Chapter 4 Assignment

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

at a temperature of 90oC

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

hami (Archaea have been found to make many unique structures not found in bacteria or eukaryotes.)

A cell morphology unique to archaea is ______

square

Label the following figure with the appropriate attributes for bacterial and archaeal membranes.

Bacteria and archaea each have unique characteristics associated with their membranes.

peptidoglycan

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

Bacteria

-Hollow flagella -Lipids with fatty acids attached to glycerol by ester bonds -Flagellar rotation powered by proton motive force -Cell envelopes with peptidoglycan

Examine the figure which represents 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. (A linear, unsaturated fatty acid attached to glycerol by an ester linkage would derive from a bacterium.)

Archaea

-produce hami and cannulae -cell envelope often contains an s-layer -chromosome associated with histones -membranes can be monolayers or bilayers

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

ABC transport

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.

Archaella and bacterial flagella have some characteristics in common and some features unique to each cell type. Complete the following paragraph to compare and contrast the flagella of archaea and bacteria in terms of structure and function.

Archaella are solid Correct, as opposed to their bacterial counterparts which are hollow. Archaella have a marked similarity to the bacterial Type IV pili and are assembled by the addition of flagellin subunits to the base. Archaella are thinner than bacterial flagella. In archaea, flagellar rotation is driven by ATP hydrolysis

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.

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 (An S-layer in the cell envelope is a good indication that an organism is an archaeon.)

Check all of the structures associated with archaeal cells.

Cannulae Flagella Hami Pili

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.

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.

Pseudomurein

L-amino acids in its cross-links contain N-acetyl talosaminuronic acid B(1->3) gylcosidic bonds

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

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

Match each of the following archaeal cell envelope components with its biochemical composition.

Pseudomurein: Polysaccharide S-layer: Protein Plasma membrane: Lipid

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

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

Drag the labels to complete each of the sentences that discuss the differences between bacterial and archaeal cells.

While there are many similarities between bacteria and archaea, recognition of their differences resulted in them being sorted into entirely different taxa, rather than being characterized as "prokaryotes." The most notable differences are in the cell envelope composition. Bacteria have well-defined cell walls, characterized as being either Gram-positive or Gram-negative, whereas archaea lack peptidoglycan, most having instead a(n) S-layer and some having no cell wall at all. Significant differences are present in the cell membranes of bacteria and archaea; bacteria always have a phospholipid bilayer,, whereas the membranes of some archaea exist as a monolayer, usually depending on their habitat and the need to maintain fluidity. In those organisms that are motile, the structures of bacterial flagella and archaella differ significantly. Archaella are thinner than bacterial flagella, they are not hollow, and are powered by ATP hydrolysis.

Archaeal pili differ from bacterial pili due to the presence of _____

a central lumen (Archaeal pili have some characteristics in common with bacterial pili and some characteristics that are unique.)

An external structure unique to archaea are the _______

cannulae