Download Green algae

Chapter 16
Microbial Life: Prokaryotes and
Protists
PowerPoint Lectures for
Campbell Biology: Concepts & Connections, Seventh Edition
Reece, Taylor, Simon, and Dickey
© 2012 Pearson Education, Inc.
Lecture by Edward J. Zalisko
Figure 16.0_2
Chapter 16: Big Ideas
Prokaryotes
Protists
PROKARYOTES
© 2012 Pearson Education, Inc.
16.1 Prokaryotes are diverse and widespread
 Prokaryotic cells are smaller than eukaryotic cells.
– Prokaryotes range from 1–5 µm in diameter.
– Eukaryotes range from 10–100 µm in diameter.
 The collective biomass of prokaryotes is at least 10
times that of all eukaryotes.
© 2012 Pearson Education, Inc.
Figure 16.1
16.1 Prokaryotes are diverse and widespread
 Prokaryotes live in habitats
– too cold,
– too hot,
– too salty,
– too acidic, and
– too alkaline for eukaryotes to survive.
 Some bacteria are pathogens, causing disease.
But most bacteria on our bodies are benign or
beneficial.
© 2012 Pearson Education, Inc.
16.1 Prokaryotes are diverse and widespread
 Several hundred species of bacteria live in and on
our bodies,
– decomposing dead skin cells,
– supplying essential vitamins, and
– guarding against pathogenic organisms.
 Prokaryotes in soil decompose dead organisms,
sustaining chemical cycles.
© 2012 Pearson Education, Inc.
16.2 External features contribute to the success of
prokaryotes
 Prokaryotic cells have three common cell shapes.
– Cocci are spherical prokaryotic cells. They sometimes
occur in chains that are called streptococci.
– Bacilli are rod-shaped prokaryotes. Bacilli may also be
threadlike, or filamentous.
– Spiral prokaryotes are like a corkscrew.
– Short and rigid prokaryotes are called spirilla.
– Longer, more flexible cells are called spirochetes.
© 2012 Pearson Education, Inc.
Figure 16.2A
Cocci
Bacilli
Spirochete
16.2 External features contribute to the success of
prokaryotes
 Nearly all prokaryotes have a cell wall. Cell walls
– provide physical protection and
– prevent the cell from bursting in a hypotonic
environment.
 When stained with Gram stain, cell walls of
bacteria are either
– Gram-positive, with cell walls containing a thick layer of
peptidoglycan, or
– Gram-negative, with less peptidoglycan, and both an
inner and outer cell membrane.
© 2012 Pearson Education, Inc.
Figure 16.2B
 Gram stains are performed
to determine which
antibiotics to prescribe.
 Gram-negative bacteria are
generally more threatening
because of toxic lipid
molecules that are on the
outer membrane.
16.2 External features contribute to the success of
prokaryotes
 The cell wall of many prokaryotes is covered by a
capsule, a sticky layer of polysaccharides or
protein.
 The capsule
– enables prokaryotes to adhere to their substrate or to
other individuals in a colony and
– shields pathogenic prokaryotes from attacks by a host’s
immune system.
© 2012 Pearson Education, Inc.
Figure 16.2C
Tonsil cell
Capsule
Bacterium
16.2 External features contribute to the success of
prokaryotes
 Some prokaryotes have external structures that
extend beyond the cell wall.
– Flagella help prokaryotes move in their environment.
– Hairlike projections called fimbriae enable prokaryotes
to stick to their substrate or each other.
© 2012 Pearson Education, Inc.
Figure 16.2D
Flagella
Fimbriae
16.3 Populations of prokaryotes can adapt rapidly
to changes in the environment
 Prokaryote population growth
– occurs by binary fission,
– can rapidly produce a new generation within hours, and
– can generate a great deal of genetic variation
– by spontaneous mutations,
– increasing the likelihood that some members of the population
will survive changes in the environment.
© 2012 Pearson Education, Inc.
16.3 Populations of prokaryotes can adapt rapidly
to changes in the environment
 The genome of a prokaryote typically
– has about one-thousandth as much DNA as a
eukaryotic genome and
– is one long, circular chromosome packed into a distinct
region of the cell.
 Many prokaryotes also have additional small,
circular DNA molecules called plasmids, which
replicate independently of the chromosome.
© 2012 Pearson Education, Inc.
