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					Chapter 27: Bacteria and Archaea

Overview

1. The chapter opens with amazing tales of life at the extreme edge.
What are the “masters of adaptation”? Prokaryotes Describe the one
case you thought most dramatic.
Halobacterium survive in a salty environment in Owens Lake. They derive
      their
energy from the sun.
•Prokaryotes thrive almost everywhere, including places too acidic,
salty, cold, or hot for most other organisms
•Most prokaryotes are microscopic, but what they lack in size they
make up for in numbers
•There are more in a handful of fertile soil than the number of people
who have ever lived
•They have an astonishing genetic diversity

Concept 27.1 Structural and functional adaptations contribute to
prokaryotic success

2. Which two domains include prokaryotes?
•Prokaryotes are divided into two domains: bacteria and archaea
3. Let’s focus on some general details about prokaryotes.



a. Are they multicellular or unicellular?
•Most prokaryotes are unicellular, although some species form colonies


b. Compare their size relative to eukaryotic cells.
•Most prokaryotic cells are 0.5–5 µm, much smaller than the 10–100 µm
of many eukaryotic cell


c. What three shapes are most common? Label them on the figure.•The
three most common shapes are spheres (cocci), rods (bacilli), and spirals
d. What is the composition of the typical bacterial cell wall?
•Bacterial cell walls contain peptidoglycan, a network of sugar polymers
cross-linked by polypeptide


4. A key feature of prokaryotic cells is the cell wall.
What three functions does it provide for the cell?
•An important feature of nearly all prokaryotic cells is their cell wall,
which maintains cell shape, provides physical protection, and prevents
the cell from bursting in a hypotonic environment

5. Quick review! What material comprises the cell wall of plants?
Cellulose
Of fungi? Chitin

6. The cell walls of Archaeans are different. They lack peptidoglycan
 but contain polysaccharides and proteins.

7. Explain the difference between Gram-positive and Gram-negative
bacteria.
•Using the Gram stain, scientists classify many bacterial species into
Gram-positive bacteria have a thick cell wall made of peptidoglycan that
traps the crystal violet in the cytoplasm. The alcohol rinse does not
remove the crystal violet, which masks the added red safranin dye.
Gram-negative bacteria have a thinner layer of peptidoglycan, and it is
located in a layer between the plasma membrane and an outer
membrane. The crystal violet is easily rinsed from the cytoplasm, and
the cell appears pink or red. •Gram-negative bacteria with less
peptidoglycan, also have an outer membrane that can be toxic, and they
are more likely to be antibiotic resistant. •Many antibiotics target
peptidoglycan and damage bacterial cell walls.
8. What is a bacterial capsule?
•A polysaccharide or protein layer called a capsule covers many
prokaryotes
What functions may it serve?
•Some prokaryotes have fimbriae (also called attachment pili), which
allow them to stick to their substrate or other individuals in a colony
•Sex pili are longer than fimbriae and allow prokaryotes to exchange
DNA

9. Many prokaryotes are capable of directional movement. What is this
called? Motility

10. What bacterial feature makes this possible? Flagella
•Most motile bacteria propel themselves by flagella that are structurally
and functionally different from eukaryotic flagella
•In a heterogeneous environment, many bacteria exhibit taxis, the
ability to move toward or away from certain stimuli

11. Under ideal conditions, how quickly can E. coli divide?
•Prokaryotes reproduce quickly by binary fission and can divide every 1–
3 hours
What conditions check prokaryotic reproduction?
•Many prokaryotes form metabolically inactive endospores, which can
remain viable in harsh conditions for centuries

12. What three key features allow prokaryotic populations to consist of
      trillions of individuals?
•Three factors contribute to this genetic diversity:
–Rapid reproduction
–Mutation
–Genetic recombination

13. Compare prokaryotes to eukaryotes in terms of the following
      characteristics:

             Prokaryotes                            Eukaryotes
Size         0.5–5 µm                               10–100 µm
Genome       •The prokaryotic genome has less       •The eukaryotic
             DNA than the eukaryotic genome         genome has more
          •Most of the genome consists of a       DNA than the
          circular chromosome                     prokaryotic genome
Membranes •Bacterial cell walls contain           •Eukaryote cell walls
          peptidoglycan, a network of sugar       are made of cellulose
          polymers cross-linked by                (plants)or chitin
          polypeptides                            (fungi)

