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BIO 160 > 27. Bacteria and Archaea > Flashcards

27. Bacteria and Archaea Flashcards

1
Q

Key concepts

A

27.1 Structural and functional adaptations contribute to the prokaryotic success
27.2 Rapid production, mutation and genetic recombination promote genetic diversity in prokaryotes
27.3 Diverse nutritional and metabolic adaptations have evolved in prokaryotes
27.4 Prokaryotes have radiated into a diverse set of lineages
27.5 Prokaryotes play crucial roles in the biosphere
27.6 Prokaryotes have both beneficial and harmful impacts on humans

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2
Q

prokaryote

A
  • the single-celled organisms that make up domains Bacteria and Archaea, can thrive in a wide range of extreme environments.
    -Their ability to adapt to a broad range of habitats helps explain why prokaryotes are the most abundant organisms on Earth.
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3
Q

Characteristics enabling prokaryotes to reach huge population sizes and thrive in diverse environments

A
  • small size
  • rapid reproduction
  • mutations
  • diverse adaptations
  • rapid evolution
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4
Q

peptidoglycan

A

-a type of polymer in bacterial cell walls consisting of modified sugars cross-linked by short polypeptides

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5
Q

Gram stain

A
  • a staining method that distinguishes between two different kinds of bacterial cell walls; may be used to help determine medical response to an infection
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6
Q

Gram-positive bacteria

A
  • describing the group of bacteria that have a cell wall that is structurally less complex and contains more peptidoglycan than the cell wall of gram-negative bacteria. Gram-positive bacteria are usually less toxic than gram-negative bacteria.
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7
Q

Gram-negative bacteria

A
  • describing the group of bacteria that have a cell wall that is structurally more complex and contains less peptidoglycan than the cell wall of gram-positive bacteria. Gram-negative bacteria are often more toxic than gram-positive bacteria
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8
Q

capsule

A
  • in many prokaryotes a dense and well-defined layer of polysaccharide or protein that surrounds the cell wall and is sticky protecting the cell and enabling it to adhere to substrates or other cells
  • the sporangium of a bryophyte (moss, liverwort or hornwort)
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9
Q

endospore

A

a thick-coated, resistant cell produced by some bacterial cells when they are exposed to harsh conditions

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10
Q

fimbria

A

a short, hairlike appendage of a prokaryotic cell that helps it adhere to the substrate or to the other cells

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11
Q

pilus

A

in bacteria, a structure that links one cell to another at the start of conjugation; also called a sex pilus or conjugation pilus

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12
Q

taxis

A

an oriented movement toward or away from a stimulus

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13
Q

nucleoid

A

a non-membrane- enclosed region in a prokaryotic cell where its chromosome is located

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14
Q

plasmid

A

a small circular double-stranded DNA molecule that carries accessory genes separate from those of a bacterial chromosome; in DNA cloning, plasmids are used as vectors carrying up to about 10,000 base pairs (10 kb) of DNA. Plasmids are also found in some eukaryotes such as yeasts

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15
Q

transformation

A
  • the process by which a cell in a culture acquires the ability to divide indefinitely, similar to the division of cancer cells
  • a change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA is from a member of a different species transformation results in horizontal gene transfer
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16
Q

transduction

A

a process in which phages (viruses) carry bacterial DNA from one bacterial cell to another. When these two cells are members of different species, transduction results in horizontal gene transfer

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17
Q

conjugation

A

-in prokaryotes the direct transfer of DNA between two cells that are temporarily joined. When the two cells are members of different species, conjugation results in horizontal gene transfer
- in ciliates a sexual process in which two cells exchange haploid micronuclei but do not reproduce

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18
Q

F factor

A

-in bacteria, the DNA segment that confers the ability to form pili for conjugation and associated functions required for the transfer of DNA from donor to recipient. The F factor may exist as a plasmid or be integrated into the bacterial chromosome.

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19
Q

F plasmid

A

the plasmid form of F factor

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20
Q

R plasmids

A

a bacterial plasmid carrying genes that confer resistance to certain antibiotics

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21
Q

Major nutritional modes (Autotroph)

A
  • Photoautroph (light; Photosynthetic prokaryotes (for example, cyanobacteria); plants; certain protists (for example, algae))
    -Chemoautotroph (Inorganic chemicals; Unique to certain prokaryotes (for example, Sulfolobus))
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22
Q

Major nutritional modes (Heterotroph)

A

-Photoheterotroph (light; Unique to certain aquatic and salt-loving prokaryotes (for example, Rhodobacter, Chloroflexus))
-Chemoheterotroph (organic compounds; Many prokaryotes (for example, Clostridium) and protists; fungi; animals; some plants)

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23
Q

obligate aerobe

A

an organism that requires oxygen for cellular respiration and cannot live without it

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24
Q

obligate anaerobes

A

an organism that carries out only fermentation or anaerobic respiration. Such organisms cannot use oxygen and in fact may be poisoned by it.

