Chapter 21: Nonproteobacterial Gram-negative Bacteria
Mollicutes have the smallest genomes among bacteria. The genome ranges in size from ______.
0.7 to 1.7 million base pairs
What function do organisms of the genus Bacteroides perform in the mammalian digestive tract?
They degrade complex carbohydrates.
Which two of these statements are correct regarding the green nonsulfur bacteria?
They grow in association with cyanobacteria. They contain chlorosomes as the site of photosynthesis.
How do spirochete periplasmic flagella move?
They rotate
True or false: Bacteria of the phylum Bacteroidetes are common in sewage treatment plants where they contribute to the digestion of macromolecules.
True
True or false: Deinococcus species can easily tolerate doses of radiation that would be lethal to humans.
True
True or false: Eukaryotic chloroplasts are believed to have evolved from endosymbiotic cyanobacteria.
True
True or false: Periplasmic flagella permit spirochetes to move across solid surfaces.
True
When cyanobacterial filaments are deprived of nitrate and ammonia, what proportion of cells differentiate into heterocysts?
5-10%
Aquifex species are hyperthermophiles. Their optimal growth temperature is ______.
85°C
In which two of the following environments might cyanobacteria be found?
Alkaline hot springs Freshwater lakes
Which two of the following organisms are genera of bacterial hyperthermophiles?
Aquifex Thermotoga
In which domains would you find thermophiles?
Archaea; Bacteria
If a spirochete cell is modeled as a cylinder, where do the axial fibrils attach to the cell?
At both ends of the cylinder
In which domains would you find hyperthermophiles?
Bacteria Archaea
Which three of the following reproductive strategies are found in cyanobacteria?
Budding Binary fission Fragmentation
Which two of the following terms best describe the movement of spirochete cells, as mediated by periplasmic flagella?
Corkscrew Crawling
What triggers the differentiation of cyanobacterial cells to heterocysts?
Depletion of nitrogen sources
True or false: Phototrophic capture of energy is always linked to CO2 fixation.
False
Which of the following best describes peptidoglycans in members of the Planctomycetes-Verrucomicrobia-Chlamydiae superphylum?
Genes encoding peptidoglycan synthesis are found in the genomes. Peptidoglycan has been demonstrated in at least one species.
Which of the following is a property of spirochetes?
Gram negative
Which two of the following pathways are found in mycoplasmas?
Lactic acid fermentation Embden-Meyerhof pathway
Most species of Deinococcus are ______.
Mesophilic
Aquifex species generate energy by oxidizing hydrogen, thiosulfate, and sulfur, and they use oxygen as the terminal electron acceptor. These organisms are predicted to grow as ______.
aerobes
The annamoxosome is a compartment for anaerobic ______.
ammonia oxidation
Some genera in the Planctomycetes contain an intracellular compartment for the anaerobic oxidation of ammonia called the
anammoxosome
Anaerobic methane oxidation is carried out by ______.
archaea
Mycoplasmas can generate energy from arginine in the series of reactions illustrated in the image. The first enzyme in this pathway catalyzes the removal of ammonia from arginine and is called ______.
arginine deaminase
Aerobic methane oxidation is carried out by ______.
bacteria
The axial fibrils of spriochetes are located ______.
between the cell wall and the outer sheath
The rapid reproduction of some cyanobacteria to dominate freshwater bodies (shown in this image) is called a cyanobacterial
bloom
Cyanobacteria were formerly known as ______.
blue-green algae
In microbial methane oxidation, the methane is used as a source of ______.
carbon
The enzymes responsible for CO2 fixation in cyanobacteria are located in microcompartments called
carboxysomes
The structures indicated by the red arrow are ______.
carboxysomes
Mycoplasmas require sterols as components of the ______.
cell membrane
All known members of the phylum Bacteroidetes are ______.
chemoheterotrophs
Chloroplasts are thought to have evolved from ______.
