topic 19 simple organisms (prokaryotes) · photoautotroph, photoheterotroph (unique to ... describe...
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Topic 19 Simple Organisms (Prokaryotes)
CEB Textbook Chapter 15, pages 294-309
Mastering Biology, Chapter 15
› How did life first arise on Earth?
› To gain insight, scientists have
synthesized from scratch the entire genome of a small bacterium known as Mycoplasma mycoides and
transplanted the artificial genome into the cells of a closely related species called Mycoplasma capricolum.
© 2013 Pearson Education, Inc.
• The newly installed
genome
– took over the recipient cells,
– began cranking out
M. mycoides proteins, and
– reproduced to make more cells containing the synthetic M. mycoides genome.
Biology and Society: Has Life Been Created in the Lab?
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› Earth was formed about 4.6
billion years ago.
› Prokaryotes
evolved by about 3.5 billion
years ago,
began oxygen production
about 2.7 billion years ago,
lived alone for more than a
billion years, and
continue in great
abundance today.
© 2013 Pearson Education, Inc.
Figure 15.1a
Precambrian
Ancestor to all present-day life
Origin of Earth
Earth’s crust solidifies
Oldest prokaryotic fossils
Atmospheric oxygen begins to appear
Millions of years ago
4,500 4,000 3,500 3,000 2,500
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Figure 15.1b
Millions of years ago
2,000 1,500 1,000
Precambrian
Oldest eukaryotic fossils
Origin of multicellular organisms
Oldest animal fossils
Figure 15.1c
Millions of years ago
1,000 500 0
Precambrian Paleozoic Cenozoic Meso- zoic
Bacteria
Archaea
Plants
Fungi
Animals Cambrian explosion
Oldest animal fossils
Plants colonize land
Extinction of dinosaurs
First humans
Pro
tists
Pro
karyote
s Eu
karyote
s
Figure 15.UN03
Major episode Millions of years ago
All major animal phyla established
Plants and fungi colonize land
Origin of Earth
First multicellular organisms
Oldest eukaryotic fossils
Accumulation of O2 in atmosphere
Oldest prokaryotic fossils
500
530
1,200
1,800
2,400
3,500
4,600
Figure 15.2
Humans
Origin of solar system and Earth
1 4
2 3
0
What if we
use a clock
analogy to
tick down
all of the
major
events in
the history
of life on
Earth?
› All life today arises by the reproduction of preexisting life, or biogenesis.
› If this is true, how could the first organisms arise?
› From the time of the ancient Greeks until well into the 1800s, it was commonly believed that life regularly arises from nonliving matter, an idea called spontaneous generation.
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› Today, most
biologists think it
is possible that
life on early Earth
evolved from
simple cells
produced by
chemical and
physical
processes.
Resolving the Biogenesis Paradox
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› Observation: Modern biological macromolecules are all composed of elements that were present in abundance on early Earth.
› Question: Could biological molecules arise spontaneously under conditions like those on early Earth?
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› Hypothesis: A closed
system designed to
simulate early Earth
conditions could produce
biologically important
organic molecules from
inorganic ingredients.
› Prediction: Organic
molecules would form and
accumulate.
The Process of Science: Can Biological Monomers Form Spontaneously?
© 2013 Pearson Education, Inc.
Figure 15.4
Miller and Urey’s experiment
“Sea”
H2O
Sample for chemical analysis
Cooled water containing organic molecules
Cold water
Condenser
Electrode
“Atmosphere”
Water vapor
CH4
NH3 H2
› Results: After the apparatus had run for a week, an
abundance of organic molecules essential for life had
collected in the “sea,” including amino acids, the
monomers of proteins.
› These laboratory experiments
have been repeated and extended by other scientists
and
support the idea that organic molecules could have
arisen abiotically on early Earth.
The Process of Science: Can Biological Monomers Form Spontaneously?
© 2013 Pearson Education, Inc.