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25
Q

anaerobic respiration

A

a catabolic pathway in which inorganic molecules other than oxygen accept electrons at the downhill end of electron transport chains

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26
Q

facultative anaerobes

A

an organism that makes ATP by aerobic respiration if oxygen is present but that switches to anaerobic respiration or fermentation if oxygen is not present

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27
Q

nitrogen fixation

A

the conversion of atmospheric nitrogen to ammonia. Biological nitrogen fixation is carried out by certain prokaryotes, some of which have mutualistic relationships with plants.

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28
Q

heterocyst

A

a specialized cell that engages in nitrogen fixation in some filamentous cyanobacteria; also called a heterocyte

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29
Q

biofilm

A

a surface-coating colony of one or more species of unicellular organisms that engage in metabolic cooperation; most known biofilms are formed by prokaryotes

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30
Q

extremophile

A

an organism that lives in environmental conditions so extreme that few other species can survive there. Extremophiles include extreme halophiles (salt lovers) and extreme thermophiles (heat lovers)

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31
Q

extreme halophile

A

an organism that lives in highly saline environment such as the Great Salt Lake or the Dead sea

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32
Q

Extreme thermophiles

A

an organism that thrives in hot environments (often 60-80 degrees celsius or hotter)

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33
Q

methanogens

A

an organism that produces methane as a waste product of the way it obtains energy. All known methanogens are in domain archaea

34
Q

decomposer

A

an organism that absorbs nutrients from nonliving organic material such as corpses, fallen plant material and the wastes of living organisms and converts them to inorganic forms; a detrivore

35
Q

symbiosis

A

an ecological relationship between organisms of two different species that live together in direct and intimate contact

36
Q

host

A

the larger participant in a symbiotic relationship, often providing a home and food source for the smaller symbiont

37
Q

symbiont

A

the smaller participant in a symbiotic relationship, living in or on the host

38
Q

mutualism

A

ecological interaction that benefits individuals of both interacting species

39
Q

commensalism

A

ecological interaction that benefits the individuals of one species but neither harms nor helps the individuals of the other species

40
Q

parasitism

A

ecological interaction in which one organism, the host, which is harmed; some parasites live within the host (feeding on its tissues) while others feed on the host’s external surface

41
Q

pathogen

A

an organism or virus that causes disease

42
Q

exotoxin

A

a toxic protein that is secreted by a prokaryote or other pathogen and that produces specific symptoms, even if the pathogen is no longer present

43
Q

endotoxins

A

a toxic component of the outer membrane of certain gram-negative bacteria that is released only when the bacteria die

44
Q

CRISPR-Cas99 system

A

a technique for editing genes in living cells, involving a bacterial protein called cas9 associated with a guide RNA complementary to a gene sequence of interest

45
Q

bioremediation

A

the use of organisms to detoxify and restore polluted and degraded ecosystems

46
Q

Concept 27.1 summary

A

Many prokaryotic species can reproduce quickly by binary fission, leading to the formation of extremely large populations.

47
Q

Concept 27.2 summary

A

-Because prokaryotes can often proliferate rapidly, mutations can quickly increase a population’s genetic variation. As a result, prokaryotic populations often can evolve in short periods of time in response to changing conditions.
-Genetic diversity in prokaryotes also can arise by recombination of the DNA from two different cells (via transformation, transduction, or conjugation). By transferring advantageous alleles, such as ones for antibiotic resistance, recombination can promote adaptive evolution in prokaryotic populations.

48
Q

Concept 27.3 summary

A

-Nutritional diversity is much greater in prokaryotes than in eukaryotes and includes all four modes of nutrition: photoautotrophy, chemoautotrophy, photoheterotrophy, and chemoheterotrophy.
-Among prokaryotes, obligate aerobes require , obligate anaerobes are poisoned by , and facultative anaerobes can survive with or without .
-Unlike eukaryotes, prokaryotes can metabolize nitrogen in many different forms. Some can convert atmospheric nitrogen to ammonia, a process called nitrogen fixation.
-Prokaryotic cells and even species may cooperate metabolically, including in surface-coating biofilms.

49
Q

Concept 27.4 summary

A

-Molecular systematics is helping biologists classify prokaryotes and identify new clades.
-Diverse nutritional types are scattered among the major groups of bacteria. The two largest groups are proteobacteria and gram-positive bacteria.
-Some archaea, such as extreme thermophiles and extreme halophiles, live in extreme environments. Other archaea live in moderate environments such as soils and lakes.

