Prokaryote Cell Structures

Gram-negative bacteria have __________ peptidoglycan than gram-positive cells, and their cell walls are __________ complex structurally.

A gram-negative cell wall consists of __________.

Bacteria that __________ tend to have abundant internal membranes.

Bacterial flagella have a very complex structure composed of 42 distinct proteins. What is the most likely explanation for the evolution of these complex structures?

The bacteria that cause tetanus can be killed only by prolonged heating at temperatures considerably above boiling. This suggests that these bacteria __________.

Using the figure below, describe the stages that may have led to the origin of life.

Explain how each of the following characteristics contributes to the success of prokaryotes: cell wall, capsule, flagella, fimbriae, endospores.

Unlike plant cell walls that contain cellulose, bacterial cell walls are composed of           .

Unlike plant cell walls that contain cellulose, bacterial cell walls are composed of           .

A new organism has been discovered. Tests have revealed that it is unicellular, is autotrophic, and has a cell wall that contains peptidoglycan. Based on this evidence, it should be classified as a(n) a. alga. b. archaean. c. protist. d. bacterium.

The bacteria that cause tetanus can be killed only by prolonged heating at temperatures considerably above boiling. This suggests that tetanus bacteria a. have cell walls containing peptidoglycan. b. secrete endotoxins. c. are autotrophic. d. produce endospores.

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. The Bacteria and Archaea both include microscopic prokaryotes that lack membrane-bound nuclei. What criteria have led to the classification of these two groups as separate domains?

Why is salt a good preservative to use for foods such as pork and fish?

Plasmids __________.

How is it possible that as many as 9 million mutations can arise each day in the population of E. coli inhabiting one human?

In the absence of meiosis and sexual reproduction, what general process allows genetic recombination among prokaryotes?

Which of the following statements about transformation is true?

An F⁺ bacterial cell __________.

Which of the following is/are true about R plasmids?

Genetic variation in bacterial populations cannot result from a. transduction. b. conjugation. c. mutation. d. meiosis.

What has metagenomic analysis allowed researchers to do for the first time? a. sample organisms from an environment and grow them under defined conditions in the lab b. isolate organisms from an environment and sequence their entire genome c. study organisms that cannot be cultured (grown in the lab) d. identify important morphological differences among species

What has metagenomic analysis allowed researchers to do for the first time? a. sample organisms from an environment and grow them under defined conditions in the lab b. isolate organisms from an environment and sequence their entire genome c. study organisms that cannot be cultured (grown in the lab) d. identify important morphological differences among species

Bacteria are able to divide on a faster schedule than eukaryotic cells. Some bacteria can divide every 20 minutes, while the minimum time required by eukaryotic cells in a rapidly developing embryo is about once per hour, and most cells divide much less often than that. State at least two testable hypotheses explaining why bacteria can divide at a faster rate than eukaryotic cells.

Organisms that use light for their energy source and CO₂ for their carbon source are called __________.

In an experiment, a microbiologist put equal numbers of each of the following organisms into a flask of sterile broth, consisting mostly of sugar and a few amino acids. She then placed the flask in the dark. Which of the organisms would be most likely to survive?

The Desulfovibrio bacterium breaks down organic matter (which it must have) and uses sulfate (not oxygen) as an electron acceptor. As a result, it produces hydrogen sulfide (H₂S), accounting for the "rotten egg" smell of swamp muck. Oxygen is a deadly poison to Desulfovibrio. We would call Desulfovibrio a(n) __________.

Choose the list below that contains the substances required by typical nitrogen-fixing cyanobacteria.

What is the role of heterocysts in a cyanobacterial filament?

Biofilms are an example of __________.

Which statement about prokaryotes is true?

Prokaryotes are completely indispensable to which chemical cycle?

A type of ecological relationship called __________ involves one organism living at the expense of another organism.

Which of the following statements about cyanobacteria is/are true?

Ticks that live on deer and field mice are responsible for spreading the bacterium __________, which causes __________.

Which example below is a correct statement about Bacteroides thetaiotaomicron, a bacterium that lives in the human intestines?

Which statement is true regarding cholera?

What do some photosynthetic bacteria use as a source of electrons instead of water? a. oxygen (O2) b. hydrogen sulfide (H2S) c. organic compounds (e.g., CH3COO−) d. nitrate (NO3-)

What do some photosynthetic bacteria use as a source of electrons instead of water? a. oxygen (O2) b. hydrogen sulfide (H2S) c. organic compounds (e.g., CH3COO−) d. nitrate (NO3-)

Photoautotrophs use a. light as an energy source and CO2 as a carbon source. b. light as an energy source and methane as a carbon source. c. N2 as an energy source and CO2 as a carbon source. d. CO2 as both an energy source and a carbon source.