Figure 16.3A
Chromosome
Plasmids
16.3 Populations of prokaryotes can adapt rapidly
to changes in the environment
 Some prokaryotes form specialized cells called
endospores that remain dormant through harsh
conditions.
 Endospores can survive extreme heat or cold.
© 2012 Pearson Education, Inc.
Figure 16.3B
Endospore
16.4 Prokaryotes have unparalleled nutritional
diversity
 Prokaryotes exhibit much more nutritional diversity
than eukaryotes.
 Two sources of energy are used.
– Phototrophs capture energy from sunlight.
– Chemotrophs harness the energy stored in chemicals.
© 2012 Pearson Education, Inc.
16.4 Prokaryotes have unparalleled nutritional
diversity
 Two sources of carbon are used by prokaryotes.
– Autotrophs obtain carbon atoms from carbon dioxide.
– Heterotrophs obtain their carbon atoms from the
organic compounds present in other organisms.
© 2012 Pearson Education, Inc.
16.4 Prokaryotes have unparalleled nutritional
diversity
 The terms that describe how prokaryotes obtain
energy and carbon are combined to describe their
modes of nutrition.
– Photoautotrophs obtain energy from sunlight and use
carbon dioxide for carbon—cyanobacteria.
– Photoheterotrophs obtain energy from sunlight but get
their carbon atoms from organic molecules.
– Chemoautotrophs harvest energy from inorganic
chemicals and use carbon dioxide for carbon.
– Chemoheterotrophs acquire energy and carbon from
organic molecules. This is the largest group of
prokaryotes.
© 2012 Pearson Education, Inc.
Figure 16.4
Sunlight
Photoautotrophs
Chemicals
Chemoautotrophs
Oscilliatoria
Unidentified “rock-eating” bacteria
Photoheterotrophs
Chemoheterotrophs
Rhodopseudomonas
A Bdellovibrio attacking a
larger cell
CO2
Organic compounds
CARBON SOURCE
ENERGY SOURCE
16.5 CONNECTION: Biofilms are complex
associations of microbes
 Biofilms
– are complex associations of one or several species of
prokaryotes and
– may also include protists and fungi.
 Prokaryotes attach to surfaces and form biofilm
communities that
– are difficult to eradicate and
– may cause medical and environmental problems.
– May form on implanted medical devices such as
catheters
© 2012 Pearson Education, Inc.
16.5 CONNECTION: Biofilms are complex
associations of microbes
 Biofilms are large and complex “cities” of microbes
that
– communicate by chemical signals,
– coordinate a division of labor and defense against
invaders, and
– use channels to distribute nutrients and collect wastes.
© 2012 Pearson Education, Inc.
16.5 CONNECTION: Biofilms are complex
associations of microbes
 Biofilms that form in the environment can be
difficult to eradicate.
 Biofilms
– clog and corrode pipes,
– gum up filters and drains, and
– Coat the hulls of ships.
© 2012 Pearson Education, Inc.
Figure 16.5
16.6 CONNECTION: Prokaryotes help clean up
the environment
 Prokaryotes are useful for cleaning up contaminants
in the environment because prokaryotes
– have great nutritional diversity,
– are quickly adaptable, and
– can form biofilms.
© 2012 Pearson Education, Inc.
16.6 CONNECTION: Prokaryotes help clean up
the environment
 Bioremediation is the use of organisms to remove
pollutants from
– soil,
– air, or
– water.
© 2012 Pearson Education, Inc.
16.6 CONNECTION: Prokaryotes help clean up
the environment
 Prokaryotic decomposers are the mainstays of
sewage treatment facilities.
– Raw sewage is first passed through a series of screens
and shredders.
– Solid matter then settles out from the liquid waste,
forming sludge.
– Sludge is gradually added to a culture of anaerobic
prokaryotes, including bacteria and archaea.
– The microbes decompose the organic matter into material
that can be placed in a landfill or used as fertilizer.
© 2012 Pearson Education, Inc.
16.6 CONNECTION: Prokaryotes help clean up
the environment
 Liquid wastes are treated separately from the
sludge.
– Liquid wastes are sprayed onto a thick bed of rocks.
– Biofilms of aerobic bacteria and fungi growing on the
rocks remove much of the dissolved organic material.
– Fluid draining from the rocks is sterilized and then
released, usually into a river or ocean.
© 2012 Pearson Education, Inc.