Figure 15.UN01
Bacteria
Archaea
Prokaryotes
Eukarya
Protists
Plants
Fungi
Animals
› Over millions of years
natural selection
favored the most
efficient pre-cells
and
the first prokaryotic
cells evolved.
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› Prokaryotes lived
and evolved all
alone on Earth for
about 2 billion
years.
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› Prokaryotes
are found wherever there is life,
have a collective biomass that is at least ten times that of all eukaryotes,
thrive in habitats too cold, too hot, too salty, too acidic, or too alkaline for any eukaryote,
cause about half of all human diseases, and
are more commonly benign or beneficial.
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› Compared to eukaryotes,
prokaryotes are
much more abundant
and
typically much smaller.
PROKARYOTES - They’re Everywhere!
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Colorized SEM
› Prokaryotic cells
lack a membrane-enclosed
nucleus,
lack other membrane-
enclosed organelles,
typically have cell walls
exterior to their plasma
membranes, but
display an enormous range
of diversity.
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Figure 4.4
Plasma membrane Cell wall
Capsule
Prokaryotic flagellum
Ribosomes
Nucleoid
Pili
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› The three most common shapes of prokaryotes
are
1. spherical (cocci),
2. rod-shaped (bacilli), and
3. spiral or curved.
Prokaryotic Forms
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Spherical (cocci) Rod-shaped (bacilli) Spiral or Curved
SHAPES OF PROKARYOTIC CELLS
› All prokaryotes are
unicellular.
› Some species
exist as groups of two
or more cells,
exhibit a simple
division of labor
among specialized cell
types, or
are very large,
dwarfing most
eukaryotic cells.
Prokaryotic Forms
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(a) Actinomycete
Cyanobacteria Giant Bacterium
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› About half of all prokaryotes are mobile, and many of
these travel using one or more flagella.
Prokaryotic Forms
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› In many natural environments, prokaryotes attach to surfaces in a highly organized colony called a biofilm, which
may consist of one or several species of prokaryotes,
may include protists and fungi,
can show a division of labor and defense against invaders, and
Prokaryotic Forms
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Biofilm can form on
almost any type of
surface, including
rocks,
metal,
plastic, and
organic material
including teeth.
Prokaryotic Forms
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› Most prokaryotes can
reproduce
by dividing in half by binary
fission and
at very high rates if conditions
are favorable.
› Some prokaryotes form
endospores, which are
thick-coated, protective cells
produced when the prokaryote
is exposed to unfavorable
conditions.
Prokaryotic Reproduction
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Endospore
Colorized TEM
› Biologists use the phrase “mode of nutrition” to
describe how organisms obtain energy and carbon.
Energy
Phototrophs obtain energy from light.
Chemotrophs obtain energy from environmental chemicals.
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Carbon
Autotrophs obtain carbon from carbon dioxide (CO2).
Heterotrophs obtain carbon from at least one organic
nutrient—the sugar glucose, for instance.
› We can group all organisms according to the four
major modes of nutrition if we combine the
energy source (phototroph versus chemotroph) and
carbon source (autotroph versus heterotroph).
Figure 15.12
MODES OF NUTRITION
Light Chemical Chemoautotrophs (Prokaryote Only)
Photoautotrophs
Photoheterotrophs (Prokaryote Only)
Chemoheterotrophs
Energy source
Elodea, an aquatic plant
Rhodopseudomonas Kingfisher with prey
Bacteria from a hot spring
Org
anic
co
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ou
nd
s
Car
bo
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ou
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› By comparing diverse
prokaryotes at the
molecular level,
biologists have identified
two major branches of
prokaryotic evolution:
1. Bacteria
2. Archaea (more closely
related to eukaryotes).
© 2013 Pearson Education, Inc. Ar
Plaque forming Bacteria
Archaea Cells
Bacteria
Archaea
Prokaryotes
Eukarya
Protists
Plants
Fungi
Animals
› Some archaea are “extremophiles.”
Halophiles thrive in salty environments.