Location    •The typical prokaryotic genome is    Nucleus
of genome   a ring of DNA that is not
            surrounded by a membrane and that
            is located in a nucleoid region

Plasmids    •Some species of bacteria have        No plasmids
            smaller rings of DNA called
            plasmids

Ribosomes   Yes                                   Yes

14. What are the small circular, self-replicating pieces of DNA found in
      bacteria called?
Plasmids

15. Label the structures of a typical prokaryotes to eukaryotes in
      terms of the following characteristics:
Capsule: (1) A sticky layer that surrounds the cell wall of some
prokaryotes, protecting the cell surface and sometimes helping to glue
the cell to surfaces. (2) The sporangium of a bryophyte (moss,
liverwort, or hornwort).                    •A polysaccharide or protein
layer called a capsule covers many prokaryotes

Cell wall: A protective layer external to the plasma membrane in the
cells of plants, prokaryotes, fungi, and some protists. Polysaccharides
such as cellulose (in plants and some protists), chitin (in fungi), and
peptidoglycan (in bacteria) are an important structural component of cell
walls.

Fimbria: (plural, fimbriae) A short, hairlike appendage of a prokaryotic
cell that helps it adhere to the substrate or to other cells; also known
as an attachment pilus. Fimbriae’s attachment pili allow them to stick to
their substrate or other individuals in a colony
Flagellum:(fluh-jel´-um) (plural, flagella) A long cellular appendage
specialized for locomotion. Like motile cilia, eukaryotic flagella have a
core with nine outer doublet microtubules and two inner single
microtubules ensheathed in an extension of the plasma membrane.
Prokaryotic flagella have a different structure.

Nucleoid: (nu'-kle-oyd) A dense region of DNA in a prokaryotic cell.

Plasmid: (plaz´-mid) A small, circular, double-stranded DNA molecule
that carries accessory genes separate from those of a bacterial
chromosome. Plasmids are also found in some eukaryotes, such as
yeasts.

Ribosome: (ri'-buh-som') A complex of rRNA and protein molecules that
functions as a site of protein synthesis in the cytoplasm; consists of a
large and a small subunit. In eukaryotic cells, each subunit is assembled
in the nucleolus. See also nucleolus.

Sex pilus: (plural, sex pili) (pi'-lus, pi'-li) In bacteria, a structure that
links one cell to another at the start of conjugation; also known as a
conjugation pilus. •Sex pili are longer than fimbriae and allow
prokaryotes to exchange DNA

16. When conditions for survival are difficult, some species produce
endospores. What are these? Endospores (remain viable in harsh
conditions for centuries): Thick-coated, resistant cells produced by a
bacterial cell exposed to harsh conditions.

Can you name any species that form endospores?

Gram-positive, Aerobic or Facultative Endospore-forming Bacteria

In 1872, Ferdinand Cohn, a contemporary of Robert Koch, recognized
and named the bacterium Bacillus subtilis. The organism is Gram-
positive, capable of growth in the presence of oxygen, and forms a
unique type of resting cell called an endospore. The organism
represented what was to become a large and diverse genus of bacteria
named Bacillus, in the Family Bacillaceae.
Koch relied on Cohn's observations in his classic work (1876), The
etiology of anthrax based on the life history of Bacillus anthracis, which
provided the first proof that a specific microorganism could cause a
specific disease.
Robert Koch's original photomicrographs of Bacillus anthracis. In 1876,
Koch established by careful microscopy that the bacterium was always
present in the blood of animals that died of anthrax. He took a small
amount of blood from such an animal and injected it into a healthy
mouse, which subsequently became diseased and died. He was able to
recover the original anthrax organism from the dead mouse,
demonstrating for the first time that a specific bacterium is the cause
of a specific disease.

The genus Bacillus remained intact until 2004, when it was split into
several families and genera of endospore-forming bacteria, justifiable on
the basis of ssRNA analysis. In order to accommodate former members
of the genus Bacillus covered here, its title has been changed to "Gram-
positive aerobic or facultative endospore-forming bacteria".