Figure 16.6A
Rotating
spray arm
Rock bed coated
with aerobic
prokaryotes
and fungi
Liquid wastes
Outflow
16.6 CONNECTION: Prokaryotes help clean up
the environment
 Bioremediation is becoming an important tool for
cleaning up toxic chemicals released into the soil
and water by industrial processes.
 Environmental engineers change the natural
environment to accelerate the activity of naturally
occurring prokaryotes capable of metabolizing
pollutants.
© 2012 Pearson Education, Inc.
Figure 16.6B
16.7 Bacteria and archaea are the two main
branches of prokaryotic evolution
 New studies of representative genomes of
prokaryotes and eukaryotes strongly support the
three-domain view of life.
– Prokaryotes are now classified into two domains:
– Bacteria and
– Archaea.
– Archaea have at least as much in common with
eukaryotes as they do with bacteria.
© 2012 Pearson Education, Inc.
Table 16.7
16.8 Archaea thrive in extreme environments—
and in other habitats
 Archaeal inhabitants of extreme environments
have unusual proteins and other molecular
adaptations that enable them to metabolize and
reproduce effectively.
– Extreme halophiles thrive in very salty places.
– Extreme thermophiles thrive in
– very hot water, such as geysers, and
– acid pools.
© 2012 Pearson Education, Inc.
Figure 16.8A
16.8 Archaea thrive in extreme environments—
and in other habitats
 Methanogens
– live in anaerobic environments,
– give off methane as a waste product from
– the digestive tracts of cattle and deer and
– decomposing materials in landfills.
© 2012 Pearson Education, Inc.
Figure 16.8B
16.9 Bacteria include a diverse assemblage of
prokaryotes
 The domain Bacteria is currently divided into five
groups, based on comparisons of genetic
sequences.
 1. Proteobacteria
– are all gram negative,
– share a particular rRNA sequence, and
– represent all four modes of nutrition.
© 2012 Pearson Education, Inc.
16.9 Bacteria include a diverse assemblage of
prokaryotes
– Proteobacteria also include Rhizobium species that
– live symbiotically in root nodules of legumes and
– convert atmospheric nitrogen gas into a form usable
by their legume host.
– Symbiosis is a close association between
organisms of two or more species.
– Rhizobium is an endosymbiont, living within another
species.
© 2012 Pearson Education, Inc.
Figure 32.13B
Shoot
Bacteria within
vesicle in an
infected cell
Nodules
Roots
16.9 Bacteria include a diverse assemblage of
prokaryotes
 2. Gram-positive bacteria
– rival proteobacteria in diversity and
– include the actinomycetes common in soil.
– Streptomyces is often cultured by pharmaceutical
companies as a source of many antibiotics.
© 2012 Pearson Education, Inc.
Figure 16.9B
16.9 Bacteria include a diverse assemblage of
prokaryotes
 3. Cyanobacteria
– Cyanobacteria are the only group of prokaryotes with
plantlike, oxygen-generating photosynthesis.
– Some species, such as Anabaena, have specialized
cells that fix nitrogen.
© 2012 Pearson Education, Inc.
Figure 16.9C
Photosynthetic
cells
Nitrogen-fixing
cells
16.9 Bacteria include a diverse assemblage of
prokaryotes
 4. Chlamydias
– Chlamydias live inside eukaryotic host cells.
– Chlamydia trachomatis
– is a common cause of blindness in developing
countries and
– is the most common sexually transmitted disease in
the United States.
© 2012 Pearson Education, Inc.
Figure 16.9D
16.9 Bacteria include a diverse assemblage of
prokaryotes
 5. Spirochetes are
– helical bacteria and
– notorious pathogens, causing
– syphilis and
– Lyme disease.
© 2012 Pearson Education, Inc.
Figure 16.9E
16.10 CONNECTION: Some bacteria cause
disease
 All organisms are almost constantly exposed to
pathogenic bacteria.
 Most bacteria that cause illness do so by producing
a poison.
– Exotoxins are proteins that bacterial cells secrete into
their environment.
– Endotoxins are components of the outer membrane of
gram-negative bacteria.
© 2012 Pearson Education, Inc.
Figure 16.10
16.11 SCIENTIFIC DISCOVERY: Koch’s
postulates are used to prove that a
bacterium causes a disease
 Koch’s postulates are four essential conditions used
to establish that a certain bacterium is the cause of a
disease. They are
1. find the bacterium in every case of the disease,
2. isolate the bacterium from a person who has the disease
and grow it in pure culture,
3. show that the cultured bacterium causes the disease
when transferred to a healthy subject, and
4. isolate the bacterium from the experimentally infected
subject.
