square

While there are many similarities between bacteria and archaea, recognition of their differences resulted in them being sorted into entirely different _________, rather than being characterized as "prokaryotes."

taxa

Archaella are ________ than bacterial flagella.

thinner

Considering the diversity of cell envelopes and their components in bacterial and archaeal cells, which of the following statements are correct?

- All cell envelopes require a membrane. - A periplasm layer may be found in the cell envelopes of both Gram-positive bacteria and Gram-negative bacteria.

Select all the characteristics that apply to archaea.

- Archaea have histones associated with their chromosome. - Archaea have multiple copies of chromosomes throughout their life cycle. - Archaea have inclusions such as glycogen granules and gas vacuoles. - Archaea contain ribosomal proteins not found in bacteria or eukaryotes.

Which of the following contribute(s) to the differences between the members of the Domain Archaea and the Domain Bacteria?

- Archaea lack muramic acid. - Archaea have isopranyl glycerol ethers rather than fatty acid esters in their membrane lipids. - Archaea differ from bacteria in their tRNA composition, ribosome structure, and antibiotic sensitivity.

Check all the characteristics that would differentiate an archaellum from a bacterial flagellum.

- Archaella are solid, while bacterial flagella are hollow. - An archaellum is powered by ATP, while a bacterial flagellum is powered by the proton motive force.

Considering the diversity of membranes and their components in bacterial and archaeal cells, which of the following statements are correct about membranes in BOTH domains?

- Cell membranes require a hydrophobic interior and two hydrophilic surfaces to be an effective barrier between the cell cytoplasm and its external environment. - Membrane lipids are covalently bonded to glycerol. - Membrane thickness is equivalent to a 40-carbon hydrocarbon chain either in the form of two C20 bilayers, or a single C40 monolayer.

Characteristics of Peptidoglycan

- D-amino acids in its cross-links - contains N-acetyl muramic acid - B(1-->4) glycosidic bonds

Some archaea are polyploid. Which of the following statements are TRUE regarding archaeal polyploidy?

- Each chromosome in a polyploid organism has an identical copy of the organism's genetic information. - A mutation that occurs in one chromosome may be phenotypically "rescued" by wild type alleles on other chromosomes.

Which of the following statements are correct about archaeal histones and nucleosomes?

- Histones may help stabilize the chromosome against heat denaturation in thermophiles. - Histones are an alternative to supercoiling for helping to compact the archaeal chromosome into the cytoplasm. - Nucleoid-associated proteins are found in all organisms, and therefore must play an essential role in chromosome structure.

Characteristics of Pseudomurein

- L-amino acids in its cross-links - contains N-acetyltalosaminuronic acid - B(1-->3) glycosidic bonds

Considering the variations in ribosomes found in bacterial and archaeal cells, which of the following statements are correct about ribosomes in both domains?

- Ribosomes are composed of two subunits, a large 50S subunit and a small 30S subunit. - Ribosomes are composed of RNA and protein. - Ribosomal proteins from bacteria and archaea are also found in eukaryotes.

Examine the accompanying figure (molecule 5) of two lipid molecules arranged in a bilayer. Choose each statement that is correct regarding this structure.

- The hydrocarbon chains in this lipid are attached to glycerol by an ester linkage (indicated by the letter A). - The hydrocarbon chain (indicated by the letter B) is best described as linear and unsaturated. - This structure most likely derives from a bacterium.

In order to distinguish them from bacterial flagella, archaeal flagella have been renamed as archaella because _________.

- archaean flagella are composed of more than one type of flagellin subunit - they are more slender than bacterial flagella - some archaeon flagella don't have hooks - archaean flagella are solid and not hollow

Check all of the structures associated with archaeal cells.

- cannulae - flagella - hami - pili

Characteristics of Bacteria

- lipids with fatty acids attached to glycerol by ester bonds - cell envelopes with peptidoglycan - hollow flagella - flagellar rotation powered by proton motive force

Characteristics of Archaea

- membranes can be monolayers or bilayers - cell envelope often contains an S-layer - chromosome associated with histones - membrane lipids contain isoprenic hydrocarbons - produce hammy and cannulae

The Archaea generally lack which of the following that are normally found in Gram-negative bacteria?

- outer membrane - a complex peptidoglycan network - lipopolysaccharide

Evaluate the statements below and choose those that correctly apply to the factors governing nutrient supply in archaea.