Thermophiles inhabit very hot water.
Methanogens
inhabit the bottoms of lakes and swamps and
aid digestion in cattle and deer.
Archaea
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Salt-loving archaea (Halophiles) Heat-loving archaea (Thermophiles)
1) Pathogens
2) Chemical
Recycling/Decomposers
3) Bioremediation
4) Oxygen Revolution
› Bacteria and other organisms that cause disease
are called pathogens.
• Most pathogenic bacteria produce poisons.
Exotoxins are proteins bacterial cells
secrete into their environment.
Endotoxins are
not cell secretions but instead
chemical components of the outer
membrane of certain bacteria.
Figure 15.15
“Bull’s-eye” rash
Tick that carries the Lyme disease bacterium
Spirochete that causes Lyme disease
SEM
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› In October 2001,
endospores of the
bacterium that causes
anthrax were mailed to
members of the news
media and the U.S.
Senate.
› Five people died from this
attack.
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› Another bacterium
considered to have
dangerous potential as a
weapon is Clostridium
botulinum, producer of
the exotoxin botulinum,
which
blocks transmission of
nerve signals that
cause muscle
contraction and
is the deadliest poison
on Earth.
Biological Weapons
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› The bacterium enterobacteria Yersinia pestis that causes plague
is also a potential biological weapon,
is carried by rodents, and transmitted by fleas,
Infects lymph nodes and produces egg-size swellings called buboes under the skin, and
can be treated with antibiotics if diagnosed early.
Biological Weapons
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› Prokaryotes play
essential roles in
chemical cycles in
the environment and
the breakdown of
organic wastes and
dead organisms.
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› Bioremediation is the
use of organisms to
remove pollutants from
water,
air, and
soil.
› A familiar example is the
use of prokaryotic
decomposers in sewage
treatment.
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› Certain bacteria
can decompose petroleum and
are useful in cleaning up oil spills.
Figure 15.17
Liquid wastes Outflow
Rotating arm spraying liquid wastes
Rock bed coated with aerobic prokaryotes and fungi
Photosynthetic bacteria were most likely responsible for rise in levels of oxygen in the atmosphere 2500 mya which allowed the first respiring eukaryotes to develop
Two main domains – Bacteria and Archaea
Three common shapes – Spherical, Rod, Spiral
Four main modes of nutrition –
Photoautotroph, Photoheterotroph (unique to
prokaryotes), Chemoautotroph (unique to
prokaryotes), Chemoheterotroph
Bacterial impact on life on Earth – Pathogens,
Chemical Recycling, Bioremediation, Oxygen
Revolution
Topic 20 Microbes with Complex Cells
(Eukaryotes)
CEB Textbook Chapter 15 pages 306-311, & Chapter 16, pages 328-332
Mastering Biology, Chapters 15 and 16
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Learning outcomes: After studying this topic you should be able to:
•Explain the fundamental difference
between protists and fungi as compared to
bacteria and archaea.
•List the four main types of protists and briefly describe an example of each type.
•Describe the basic structure of fungi and
explain how they feed and reproduce.
•Describe examples of important impacts
that fungi have in medicine and agriculture.
Figure 15.UN02
Bacteria
Archaea
Prokaryotes
Eukarya
Protists
Plants
Fungi
Animals
› Protists are
eukaryotes that are not
fungi, animals, or plants,
mostly unicellular, and
ancestral to all other
eukaryotes.
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› Eukaryotic cells evolved by
the infolding of the plasma
membrane of a prokaryotic
cell to form the
endomembrane system
and
a process known as
endosymbiosis.
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› Endosymbiosis
refers to one species living inside another host species
and
is the process by which eukaryotes gained
mitochondria and chloroplasts.