Bacillus subtilis is one of the most understood prokaryotes, in terms of
molecular biology and cell biology. Its superb genetic amenability and
relatively large size have provided the powerful tools required to
investigate a bacterium from all possible aspects. Recent improvements
in fluorescence microscopy techniques have provided novel and amazing
insight into the dynamic structure of a single cell organism. Research on
Bacillus subtilis has been at the forefront of bacterial molecular biology
and   cytology,   and   the   organism   is   a   model   for   differentiation,
gene/protein regulation, and cell cycle events in bacteria.[3]

Concept 27.2: Rapid reproduction, mutation, and genetic recombination
promote genetic diversity in prokaryotes

17. You should now have some idea why there is so much potential for
      genetic diversity with bacterial populations. Although mutation is
      the major source of genetic variation in prokaryotes, listed below
      are the other three ways variation is introduced. Explain each
      one.
Source of          Summary Explaination
Variation
Transformation     •A prokaryotic cell can take up and incorporate
                   foreign DNA from the surrounding environment in a
                   process called transformation
Transduction       •Transduction is the movement of genes between
                   bacteria by bacteriophages (viruses that infect
                   bacteria)
Recombination      •Additional diversity arises from genetic
(Genetic           recombination
Recombination)     •Prokaryotic DNA from different individuals can be
                   brought together by transformation, transduction,
                   and conjugation

                   recombinant chromosome: A chromosome created
                   when crossing over combines the DNA from two
                   parents into a single chromosome.

                   recombinant DNA: A DNA molecule made in vitro
                   with segments from different sources.



18. Define transformation.
•A prokaryotic cell can take up and incorporate foreign DNA from the
surrounding environment in a process called transformation
                       This idea was first described by Frederick
Griffith (Concept 16.1):
•The discovery of the genetic role of DNA began with research by
Frederick Griffith in 1928
•Griffith worked with two strains of a bacterium, one pathogenic and
one harmless
•When he mixed heat-killed remains of the pathogenic strain with living
cells of the harmless strain, some living cells became pathogenic
•He called this phenomenon transformation, now defined as a change in
genotype and phenotype due to assimilation of foreign DNA
•In 1944, Oswald Avery, Maclyn McCarty, and Colin MacLeod announced
that the transforming substance was DNA
•Their conclusion was based on experimental evidence that only DNA
worked in transforming harmless bacteria into pathogenic bacteria
19. What is transduction?
•Transduction is the movement of genes          between   bacteria   by
bacteriophages (viruses that infect bacteria)
What is the vector for this process?
Bacteriophages

  1. Phage infects a bacterial cell that has alleles A+ and B+
  2. Host DNA (brown, in the illustration below) is fragmented, and
     phage DNA and proteins are inside. This is a donor cell.
  3. A bacterial DNA fragment (with the A+ allele) may be packaged in
     a phage capsule.
  4. Phage with the A+ allele from the donor cell infects a recipient
     A-B- cell, and recombination between donor DNA (brown) and
     recipient DNA (green) occurs at two places (dotted lines).
  5. The genotype of the resulting combinations (A+B-) differs from
     the s of both the donor (A+B+) and the recipient (A-B-).
20. Compare and contrast transduction and transformation?
 Transduction: Phages occasionally carry pieces of the host chromosomes
 containing bacterial genes from one cell (the donor) to another (the
 recipient). Recombination may cause the transferred DNA to be
 incorporated into the genome of the recipient. Transduction and
 transformation are alike in that they both carry DNA. They are
 different in that transduction is enabled by a vector to accomplish the
 process.
21. What is a sex pilus?
Sex pilus: (plural, sex pili) (pi'-lus, pi'-li) In bacteria, a structure that
links one cell to another at the start of conjugation; also known as a
conjugation pilus.

What is the F factor?
F factor: 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.

How are the two related?

Both are important in conjugation (DNA transfer)
•Conjugation is the process where genetic material is transferred
between bacterial cells

•Sex pili allow cells to connect and pull together for DNA transfer
•The DNA piece known as the F factor is required for the production of
sex pili

•The F factor can exist as a separate plasmid or as DNA within the
bacterial chromosome
•Cells without the F factor function as DNA recipients during
conjugation

•The F factor is transferable during conjugation

22. The F factor is an episome. This is a piece of DNA that can be
integrated within the main chromosome of the bacterium, or able to
exist as an independent plasmid.