© 2012 Pearson Education, Inc.
16.11 SCIENTIFIC DISCOVERY: Koch’s
postulates are used to prove that a
bacterium causes a disease
 Koch’s postulates were used to demonstrate that
the bacterium Helicobacter pylori is the cause of
most peptic ulcers.
 The 2005 Nobel Prize in Medicine was awarded to
Barry Marshall and Robin Warren for this
discovery.
© 2012 Pearson Education, Inc.
Figure 16.11
16.12 CONNECTION: Bacteria can be used as
biological weapons
 Bacteria that cause anthrax and the plague can be
used as biological weapons.
– Bacillus anthracis killed five people in the United States
in 2001.
– Yersinia pestis bacteria
– are typically carried by rodents and transmitted by fleas,
causing the plague and
– can cause a pneumonic form of plague if inhaled.
© 2012 Pearson Education, Inc.
Figure 16.12
16.12 CONNECTION: Bacteria can be used as
biological weapons
 Clostridium botulinum produces the exotoxin
botulinum, the deadliest poison on earth.
 Botulinum toxin blocks transmission of nerve
signals and prevents muscle contraction.
© 2012 Pearson Education, Inc.
PROTISTS
© 2012 Pearson Education, Inc.
16.13 Protists are an extremely diverse assortment
of eukaryotes
 Protists
– are a diverse collection of mostly unicellular eukaryotes,
– may constitute multiple kingdoms within the Eukarya,
and
– refer to eukaryotes that are not
– plants,
– animals, or
– fungi.
© 2012 Pearson Education, Inc.
16.13 Protists are an extremely diverse assortment
of eukaryotes
 Protists obtain their nutrition in many ways. Protists
include
– autotrophs, called algae, producing their food by
photosynthesis,
– heterotrophs, called protozoans, eating bacteria and
other protists,
– heterotrophs, called parasites, deriving their nutrition
from a living host, and
– mixotrophs, using photosynthesis and heterotrophy.
© 2012 Pearson Education, Inc.
Figure 16.13A
Autotrophy
Caulerpa, a green alga
Heterotrophy
Giardia, a parasite
Mixotrophy
Euglena
16.13 Protists are an extremely diverse assortment
of eukaryotes
 Protists are found in many habitats including
– anywhere there is moisture and
– the bodies of host organisms.
© 2012 Pearson Education, Inc.
Figure 16.13B
16.13 Protists are an extremely diverse assortment
of eukaryotes
 Recent molecular and cellular studies indicate that
nutritional modes used to categorize protists do not
reflect natural clades.
 Protist phylogeny remains unclear.
 One hypothesis, used here, proposes five
monophyletic supergroups.
© 2012 Pearson Education, Inc.
16.14 EVOLUTION CONNECTION: Secondary
endosymbiosis is the key to much of protist
diversity
 The endosymbiont theory explains the origin of
mitochondria and chloroplasts.
– Eukaryotic cells evolved when prokaryotes established
residence within other, larger prokaryotes.
– This theory is supported by present-day mitochondria and
chloroplasts that
– have structural and molecular similarities to
prokaryotic cells and
– replicate and use their own DNA, separate from the
nuclear DNA of the cell.
© 2012 Pearson Education, Inc.
Figure 16.14_s1
Primary
endosymbiosis
Evolved into
Cyanobacterium chloroplast
2
Nucleus
Heterotrophic
eukaryote
1
Figure 16.14_s2
Primary
endosymbiosis
Green alga
Chloroplast
Evolved into
Cyanobacterium chloroplast
2
3
Nucleus
Heterotrophic
eukaryote
1
Autotrophic
eukaryotes
Chloroplast
Red alga
Figure 16.14_s3
Primary
endosymbiosis
Green alga
Chloroplast
Evolved into
Cyanobacterium chloroplast
2
3
Nucleus
Heterotrophic
eukaryote
1
Autotrophic
eukaryotes
Chloroplast
Red alga
4
Heterotrophic
eukaryotes
16.14 EVOLUTION CONNECTION: Secondary
endosymbiosis is the key to much of protist
diversity
 Secondary endosymbiosis is
– the process in which an autotrophic eukaryotic protist
became endosymbiotic in a heterotrophic eukaryotic
protist and
– key to protist diversity.