50
Q

Concept 27.5 summary

A
  • Decomposition by heterotrophic prokaryotes and the synthetic activities of autotrophic and nitrogen-fixing prokaryotes contribute to the recycling of elements in ecosystems.
    -Many prokaryotes have a symbiotic relationship with a host; the relationships between prokaryotes and their hosts range from mutualism to commensalism to parasitism.
51
Q

Concept 27.6 summary

A

-People depend on mutualistic prokaryotes, including hundreds of species that live in our intestines and help digest food.
-Pathogenic bacteria typically cause disease by releasing exotoxins or endotoxins. Horizontal gene transfer can spread genes associated with virulence to harmless species or strains.
-Resistance to multiple antibiotics has evolved in many pathogenic bacteria, a problem of great concern for public health.
-Prokaryotes can be used in bioremediation and production of plastics, vitamins, antibiotics, and other products.

52
Q

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)

A

obligately anaerobic chemoheterotroph

53
Q

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 following organisms would be most likely to survive?

A

Chemoheterotrophic bacteria

54
Q

Which of the following is not one of the most common prokaryotic cell shapes?

A

Cuboidal

55
Q

Bacteria that __________ tend to have abundant internal membranes.

A

are photosynthetic

56
Q

Which of the following characteristics is a reason why a Gram-stain to distinguish gram-positive from gram-negative bacteria is an important tool in a medical diagnosis of a bacterial infection?

A

The cell walls of many gram-negative bacteria are toxic.

The outer membrane of a gram-negative bacterium helps protect it from the body’s defenses.

Certain gram-positive bacteria are resistant to antibiotics.

None of the listed characteristics is a reason why a Gram-stain is important in medicine.

57
Q

Which of the following is a structure that bacteria, archaea, and eukaryotes have?

A

Plasma membrane

58
Q

Bacteria function primarily in which ecological role?

A

Mutualism

Commensalism

Parasitism

Decomposition

59
Q

Plasmids

A

replicate independently of the main chromosome

often contain antibiotic resistance genes

are transferred from one bacterium to another by conjugation

allow bacteria to survive adverse conditions

60
Q

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

A

Chlamydias

61
Q

Which of the following statements about cyanobacteria is true?

A

Some are single cells, whereas others live in filamentous colonies.

They are the only prokaryotes that perform plantlike, oxygenic photosynthesis.

Some species may carry on nitrogen fixation.

It can be said that nitrogen-fixing cyanobacteria are the most self-sufficient of all organisms.

62
Q

What is the function of a bacterial endospore?

A

To facilitate persistence in temporarily harsh environments

63
Q

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

A

Alpha

64
Q

Which of the following mechanisms is/are (a) means of genetic recombination in prokaryotes?

A

Transformation

Transduction

Conjugation

65
Q

Bacteria that use light for their energy source and CO2 for their carbon source are called _

A

photoautotrophs

66
Q

What is a difference between the cell walls of prokaryotes and the cell walls of eukaryotes?

A

The cell walls of prokaryotes are made of molecules different from those comprising the cell walls of eukaryotes.

67
Q

An F+ bacterial cell

A

acts as a donor during conjugation

68
Q

What is the structural feature of gram-positive bacteria that results in their retaining a crystal violet dye stain and thereby being distinguished from gram-negative bacteria in a Gram-stain technique?

A

Gram-positive bacteria have thicker cell walls.

69
Q

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 _

A

horizontal gene transfer

70
Q

Antibiotics administered in human medicine work against bacterial infections by

A

interfering with an aspect of bacterial metabolism or structure that differs from that of eukaryotic cells

71
Q

Some prokaryotes stick to their substrate or to one another by means of hairlike appendages, each called a _

A

fimbria

72
Q

Acquiring an R plasmid would allow a bacterium to do what?

A

Resist antibiotics

73
Q

Which of the following is not a true statement concerning bacterial flagella?

A

Bacterial flagella are homologous to the flagella of eukaryotic cells.

74
Q

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?

A

Exaptation

75
Q

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

A

Prokaryotic cells living in the food will shrink from their cell walls, impacting their ability to reproduce.

76
Q

Which subgroup of proteobacteria contains many species that are predators of other bacteria?

A

Delta

77
Q

Which of the following is a disease caused by bacteria?

A

Tuberculosis

78
Q

Prokaryotes found inhabiting the Great Salt Lake would be

A

extreme halophiles

79
Q

Which of the following does not contribute to bacteria’s ability to evolve rapidly?

A

Sexual reproduction

80
Q

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

A

Carbon dioxide, nitrogen, water, light, and some minerals

81
Q

What are biofilms?

A

Biofilms are cooperative colonies of bacteria.

BIO 160 (4 decks)

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