What is the bacterial cell called?
F Factor

The F Factor as a Plasmid
•Cells containing the F plasmid function as DNA donors during
conjugation
•Cells without the F factor function as DNA recipients during
conjugation
The F factor is transferable during conjugation

The F Factor in the Chromosome
•A cell with the F factor built into its chromosomes functions as a donor
during conjugation
•The recipient becomes a recombinant bacterium, with DNA from two
different cells
•It is assumed that horizontal gene transfer is also important in
archaea

R Plasmids and Antibiotic Resistance
•R plasmids carry genes for antibiotic resistance
•Antibiotics select for bacteria with genes that are resistant to the
antibiotics
•Antibiotic resistant strains of bacteria are becoming more common

23. What occurs in bacterial conjugation?
•Conjugation is the process where genetic material is transferred
between bacterial cells
•Sex pili allow cells to connect and pull together for DNA transfer
•A piece of DNA called the F factor is required for the production of
sex pili
•The F factor can exist as a separate plasmid or as DNA within the
bacterial chromosome

24. When a mating bridge forms between a F+ cell and an F- cell and
the F plasmid is replicated and transformed, what is the status of the
F- cell afterward?
Recombinant F– bacterium

Conjugation and Transfer of an F plasmid, see figure below
   1. A cell carrying an F plasmid (an F+ cell) can form a mating bridge
      with an F- cell.
   2. A single strand of the F plasmid breaks at a specific point (tip of
      blue arrowhead) and begins to move into the recipient cell. A
      transfer continues, the donor plasmid rotates (red arrow). DNA
      replication begins.
   3. DNA replication continues in both donor and recipient cells, using
      the single parental strands of the F plasmid as templates to
      synthesize complementary strands (light blue).
   4. The plasmid in the recipient cell circularizes. Transfer and
      replication result in a complete F plasmid in each cell. Thus, both
      cells are now F+.

The F Factor as a Plasmid
•Cells containing the F plasmid function as DNA donors during
conjugation
•Cells without the F factor function as DNA recipients during
conjugation
•The F factor is transferable during conjugation




The F Factor in the Chromosome
•A cell with the F factor built into its chromosomes functions as a donor
during conjugation
•The recipient becomes a recombinant bacterium, with DNA from two
different cells
•It is assumed that horizontal gene transfer is also important in
archaea
25. What is an Hfr cell?
A cell with the F factor built into its chromosome is called an Hfr cell
(for high frequency of recombination). Like an F+ cell, an Hfr cell
functions as a donor during conjugation of an F- cell. (See figure
above.) When chromosomal DNA from an Hfr cell enters an F- cell,
homologous regions of the Hfr and the F- chromosomes may align,
allowing segments of their DNA to be exchanged. This results in the
production of a recombinant bacterium that has genes derived from two
different cells – a new genetic variant on which evolution can act.
Though these processes of horizontal gene transfer have so far been
studied almost exclusively in bacteria, it is assumed that they are
similarly important in archaea.

26. How are Hfr cells created?
Chromosomal genes can be transferred during conjugation when the
donor cell’s F factor is integrated into the chromosome. A cell with the
F factor built into its chromosome is called an Hfr cell (for high
frequency of recombination).

27. Summarize the transfer of genetic information from an Hfr cell to
       an F- cell.
Conjugation and transfer of part of an Hfr bacterial chromosome,
resulting in recombination, see figure above
    1. In an Hfr cell the F factor (dark blue) is integrated into the
        bacterial chromosome. Since an Hfr cell has all of the F factor
        genes, it can form a mating bridge with an F- cell and transfer
        DNA.
    2. A single strand of the F factor breaks and begins to move
        through the bridge. DNA replication occurs in both donor and
        recipient cells, resulting in double stranded DNA (daughter
        strands shown in lighter color).
    3. The mating bridge usually breaks before the entire chromosome
        is transferred. DNA recombination (indicated by dotted lines) can
        result in the exchange of homologous genes between the
        transferred fragment (brown) and the recipient cells chromosomes
        (green).
    4. The piece of DNA ending up outside of the bacterial chromosome,
        eventually, will be degraded by the cell’s enzymes. The recipient
      cell now contains a new combination of genes, but no F factor, it
      is a recombinant F- bacterium cell.