Figure 15.19
(a) Origin of the endomembrane system (b) Origin of mitochondria and chloroplasts
Plasma membrane DNA
Cytoplasm
Endoplasmic reticulum
Nucleus
Nuclear envelope
Ancestral prokaryote
Membrane infolding
Cell with nucleus and endomembrane system
Photosynthetic eukaryotic cell
Photosynthetic prokaryote
Aerobic heterotrophic prokaryote
Endosymbiosis
Mitochondrion
Chloroplast
Figure 15.20
(a) An autotroph: Caulerpa, a multicellular alga
(b) A heterotroph: parasitic trypanosome
(c) A mixotroph: Euglena
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› Protist habitats are diverse and include
oceans, lakes, and ponds,
damp soil and leaf litter, and
the bodies of host organisms with which they share mutually beneficial relationships, such as unicellular algae and reef-
building coral animals, and
cellulose-digesting protists and termites.
The Diversity of Protists
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1)Protozoans
2)Slime Molds
3)Algae
4)Seaweed
› Protozoans are protists that live primarily by ingesting
food are called
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Figure 15.22
A foram
A flagellate: Giardia
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Another flagellate: Trichomonas An amoeba
Red blood cell
Apical complex
TEM
An apicomplexan A ciliate
Cilia
Cell “mouth”
Main Types of Protozoan
a) Flagellates - Protozoans with
flagella
› are typically free-living, but some are
nasty parasites.
Main types of Protozoans
b) Amoebas are characterized by
great flexibility in their body shape
and
the absence of permanent
organelles for locomotion.
› Most species move and feed by
means of pseudopodia (singular,
pseudopodium), temporary
extensions of the cell.
c) Forams – Are protozoans
which have shells.
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Main types of Protozoans
d) Apicomplexans are
named for a structure at their
apex (tip) that is specialized
for penetrating host cells and
tissues,
all parasitic, and
able to cause serious human
diseases, such as malaria
caused by Plasmodium.
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Figure 15.22e
Red blood cell
Apical complex
TEM
An apicomplexan
› Another apicomplexan is Toxoplasma,
occurring in the digestive tracts of millions of people in the United States but
held in check by the immune system.
› A woman newly infected with Toxoplasma during pregnancy can pass the parasite to her unborn child, who may suffer nervous system damage.
Main types of Protozoans
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e) Ciliates are protozoans that
are named for their use of
hair-like structures called
cilia to move and sweep
food into their mouths,
are mostly free-living
(nonparasitic), such as the
freshwater ciliate
Paramecium, and
include heterotrophs and
mixotrophs.
Main types of Protozoans
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Figure 15.22f
LM
A ciliate
Cilia
Cell “mouth”
› Slime molds
resemble fungi in
appearance and lifestyle
due to convergence, but
are more closely related to
amoebas.
› The two main groups of
these protists are
plasmodial slime molds
and
cellular slime molds.
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› Plasmodial slime
molds
are named for the
feeding stage in their
life cycle, an amoeboid
mass called a
plasmodium,
are decomposers on
forest floors, and
can be large.
Types of Slime Molds
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› Cellular slime molds have an
interesting and complex life
cycle of successive stages:
a feeding stage of solitary
amoeboid cells,
a swarming stage as a slug-
like colony that can move and
function as a single unit, and
a stage during which they
generate a stalk-like
multicellular reproductive
structure.
Types of Slime Molds
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Figure 15.24
Life stages of a cellular slime mold
Slug-like colony
Amoeboid cells
Reproductive structure
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1
2
3
› Algae are
photosynthetic protists
whose chloroplasts
support food chains in
freshwater and
marine ecosystems.
› Many unicellular algae
are components of
plankton, the
communities of mostly
microscopic organisms
that drift or swim weakly
in aquatic environments.
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• Unicellular algae include
– dinoflagellates, with
– two beating flagella and
– external plates made of
cellulose,
– diatoms, with glassy cell walls containing silica, and
– green algae.
3. Unicellular and Colonial Algae (Protists)
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• Green algae are
– unicellular in most freshwater lakes and
ponds,
– sometimes flagellated,
such as Chlamydomonas, and
– sometimes colonial, forming a hollow ball of flagellated cells as seen
in Volvox.