- the need to store nutrients that are in short supply requires the use of active transport to move molecules against their concentration gradient - both ABC and symport/antiport mechanisms of transport are used by archaea to transport nutrients into the cell - often called "extremophiles", archaea may inhabit a nutrient-poor niche necessitating an accumulation mechanism

The primary lipid components of the membranes of extreme thermophiles are _________.

40 carbon diglycerol tetraethers

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

70S

An archaeon in a nutrient-poor environment is most likely to use _________ for nutrient uptake.

ABC transport

In archaea, flagellar rotation is driven by ___________________.

ATP hydrolysis

If you found a microbe with an S-layer as the major component of its cell wall, how would you identify this microbe?

As an archaeon

Penicillin inhibits bacterial growth by preventing the cross-linking during peptidoglycan synthesis. Why does penicillin not inhibit growth of archaeal cells?

Most archaeal cells have a cell wall, but it is not composed of peptidoglycan.

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

Pseudomurein

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

S layer

what is the biochemical composition of protein?

S-layer

Which of the following is the most unique aspect of archaeon cell envelopes?

Some archaeons have lipid monolayers in their plasma membrane.

Which statement correctly explains the Gram-stain reaction of archaeal cells?

Some are Gram-positive and some are Gram-negative due to the diverse chemical structure.

Which statement correctly describes archaeal cell walls?

Some have an outer layer of complex polysaccharide and some have an outer layer of protein.

Select the correct statement about archaeal ribosomes.

The chemical components of archaean ribosomes are more similar to those of eukaryotic ribosomes than to those of bacterial ribosomes.

Which of the following is not true about archaeal ribosomes?

They have similar antibiotic sensitivities to those of bacteria

One type of archaeon, Haloquadratum walsbyi, is shaped like a postage stamp with dimensions of 2 µm x 3 µm x 0.25 µm. What advantage would this shape provide?

This shape increases the surface to volume ratio enabling more efficient nutrient uptake.

Archaella have a marked similarity to the bacterial ___________ and are assembled by the addition of flagellin subunits to the __________.

Type IV pili; base

Archaeal pili differ from bacterial pili due to the presence of _________.

a central lumen

Which type of membrane transport is most important for nutrient acquisition in nutrient poor environments?

active transport

Archaea often live in nutrient-poor environments. In order to ensure survival, they must __________.

accumulate nutrients inside the cell at higher concentrations than the external environment, which requires active transport mechanisms

A fundamental difference between bacterial and archaeal membranes is that __________.

bacterial membranes are always comprised of phospholipid bilayers, whereas archaeal membranes can be bilayers or monolayers

Significant differences are present in the cell membranes of bacteria and archaea; bacteria always have a phospholipid ____________, whereas the membranes of some archaea exist as a ____________, usually depending on their habitat and the need to maintain fluidity.

bilayer; monolayer

An external structure unique to archaea are the __________.

cannulae

__________ are hollow tube-like structures that hold some archaeal daughter cells together after cell division while___________ are grappling hook-like structures that appear to attach archaeal cells to surfaces.

cannulae; hami

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

consist of a lipid monolayer

The cell membranes of archaeons that lack a cell wall are strengthened by _________.

diglycerol tetraethers

The most notable differences are in the cell ___________ composition. Bacteria have well-defined cell walls, characterized as being either Gram-positive or Gram-negative, whereas archaea lack ______________, most having instead an ____________ and some having no cell wall at all.

envelope; peptidoglycan; S-layer

Archaeal and bacterial pili are identical in structure and function.

false

Archaeal flagella (archaella) are superficially similar to bacterial flagella, although archaella are much thicker than bacterial flagella.

false

Archaeons power their flagella by proton motive force (PMF), whereas bacteria empower their flagella by ATP hydrolysis.

false

Cell walls of most archaea and bacteria contain peptidoglycan.

false

In terms of membrane lipids, the plasma membranes of archaeons are more similar to those of the eukaryotes than to membranes of bacteria.

false

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

false

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

false

In those organisms that are motile, the structures of bacterial flagella and archaella differ significantly. Archaella are _________ than bacterial flagella, they are not hollow, and are powered by ______________.

thinner; ATP hydrolysis

Many archaeal genomes include chromosomes and plasmids.

true

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

true

Some archaeal cells lack a cell wall.

true

Some archaeons are symbionts in animal digestive tracts.

true

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

true