28. An understanding of R plasmids and antibiotic resistance will be
     important when you do a bacterial transformation lab. What are R
     plasmids?
R Plasmids and Antibiotic Resistance
•R plasmids carry genes for antibiotic resistance
•Antibiotics select for bacteria with genes that are resistant to the
antibiotics
•Antibiotic resistant strains of bacteria are becoming more common

Concept 27.3: Diverse nutritional and metabolic adaptations have evolved
in prokaryotes

29. Prokaryotes can be placed into four groups according to their mode
of nutrition, which is how they take in carbon and how they obtain
energy. List each group below, and summarize how each of them obtains
energy. Place a ** by the heterotrophs.

Mode of Nutrition    Energy        Carbon         Examples
                     Source        Source
Autotrophs           Obtain        CO2            Photsynthet-ic
•Photoautotroph      energy from                  prokayotes (e.g.
                     light                        cyanobacter-ia);
                                                  plants; certain protists
                                                  (e.g. algae)
Autotrophs           Obtain        CO2            Certain prokaryotes
•Chemeautotroph      energy from                  (e.g. Sulfulobus)
                     inorganic
                     chemicals

Hetertrophs**        Obtain        obtain         Certain prokaryotes
•Photoheterotro-     energy from   energy from    (e.g. Rhodobacteria,
ph                   light         organic        Chloroflexus
                                   chemicals

Hetertrophs**        obtain        obtain         Many prokaryotes
•Chemoheterotroph energy from      energy from    (e.g. Clostridium ) and
                  organic          organic        protists; fungi;
                  chemicals        chemicals      animals; and some
                                                  plants

30. Compare the metabolic requirements of each group with respect to
      oxygen.
The Role of Oxygen in Metabolism
Prokaryotic metabolism varies with respect to O2:
  Obligate Aerobes: Obligate aerobes require O2 for cellular respiration
  Obligate Anaerobes: are poisoned by O2 and use fermentation or
   anaerobic respiration
  Faculative Anaerobes: Facultative anaerobes can survive with or
   without O2

31. To which of the above groups do you think the bacterium
Clostridrium tetani, the causative agent of tetanus, belongs?
  Obligate Anaerobes: are poisoned by O2 and use fermentation or
   anaerobic respiration

32. Biofilms form dental plaque and result in tooth decay. They can
damage industrial and medical equipment and contaminate products.
          What are biofilms?
Biofilms are surface-coating colonies of one or more species of
prokaryotes that engage in metabolic cooperation.
                      How do individual cells cooperate to form dental
plaque?
Biofilms are surface-coating colonies

Concept 27.4: Molecular systematics is illuminating prokaryotic phylogeny

33. The work of Carl Roese changed our approach to the taxonomy of
      prokaryotes. How did it do this?
•Until the late 20th century, systematists based prokaryotic taxonomy
on phenotypic criteria
•Applying molecular systematics to the investigation of prokaryotic
phylogeny has produced dramatic results
34. As you read in the overview of this chapter, many archaea live on
the edge, and so are termed extremophiles. Where would you find these
types of archaea?
  Extreme halophiles:
  An organism that lives in a highly saline environment, such as the
   Great Salt Lake or the Dead Sea.
  Extreme thermophiles:
  An organism that thrives in hot environments (often 60–80°C or
   hotter) like volcanic springs 90°C .
The thermophiles are interesting because their DNA and enzymes are
stable at high temperatures. DNA polymerases from thermophiles are
important in polymerase chain reactions (see Chapter 20).
Amplifying DNA in Vitro: The Polymerase Chain Reaction (PCR)
•The polymerase chain reaction, PCR, can produce many copies of a
specific target segment of DNA
•A three-step cycle—heating, cooling, and replication—brings about a
chain reaction that produces an exponentially growing population of
identical DNA molecules
•The use of polymerase chain reaction (PCR) has allowed for more rapid
sequencing of prokaryote genomes

35. Pee yoo! Methanogens are found in many habitats.
What are some of these habitats?
•Methanogens live in swamps and marshes and produce methane as a
waste product
What do they all have in common?
•Methanogens are strict anaerobes and are poisoned by O2

36. Compare the three domains in life in this chart by filling in either
present or absent. One row is done for you.

A COMPARISON OF THE THREE DOMAINS OF LIFE
Characteristic                Bacteria Archaea                     Eukarya
Nuclear envelope              Absent   Absent                      Present
Membrane- enclosed organelles Absent   Absent                      Present
Introns                       Very     Present in some             Present
                              rare     genes
Histone proteins associated   Absent   Present in some             Present
with DNA                                     species
Circular chromosomes             Present     Present               Absent

Concept 27.5: Prokaryotes play crucial roles in the biosphere

37. Define each of these terms, and give a specific example of each of
     the roles
      that prokaryotes play in the terms marked with an asterisk, *.