3. Unicellular and Colonial Algae (Protists)
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Figure 15.25
(a) A dinoflagellate, with its wall of protective plates
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(b) A sample of diverse diatoms, which have glassy walls
(c) Chlamydomonas, a unicellular green alga with a pair of flagella
(d) Volvox, a colonial green alga
› Seaweeds
are large, multicellular marine
algae,
grow on or near rocky
shores,
are only similar to plants
because of convergent
evolution,
are most closely related to
unicellular algae, and
are often edible.
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› Seaweeds are classified
into three different
groups, based partly on
the types of pigments
present in their
chloroplasts:
1. green algae,
2. red algae, and
3. brown algae (including
kelp).
Seaweeds
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Brown algae Red algae Green algae
› Multicellular organisms have specialized cells that are dependent on each other and
perform different functions, such as feeding,
waste disposal,
gas exchange, and
protection.
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› Colonial protists likely formed the
evolutionary links between
unicellular and
multicellular organisms.
› The colonial green alga Volvox
demonstrates one level of specialization
and cooperation.
http://www.youtube.com/watc
h?v=He9FSeGRi3A
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Figure 15.27-1
Unicellular protist
An ancestral colony may have formed when a cell divided and remained attached to its offspring.
Figure 15.27-2
Unicellular protist
Locomotor cells
Food- synthesizing cells
Cells in the colony may have become specialized and interdependent.
An ancestral colony may have formed when a cell divided and remained attached to its offspring.
Figure 15.27-3
Unicellular protist
Locomotor cells
Food- synthesizing cells Somatic
cells
Gamete
Additional specialization may have led to sex cells (gametes) and nonreproductive cells (somatic cells).
Cells in the colony may have become specialized and interdependent.
An ancestral colony may have formed when a cell divided and remained attached to its offspring.
Any Eukaryote that is not a fungi, animal or
plant!
Four main types
1) Protozoans (flagellates, amoebas,
apicomplexans, and ciliates) – aquatic and
ingest their food
2) Slime moulds –decomposers, resemble fungi
but not closely related
3) Algae – (dinoflagellates, diatoms, unicellular
green algae) – photosynthetic, support food
chains in fresh water and marine ecosystems
4) Seaweed – (green, red and brown algae) –
large multicellular marine algae
› Fungi are
eukaryotes,
typically multicellular, and
more closely related to animals
than plants, arising from a
common ancestor about 1.5
billion years ago.
FUNGI
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come in many shapes and sizes and
represent more than 100,000 species.
› Fungi have unique
structures and
forms of nutrition.
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Figure 16.22
Orange fungi
Mold
Predatory fungus
Budding yeast A “fairy ring”
Bud
Roundworm Body of fungus
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› The bodies of most fungi are
constructed of threadlike filaments
called hyphae.
› Hyphae are minute threads of
cytoplasm surrounded by
a plasma membrane and
cell walls mainly composed of
chitin (not cellulose like in plants!).
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› Hyphae branch repeatedly,
forming an interwoven network
called a mycelium (plural,
mycelia), the feeding structure of
the fungus.
› Fungi
are chemoheterotrophs
and
acquire their nutrients by
absorption.
› A fungus is a decomposer
digests food outside its
body by secreting
powerful digestive
enzymes to break down
the food and
absorbs the simpler food
compounds.
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Figure 16.23
Reproductive structure
Mycelium
Hyphae Spore-producing structures
› Mushrooms
arise from an
underground mycelium
and
mainly function in
reproduction.
› Fungi reproduce by
releasing haploid spores
that are produced either
sexually or
asexually.
Fungal Reproduction
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Animation: Fungal Reproduction and
Nutrition
Right click slide / select “Play”
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› Fungi and bacteria
are the principal decomposers of ecosystems and
keep ecosystems stocked with the inorganic nutrients
necessary for plant growth.