cyanobacteria
The largest and most diverse group of photosynthetic bacteria are the ______.
cyanobacteria
Some species of cyanobacteria reproduce by forming akinetes. These are ______.
dormant cells that resist desiccation
The cyanobacterial photosynthetic apparatus most closely resembles that of ______.
eukaryotes
When Deinococcus cells are exposed to radiation, which process is responsible for fragmenting the genome?
generation of radical oxygen species
The common name for Mollicutes is
mycoplasmas
What function is performed by heterocysts in filamentous cyanobacteria?
nitrogen
What proportion of the bacteria isolated from human feces are Bacteroides?
30%
Chlamydiae are responsible for which two human illnesses?
Nongonococcal urethritis Preventable blindness
Which of these statements is correct regarding the green nonsulfur bacteria?
Only some members of this group are green and only some use sulfur.
Which chemical is used as the terminal electron acceptor by Aquifex species?
Oxygen
Which two molecules are found in phycobilisomes?
Phycocyanin Proteins
Organisms in which genus of cyanobacteria occupy the open ocean below 100 meters and harvest blue-violet light?
Prochlorococcus
About one-third of global CO2 fixation is performed by two marine cyanobacterial genera, ______.
Prochlorococcus and Synechococcus
Aquifex species fix CO2 by the ______.
Reductive Citric Acid Cycle
Which two of the following characteristics are shared by mycoplasmas?
Small genome size Simplified metabolic pathways
Which of the following describe the cellular morphology and arrangement of Deinococcus?
Spherical, in pairs or tetrads
Organisms in which genus of cyanobacteria occupy the upper 25 meters of the open ocean and harvest white and blue-green light?
Synechococcus
What is the molecular consequence of exposure to high levels of radiation to the Deinococcus genome?
The genome is fragmented to hundreds of pieces.
The structure indicated by the arrow in this image of a filamentous cyanobacterium is a ______.
heterocyst
When filamentous cyanobacteria reproduce by fragmentation, they generate small motile filaments called
hormogonia
When filamentous cyanobacteria reproduce by fragmentation, they generate small motile filaments called ______.
hormogonia
Which two of the following are used as electron sources by green sulfur bacteria?
hydrogen sulfur
Bacteria in the phylum Fusobacteria ______.
inhabit anoxic sediments and oral and intestinal tracts of mammals and insects are obligate or facultative anaerobes use amino acids and proteins as their primary energy source
Which three of the following describe organisms of the genus Chlamydia?
intracellular parasite Gram negative human pathogen
Which two properties unify the organisms classified as Tenericutes?
no synthesis of peptidoglycan precursors absence of a cell wall
Green sulfur bacteria are ______.
obligate anaerobes
To be used as a carbon source, methane must be ______.
oxidized
Which of the following traits are shared by cyanobacterial photosynthesis and eukaryotic photosynthesis?
oxygenic photosynthesis presence of chlorophyll a
Which two types of microbes are considered to be photosynthetic?
photoautotrophs photoheterotrophs
The phycobilisome arrangement of a core allophycocyanin and stacks of other pigments enables efficient transfer of energy to ______.
photosystem II
Sterols are essential in the cell membranes of mycoplasmas to ______.
promote osmotic stability
Fusobacterium species exhibit a characteristic ______ shape.
spindle, or football
Most Mollicutes require which of the following for growth?
sterols
Consider the superphylum that includes Planctomycetes, Verrucomicrobia, Chlamydiae, and four others. Some genera within each of these phyla synthesize sterols and lack the cell division protein FtsZ. Because these features are not present in all representatives of the superphylum, it is thought ______.
the last common ancestor had all these characteristics, which were subsequently lost by some members
A consequence of the small genome size in Mollicutes is that ______.
they cannot synthesize many macromolecules
Several species of Mollicutes have fewer than 1,000 genes in their genome. This suggests that ______.
this is the minimum size needed for free-living bacteria