  Decomposers*: Organisms 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
   detritivore.
  Sybiosis: An ecological relationship between organisms of two
   different species that live together in direct and intimate contact.
  Host: The larger participant in a symbiotic relationship, serving as
   home and food source for the smaller symbiont.
  Symbiont: (sim'-be-ont) The smaller participant in a symbiotic
   relationship, living in or on the host.
  Mutualism*: (myu´-chu-ul-izm) A symbiotic relationship in which both
   participants benefit.
  Commensalism*: (kuh-men´-suh-lizm) A symbiotic relationship in which
   one organism benefits but the other is neither helped nor harmed.
  Parasitism*: (par´-uh-sit-izm) A symbiotic relationship in which one
   organism, the parasite, benefits at the expense of another, the host,
   by living either within or on the host.
  Parasite: (par´-uh-sit) An organism that feeds on the cell contents,
   tissues, or body fluids of another species (the host) while in or on the
   host organism. Parasites harm but usually do not kill their host.
  Pathogens*: Organism or viruses that causes disease.

Concept 27.6: Prokaryotes have both harmful and beneficial impacts on
humans

•Some prokaryotes are human pathogens, but others have positive
interactions with humans

38. What are antibiotics?
Antibiotics are medicinal products that have an anti-bacterial effect -
they either kill bacteria in the system or keep them from reproducing,
allowing the infected body to heal by producing its own defenses and
overcome the infection. When antibiotics were isolated in the mid-
twentieth century, they were widely hailed as 'wonder drugs,' and
indeed, formerly life-threatening infections could now be easily cured
within a few days.
Why are they becoming less affective?
Bacterial strains have mutated extensively because of rapid reproduction
and natural selection.

39. There are many bacterial diseases. Make a list of six bad ones
here, and give as much information about each disease as you can find in
your text.

   1. Chlamydias:
      •These bacteria are parasites that live within animal cells
      •Chlamydia trachomatis (1) causes blindness and nongonococcal
      urethritis by sexual transmission
   2. Spirochetes:
      •These bacteria are helical heterotrophs •Some, such as
      Treponema pallidum (2), which causes syphilis, and Borrelia
      burgdorferi (3), which causes Lyme disease, are parasites
   3. Gram-Positive Bacteria:
      (4) Bacillus anthracis, the cause of anthrax
      (5) Clostridium botulinum, the cause of botulism
      (6) Some Staphylococcus and Streptococcus, which can be
      pathogenic

40. Explain how a normally harmless symbiont of our gut, E. coli, can
be the agent of serious food poisoning. (Tell the story of 0157:H7.)

•Symbiosis is an ecological relationship in which two species live in close
contact: a larger host and smaller symbiont
•Prokaryotes often form symbiotic relationships with larger organisms

In 2001 scientists sequenced the genome of 0157:H7 and compared
with the genome of E. coli, K-12.

  1. Phage infects a bacterial cell that has alleles A+ and B+
  2. Host DNA (brown, in the illustration below) is fragmented, and
     phage DNA and proteins are inside. This is a donor cell.
  3. A bacterial DNA fragment (with the A+ allele) may be packaged in
     a phage capsule.
  4. Phage with the A+ allele from the donor cell infects a recipient
     A-B- cell, and recombination between donor DNA (brown) and
     recipient DNA (green) occurs at two places (dotted lines).
  5. The genotype of the resulting combinations (A+B-) differs from
     the s of both the donor (A+B+) and the recipient (A-B-).
41. Not all bacterial activity is negative. Humans employ bacteria for
     many diverse activities. Cite three human applications of
     prokaryotes here.
      Prokaryotes in Research and Technology
      •Experiments using prokaryotes have led to important advances in
      DNA technology
      •Prokaryotes are the principal agents in bioremediation, the use of
      organisms to remove pollutants from the environment
        1. Recovery of metals from ores
        2. Synthesis of vitamins
        3. Production of antibiotics, hormones, and other products

Testing Your Knowledge: Self-Quiz Answers
Now you should be ready to test your knowledge. Place your answers
here:

1.________ 2.________ 3.________ 4._________

				
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