© 2012 Pearson Education, Inc.
Figure 16.14_s4
Primary
endosymbiosis
Secondary
endosymbiosis
Green alga
Chloroplast
Evolved into
Cyanobacterium chloroplast
2
3
Nucleus
Heterotrophic
eukaryote
1
Autotrophic
eukaryotes
Chloroplast
Red alga
4
Heterotrophic
eukaryotes
5
Figure 16.14_s5
Primary
endosymbiosis
Secondary
endosymbiosis
Green alga
Remnant of
green alga
Chloroplast
Evolved into
Cyanobacterium chloroplast
Euglena
2
3
Nucleus
Heterotrophic
eukaryote
1
Autotrophic
eukaryotes
Chloroplast
Red alga
4
Heterotrophic
eukaryotes
5
16.15 Chromalveolates represent the range of
protist diversity
 Chromalveolates include
– diatoms, unicellular algae with a glass cell wall
containing silica,
© 2012 Pearson Education, Inc.
Figure 16.15A
16.15 Chromalveolates represent the range of
protist diversity
 Chromalveolates include
– diatoms, unicellular algae with a glass cell wall
containing silica,
– dinoflagellates, unicellular autotrophs, heterotrophs,
and mixotrophs that are common components of marine
plankton and can cause red tides.
© 2012 Pearson Education, Inc.
Figure 16.15B
16.15 Chromalveolates represent the range of
protist diversity
 Chromalveolates include
– diatoms, unicellular algae with a glass cell wall
containing silica,
– dinoflagellates, unicellular autotrophs, heterotrophs,
and mixotrophs that are common components of marine
plankton and can cause red tides.
– brown algae, large, multicellular autotrophs,
© 2012 Pearson Education, Inc.
Figure 16.15C
16.15 Chromalveolates represent the range of
protist diversity
 Chromalveolates include
– diatoms, unicellular algae with a glass cell wall
containing silica,
– dinoflagellates, unicellular autotrophs, heterotrophs,
and mixotrophs that are common components of marine
plankton and can cause red tides.
– brown algae, large, multicellular autotrophs,
– water molds, unicellular heterotrophs,
© 2012 Pearson Education, Inc.
Figure 16.15D
16.15 Chromalveolates represent the range of
protist diversity
 Chromalveolates include
– diatoms, unicellular algae with a glass cell wall
containing silica,
– dinoflagellates, unicellular autotrophs, heterotrophs,
and mixotrophs that are common components of marine
plankton and can cause red tides.
– brown algae, large, multicellular autotrophs,
– water molds, unicellular heterotrophs,
– ciliates, unicellular heterotrophs and mixotrophs that
use cilia to move and feed,
© 2012 Pearson Education, Inc.
Figure 16.15E
Mouth
16.15 Chromalveolates represent the range of
protist diversity
 Chromalveolates include
– diatoms, unicellular algae with a glass cell wall
containing silica,
– dinoflagellates, unicellular autotrophs, heterotrophs,
and mixotrophs that are common components of marine
plankton and can cause red tides.
– brown algae, large, multicellular autotrophs (seaweed),
– water molds, unicellular heterotrophs (fungus-like),
– ciliates, unicellular heterotrophs and mixotrophs that use
cilia to move and feed, and
– a group including parasites, such as Plasmodium, which
causes malaria.
© 2012 Pearson Education, Inc.
16.16 CONNECTION: Can algae provide a
renewable source of energy?
 Fossil fuels
– are the organic remains of organisms that lived
hundreds of millions of years ago and
– primarily consist of
– diatoms and
– primitive plants.
© 2012 Pearson Education, Inc.
16.16 CONNECTION: Can algae provide a
renewable source of energy?
 Lipid droplets in diatoms and other algae may
serve as a renewable source of energy.
 If unicellular algae could be grown on a large scale,
this oil could be harvested and processed into
biodiesel.
 Numerous technical hurdles remain before
industrial-scale production of biofuel from algae
becomes a reality.
 http://www.youtube.com/watch?v=Qs0QZJ0rea0
© 2012 Pearson Education, Inc.
Figure 16.16
16.17 Rhizarians include a variety of amoebas
 The two largest groups of Rhizaria are among the
organisms referred to as amoebas.