› Without decomposers, carbon, nitrogen, and other
elements would accumulate in nonliving organic
matter.
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› Fungi have
an enormous ecological impact and
many interactions with humans.
› Molds can destroy
fruit,
grains,
wood, and
human-made material.
Fungi as Decomposers
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› Parasitic fungi absorb nutrients from the cells or body fluids of living hosts.
› Can cause serious economic losses in agriculture
› Of the 100,000 known species of fungi, about 30% make their living as parasites, including
Dutch elm disease and
deadly ergot, which infests grain.
Potato blight
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(a) An American elm tree killed by
Dutch elm
disease fungus
Figure 16.24b
(b) Ergots
› About 50 species of fungi are
known to be parasitic in
humans and other animals,
causing
lung and vaginal yeast
infections such as thrush
athlete’s foot
facial eczema
Parasitic Fungi
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› Observation: In 1692, eight young
girls were accused of being witches
and had symptoms consistent with
ergot poisoning.
› Question: Did an ergot outbreak
cause the witch hunt?
› Hypothesis: The girls’ symptoms
were the result of ergot poisoning.
› Prediction: The historical facts would
be consistent with this hypothesis.
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› Results: Agricultural records
from 1691, before the symptoms appeared, indicated a particularly warm and wet year, in which ergot thrives.
Records from the following year, when accusations of witchcraft died down, indicate a dry year consistent with an ergot die-off.
This correlation is consistent with the hypothesis but not conclusive.
The Process of Science: Did a Fungus Lead to the Salem Witch Hunt?
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› Fungi are commercially
important. Humans eat them
and use them to
produce medicines such as
penicillin (the first ever
antibiotic!),
decompose wastes, and
produce bread (yeast),
beer, wine, and cheeses.
Mushrooms and Truffles
are grown for food
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Figure 16.26
Chicken of the woods
Giant puffball
Chanterelle mushrooms
Figure 16.27
Penicillium Zone of inhibited growth
Staphylococcus
› Mutually beneficial
symbiotic relationships
between plants and fungi
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› Examples include
Mycorrhizae, a fungi which
increases the surface area of plant
roots allowing them to absorb more
minerals and water from the soil,
and
Lichens, the association of fungi
and algae. Algae can create sugars
by photosynthesis which feeds
both. Fungi increases surface area
allowing more water absorption.
Figure 16.28
Algal cell
Lichens: symbiotic associations of fungi and algae
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Fungal hyphae
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Unicellular or multicellular eukaryotes
Chemoheterotrophs – Digest their food externally and absorb nutrients, more closely related to animals than
plants
Consist of threadlike hyphae, forming a mycelium
Reproduce by releasing spores
Ecological Impact of Fungi
Principal decomposers of ecosystems
Parasites of people and other animals and plants. Beneficial to some plants to increase root surface
area.
Important in manufacture of food (bread, beer, wine,
mushrooms, truffles) and antibiotics
Symbiotic Relationship with plants – Fungi live on roots
of plants (gets nutrients) and increase surface area of plant roots (plant can absorb more water/minerals
Homework Prokaryotes and Eukaryotes
1) Unit Assessment Topic 19 and 20
2) Mastering Biology Assignment Prokaryotes and Eukaryotes
3) Mastering Biology activities:
Prokaryotic Cell Structure and
Function, Classification of
Prokaryotes
4) Complete the tables in study notes for Topic 19 and 20
5) Fill in Key Terms tables for Topic 19
and 20
VIDEOS Crash course in Fungi
http://www.youtube.com/watch?v=m4DUZhnNo4s
Fungi Lesson
http://www.youtube.com/watch?v=dj9m7Oc36wM
Crash course Archaea, Bacteria (Prokaryotes) and Protists (Unicellular
Eukaryotes) http://www.youtube.com/watch?v=vAR47-g6tlA
Bacteria Lesson
http://www.youtube.com/watch?v=h-z9-9OOWC4