26. Prokaryotes

Which of the following groups of prokaryotes is classified as a member of the domain Archaea?

Which subgroup of proteobacteria contains many species that are closely associated with eukaryotic hosts in mutualistic or parasitic relationships?

Portions of the genomes of certain prokaryotic species are very similar to portions of the genomes of distantly related prokaryotes. The process that most likely accounts for this genetic similarity is __________.

Which group of bacteria is unusual in that they lack peptidoglycan in their cell walls?

Prokaryotes found inhabiting the Great Salt Lake would be __________.

Which clade of archaea includes most of the extreme thermophiles?

Scientists hypothesize that the O157:H7 strain of E. coli is so different from the K-12 strain because of __________.

Which of the following is a difference between bacteria and archaea?

Which of the following statements is not true? a. Archaea and bacteria have different membrane lipids. b. The cell walls of archaea lack peptidoglycan. c. Only bacteria have histones associated with DNA. d. Only some archaea use CO2 to oxidize H2, releasing methane.

On examining cells under a microscope, you notice that they occur singly and have no evidence of a nucleus. These cells must belong to a a.domain Eukarya; b. domain Bacteria; c. domain Archaea; d. the Protista; e. more than one of the above could be correct

Which of the following prokaryotes is not pathogenic? a. Chlamydia b. Rhizobium c. Streptococcus d. Salmonella

The traditional tree of life (shown above) presents the three domains as distinct, monophyletic lineages. However, other hypotheses propose different views on the relationships among the Archaea, Bacteria, and Eukarya. In particular, the two-domain hypothesis—or eocyte hypothesis—is emerging as a well-supported alternative to the three-domain hypothesis. The eocyte hypothesis, illustrated below, suggests that eukaryotes evolved from eocytes (also known as the Crenarchaeota—a major lineage of the Archaea). Resolving the relationships among these ancient lineages is difficult, but it has profound implications on our understanding of the origin of eukaryotic cells. Early ideas on the classification of life recognized all organisms as belonging to one of two fundamental lineages—prokaryotes or eukaryotes. Is this view compatible with either of the hypotheses illustrated here? Explain.

The traditional tree of life (shown above) presents the three domains as distinct, monophyletic lineages. However, other hypotheses propose different views on the relationships among the Archaea, Bacteria, and Eukarya. In particular, the two-domain hypothesis—or eocyte hypothesis—is emerging as a well-supported alternative to the three-domain hypothesis. The eocyte hypothesis, illustrated below, suggests that eukaryotes evolved from eocytes (also known as the Crenarchaeota—a major lineage of the Archaea). Resolving the relationships among these ancient lineages is difficult, but it has profound implications on our understanding of the origin of eukaryotic cells. Other hypotheses for the tree of life present the Archaea as the ancestors to all other organisms. Sketch a phylogenetic tree that presents Bacteria and Eukarya as more closely related to each other than to Archaea, and that has Archaea as a sister group to Bacteria and Eukarya.

The traditional tree of life (shown above) presents the three domains as distinct, monophyletic lineages. However, other hypotheses propose different views on the relationships among the Archaea, Bacteria, and Eukarya. In particular, the two-domain hypothesis—or eocyte hypothesis—is emerging as a well-supported alternative to the three-domain hypothesis. The eocyte hypothesis, illustrated below, suggests that eukaryotes evolved from eocytes (also known as the Crenarchaeota—a major lineage of the Archaea). Resolving the relationships among these ancient lineages is difficult, but it has profound implications on our understanding of the origin of eukaryotic cells. Evaluate this statement: According to the two-domain hypothesis, all members of the domain Archaea are prokaryotes and therefore lack membrane-bound nuclei.

The traditional tree of life (shown above) presents the three domains as distinct, monophyletic lineages. However, other hypotheses propose different views on the relationships among the Archaea, Bacteria, and Eukarya. In particular, the two-domain hypothesis—or eocyte hypothesis—is emerging as a well-supported alternative to the three-domain hypothesis. The eocyte hypothesis, illustrated below, suggests that eukaryotes evolved from eocytes (also known as the Crenarchaeota—a major lineage of the Archaea). Resolving the relationships among these ancient lineages is difficult, but it has profound implications on our understanding of the origin of eukaryotic cells. What other types of evidence or features might be used to ascertain whether the tree of life is best represented according to the three-domain or the eocyte hypothesis?