 Amoebas move and feed by means of
pseudopodia, temporary extensions of the cell.
© 2012 Pearson Education, Inc.
16.17 Rhizarians include a variety of amoebas
 Foraminiferans
– are found in the oceans and in fresh water,
– have porous shells, called tests, composed of calcium
carbonate, and
– have pseudopodia that function in feeding and
locomotion.
© 2012 Pearson Education, Inc.
Figure 16.17A
16.17 Rhizarians include a variety of amoebas
 Radiolarians
– are mostly marine and
– produce a mineralized internal skeleton made of silica.
© 2012 Pearson Education, Inc.
Figure 16.17B
16.18 Some excavates have modified mitochondria
 Excavata has recently been proposed as a clade
on the basis of molecular and morphological
similarities.
 The name refers to an “excavated” feeding groove
possessed by some members of the group.
 Excavates
– have modified mitochondria that lack functional electron
transport chains and
– use anaerobic pathways such as glycolysis to extract
energy.
© 2012 Pearson Education, Inc.
16.18 Some excavates have modified mitochondria
 Excavates include
– heterotrophic termite endosymbionts
© 2012 Pearson Education, Inc.
Figure 16.13B
16.18 Some excavates have modified mitochondria
 Excavates include
– heterotrophic termite endosymbionts,
– autotrophic species,
– mixotrophs such as Euglena
© 2012 Pearson Education, Inc.
Figure 16.13A_3
Mixotrophy
Euglena
16.18 Some excavates have modified mitochondria
 Excavates include
– heterotrophic termite endosymbionts,
– autotrophic species,
– mixotrophs such as Euglena,
– the common waterborne parasite Giardia intestinalis,
© 2012 Pearson Education, Inc.
Figure 16.13A
Autotrophy
Caulerpa, a green alga
Heterotrophy
Giardia, a parasite
Mixotrophy
Euglena
16.18 Some excavates have modified mitochondria
 Excavates include
– heterotrophic termite endosymbionts,
– autotrophic species,
– mixotrophs such as Euglena,
– the common waterborne parasite Giardia intestinalis,
– the parasite Trichomonas vaginalis, which causes 5
million new infections each year of human reproductive
tracts,
© 2012 Pearson Education, Inc.
Figure 16.18A
Flagella
Undulating
membrane
16.18 Some excavates have modified mitochondria
 Excavates include
– heterotrophic termite endosymbionts,
– autotrophic species,
– mixotrophs such as Euglena,
– the common waterborne parasite Giardia intestinalis,
– the parasite Trichomonas vaginalis, which causes 5
million new infections each year of human reproductive
tracts, and
– the parasite Trypanosoma, which causes sleeping
sickness in humans.
© 2012 Pearson Education, Inc.
Figure 16.18B
16.19 Unikonts include protists that are closely
related to fungi and animals
 Unikonta is a controversial grouping joining
– amoebozoans and
– a group that includes animals and fungi, addressed at
the end of this unit on protists.
© 2012 Pearson Education, Inc.
16.19 Unikonts include protists that are closely
related to fungi and animals
 Amoebozoans have lobe-shaped pseudopodia and
include
– many species of free-living amoebas,
– some parasitic amoebas, and
– slime molds.
© 2012 Pearson Education, Inc.
Figure 16.19A
16.19 Unikonts include protists that are closely
related to fungi and animals
 Plasmodial slime molds
– are common where there is moist, decaying organic
matter and
– consist of a single, multinucleate mass of cytoplasm
undivided by plasma membranes, called a
plasmodium, not to be confused with Plasmodium,
the causative agent of malaria.
© 2012 Pearson Education, Inc.
Figure 16.19B
16.19 Unikonts include protists that are closely
related to fungi and animals
 Cellular slime molds
– are common on rotting logs and decaying organic
matter and
– usually exist as solitary amoeboid cells, but when food
is scarce, amoeboid cells
– swarm together, forming a slug-like aggregate that
wanders around for a short time and then
– forms a stock supporting an asexual reproductive
structure that produces spores.
© 2012 Pearson Education, Inc.
Figure 16.19C
16.20 Archaeplastids include red algae, green
algae, and land plants
 Archaeplastids include:
– red algae,
– green algae, and
– land plants.
© 2012 Pearson Education, Inc.
16.20 Archaeplastids include red algae, green
algae, and land plants
 Red algae
– are mostly multicellular,
– contribute to the structure of coral reefs, and
– are commercially valuable.