What are organisms called that use inorganic compounds as electron donors in cellular respiration? a. phototrophs b. heterotrophs c. organotrophs d. lithotrophs

What are organisms called that use inorganic compounds as electron donors in cellular respiration? a. phototrophs b. heterotrophs c. organotrophs d. lithotrophs

Which of the following statements is true? (A)Archaea and bacteria have identical membrane lipids. (B)The cell walls of archaea lack peptidoglycan. (C)Prokaryotes have low levels of genetic diversity. (D)No archaea are capable of using CO2 to oxidize H2, releasing methane.

In terms of nutrition, autotrophs are to heterotrophs as a. kelp are to diatoms. b. archaea are to bacteria. c. slime molds are to algae. d. algae are to slime molds.

Which of the following involves metabolic cooperation among prokaryotic cells? a. binary fission b. endospore formation c. biofilms d. photoautotrophy

Which of the following describes a bacterium that lives in the human intestine and causes disease? (A)commensalist (B)decomposer (C)gut mutualist (D)symbiotic pathogen

Bacteria perform the following ecological roles. Which role typically does not involve symbiosis? a. skin commensalist b. decomposer c. gut mutualist d. pathogen

Biologists often use the term “energy source” as a synonym for “electron donor.” Why?

Biologists often use the term “energy source” as a synonym for “electron donor.” Why?

Explain why prokaryote populations can adapt rapidly to changes in their environment.

Streptococcus mutans obtains energy by oxidizing sucrose. This bacterium is abundant in the mouths of Western European and North American children and is a prominent cause of cavities. The organism is virtually absent in children from East Africa, where tooth decay is rare. Propose a hypothesis to explain this observation. Outline the design of a study that would test your hypothesis.

Streptococcus mutans obtains energy by oxidizing sucrose. This bacterium is abundant in the mouths of Western European and North American children and is a prominent cause of cavities. The organism is virtually absent in children from East Africa, where tooth decay is rare. Propose a hypothesis to explain this observation. Outline the design of a study that would test your hypothesis.

Suppose that you’ve been hired by a firm interested in using bacteria to clean up organic solvents found in toxic waste dumps. Your new employer is particularly interested in finding cells that are capable of breaking a molecule called benzene into less-toxic compounds. Where would you go to look for bacteria that can metabolize benzene as an energy or carbon source? How would you design an enrichment culture capable of isolating benzene-metabolizing species?

Suppose that you’ve been hired by a firm interested in using bacteria to clean up organic solvents found in toxic waste dumps. Your new employer is particularly interested in finding cells that are capable of breaking a molecule called benzene into less-toxic compounds. Where would you go to look for bacteria that can metabolize benzene as an energy or carbon source? How would you design an enrichment culture capable of isolating benzene-metabolizing species?

Which of the following experiments could test the hypothesis that bacteria cause ulcers in humans? (Assume each experiment includes a control group.) Explain what evidence would be provided by the results of the experiment. a. Identify the microbes found in the stomachs of ulcer patients. b. Treat a group of ulcer patients with antibiotics. c. Place a group of ulcer patients on a strict low-acid diet. d. Obtain stomach fluid from ulcer patents and feed it to mice.

SCIENTIFIC THINKING Probiotics, foods and supplements that contain living microorganisms, are thought to cure problems of the digestive tract by restoring the natural balance of its microbial community. Sales of these products total billions of dollars a year. Explore the topic of probiotics and evaluate the scientific evidence for their beneficial effects. A good starting point is the website of the U.S. Food and Drug Administration, which regulates advertising claims of health benefits of dietary supplements. U.S. Food and Drug Administration website, www.fda.gov/food/dietary-supplements.

Imagine you are on a team designing a moon base that will be self-contained and self-sustaining. Once supplied with building materials, equipment, and organisms from Earth, the base will be expected to function indefinitely. One of the team members has suggested that everything sent to the base be sterilized so that no bacteria of any kind are present. Do you think this is a good idea? Predict some of the consequences of eliminating all bacteria from an environment.

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?

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.

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.

Evaluate these statements about Koch’s postulates, which are used to establish a causative link between a specific microbe and a specific disease. Select True or False for each statement. T/F The microbe must be present in individuals suffering from the disease and absent from healthy individuals. T/F The microbe must be isolated and grown in pure culture. T/F If organisms from the pure culture are injected into a healthy experimental animal, the disease symptoms should appear. T/F The microbe does not have to be isolated from the experimental animal as long as the disease is present.

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.

Evaluate these statements about Koch’s postulates, which are used to establish a causative link between a specific microbe and a specific disease. Select True or False for each statement. T/F The microbe must be present in individuals suffering from the disease and absent from healthy individuals. T/F The microbe must be isolated and grown in pure culture. T/F If organisms from the pure culture are injected into a healthy experimental animal, the disease symptoms should appear. T/F The microbe does not have to be isolated from the experimental animal as long as the disease is present.

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

Plantlike photosynthesis that releases O2 occurs in a. cyanobacteria. b. archaea. c. gram-positive bacteria. d. chemoautotrophic bacteria.

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?