© 2012 Pearson Education, Inc.
Figure 16.20A
16.20 Archaeplastids include red algae, green
algae, and land plants
 Green algae may be unicellular, colonial, or
multicellular.
– Volvox is a colonial green algae, and
– Chlamydomonas is a unicellular alga propelled by two
flagella.
© 2012 Pearson Education, Inc.
Figure 16.20B
Volvox
Chlamydomonas
16.20 Archaeplastids include red algae, green
algae, and land plants
 Ulva, or sea lettuce, is
– a multicellular green alga with
– a complex life cycle that includes an alternation of
generations that consists of
– a multicellular diploid (2n) form, the sporophyte,
that alternates with
– a multicellular haploid (1n) form, the gametophyte.
© 2012 Pearson Education, Inc.
Figure 16.20C_s1
Mitosis
Male
gametophyte
Spores
Mitosis
Gametes
Female
gametophyte
Key
Haploid (n)
Diploid (2n)
Figure 16.20C_s2
Mitosis
Male
gametophyte
Spores
Mitosis
Gametes
Female
gametophyte
Fusion of
gametes
Zygote
Key
Haploid (n)
Diploid (2n)
Figure 16.20C_s3
Mitosis
Male
gametophyte
Spores
Mitosis
Meiosis
Gametes
Female
gametophyte
Fusion of
gametes
Sporophyte
Zygote
Mitosis
Key
Haploid (n)
Diploid (2n)
Figure 16.20C_2
16.21 EVOLUTION CONNECTION: Multicellularity
evolved several times in eukaryotes
 The origin of the eukaryotic cell led to an
evolutionary radiation of new forms of life.
 Unicellular protists are much more diverse in form
than simpler prokaryotes.
© 2012 Pearson Education, Inc.
16.21 EVOLUTION CONNECTION: Multicellularity
evolved several times in eukaryotes
 Multicellular organisms (seaweeds, plants,
animals, and most fungi) are fundamentally
different from unicellular organisms.
– A multicellular organism has various specialized cells
that perform different functions and are interdependent.
– All of life’s activities occur within a single cell in
unicellular organisms.
© 2012 Pearson Education, Inc.
Figure 16.21A
Green algae
Other green algae
Charophytes
Land plants
Amoebozoans
Unikonts
Ancestral eukaryote
Archaeplastids
Red algae
Nucleariids
Fungi
Choanoflagellates
Key
All unicellular
Both unicellular
and multicellular
All multicellular
Animals
You should now be able to
1. Describe the structures and functions of the diverse
features of prokaryotes; explain how these features have
contributed to their success.
2. Explain how populations of prokaryotes can adapt rapidly
to changes in their environment.
3. Describe the nutritional diversity of prokaryotes and explain
the significance of biofilms.
4. Explain how prokaryotes help clean up the environment.
5. Compare the characteristics of the three domains of life;
explain why biologists consider Archaea to be more closely
related to Eukarya than to Bacteria.
© 2012 Pearson Education, Inc.
You should now be able to
6.
Describe the diverse types of Archaea living in extreme
and moderate environments.
7.
Distinguish between the subgroups of the domain
Bacteria, noting the particular structure, special features,
and habitats of each group.
8.
Distinguish between bacterial exotoxins and endotoxins,
noting examples of each.
9.
Describe the steps of Koch’s postulates and explain why
they are used.
10. Explain how bacteria can be used as biological weapons.
© 2012 Pearson Education, Inc.
You should now be able to
11. Describe the extremely diverse assortment of eukaryotes.
12. Explain how primary endosymbiosis and secondary
endosymbiosis led to further cellular diversity.
13. Describe the major protist clades noting characteristics
and examples of each.
14. Describe the life cycle of Ulva, noting each form in the
alternation of generations and how each is produced.
15. Explain how multicellular life may have evolved in
eukaryotes.
© 2012 Pearson Education, Inc.
Figure 16.UN01
Nutritional mode
Energy source
Photoautotroph
Sunlight
Chemoautotroph
Inorganic chemicals
Photoheterotroph
Sunlight
Chemoheterotroph
Organic compounds
Carbon source
CO2
Organic compounds
Figure 16.UN02
Exotoxin
Secreted by cell
Endotoxin
Component of gramnegative plasma membrane
Staphylococcus aureus
Salmonella enteritidis