20–5 funguslike protists
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Biology
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20–5 Funguslike Protists
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20–5 Funguslike Protists
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What are the similarities and differences between funguslike protists and fungi?
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20–5 Funguslike Protists
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Funguslike protists are heterotrophs that absorb nutrients from dead or decaying organic matter.
Unlike most true fungi, funguslike protists contain centrioles. They also lack the chitin cell walls of true fungi.
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20–5 Funguslike Protists
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Slime Molds
What are the defining characteristics of the slime molds?
Slime Molds
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20–5 Funguslike Protists
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Slime Molds
Slime molds are funguslike protists that play key roles in recycling organic material.
At one stage of their life cycle, slime molds look just like amoebas.
At other stages, they form moldlike clumps that produce spores, almost like fungi.
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20–5 Funguslike Protists
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Slime Molds
Two groups of slime molds are recognized:
• Cellular slime molds, whose individual cells remain separated during every phase of the mold's life cycle.
• Acellular slime molds, which pass through a stage in which its cells fuse to form large cells with many nuclei.
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20–5 Funguslike Protists
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Slime Molds
Cellular Slime Molds
Most cellular slime molds live as free-living cells that are not easily distinguishable from soil amoebas.
In nutrient-rich soils, these amoeboid cells reproduce sexually and produce diploid zygotes.
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20–5 Funguslike Protists
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Slime Molds
Life Cycle of a Cellular Slime Mold
Fruiting body Spores Emerging
amoebas
Fruiting body
Aggregatedamoebas
Migrating colony
Solitary cell
Zygote
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Slime Molds
When food is scarce, the cells produce spores.
They emit chemicals to attract cells of the same species.
Cells gather into a colony that functions like one organism.
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Slime Molds
• The colony moves slightly, then stops to produce a fruiting body, a slender reproductive structure that produces spores.
• Then the spores are scattered from the fruiting body.
• Each spore produces one cell, starting the cycle again.
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20–5 Funguslike Protists
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Slime Molds
Acellular Slime Molds
Acellular slime molds begin as amoeba-like cells.
When they aggregate, their cells fuse to produce structures with many nuclei known as plasmodia.
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Slime Molds
Life Cycle of an Acellular Slime Mold
Spores Germinating
Maturesporangium Young
sporangium Matureplasmodium
Feedingplasmodium
Zygote
Fertilization
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Slime Molds
Fruiting bodies, or sporangia, arise from the plasmodium.
The sporangia produce haploid spores by meiosis.
Maturesporangium Young
sporangiumMature
plasmodium
Feedingplasmodium
Zygote
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20–5 Funguslike Protists
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Slime Molds
Spores scatter and germinate into flagellated cells.
Cells fuse to produce diploid zygotes.
Spores Germinating
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20–5 Funguslike Protists
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Water Molds
Water Molds
What are the defining characteristics of the water molds?
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20–5 Funguslike Protists
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Water Molds
Oomycetes, or water molds thrive on dead or decaying organic matter in water. Some water molds are plant parasites on land.
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Water Molds
Water molds produce thin filaments known as hyphae.
Water molds have cell walls made of cellulose and produce motile spores, two traits that fungi do not have.
Water molds reproduce both sexually and asexually.
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Water Molds
FERTILIZATION
MEIOSISSEXUAL
REPRODUCTION
ASEXUAL REPRODUCTION
Life Cycle of a Water Mold
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Water molds
Mycelium (2N)
FlagellatedSpores (N)
Zoosporangium
ASEXUAL REPRODUCTION
In asexual reproduction, portions of the hyphae develop into zoosporangia, which are spore cases.
Hypha
Germination and mitosis
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20–5 Funguslike Protists
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Water Molds
Mycelium (2N)
FlagellatedSpores (N)
Zoosporangium
Hypha
Germination and mitosis
ASEXUAL REPRODUCTION
Each produces flagellated spores that swim in search of food.
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20–5 Funguslike Protists
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Water Molds
Mycelium (2N)
FlagellatedSpores (N)
Zoosporangium
ASEXUAL REPRODUCTION
When they find food, the spores develop into hyphae, which then grow into new organisms.
Hypha
Germination and mitosis
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20–5 Funguslike Protists
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Water molds
Zoosporangium
Flagellated spores (N)Mycelium
(2N)
Oogonium Male nuclei (N)
Antheridium Egg cells (N)
Fertilization
Zygotes (2N)
SEXUAL REPRODUCTION
MEIOSIS
FERTILIZATION
Sexual reproduction occurs in specialized structures formed by the hyphae.
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20–5 Funguslike Protists
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Water molds
Flagellated spores (N)Mycelium
(2N)
Oogonium Male nuclei (N)
Antheridium Egg cells (N)
Fertilization
Zygotes (2N)
The antheridium produces male nuclei.
Zoosporangium
SEXUAL REPRODUCTION
MEIOSIS
FERTILIZATION
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20–5 Funguslike Protists
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Water molds
Flagellated spores (N)Mycelium
(2N)
Oogonium Male nuclei (N)
Antheridium Egg cells (N)
Fertilization
Zygotes (2N)
The oogonium produces female nuclei.
Zoosporangium
SEXUAL REPRODUCTION
MEIOSIS
FERTILIZATION
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20–5 Funguslike Protists
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Water molds
Flagellated spores (N)Mycelium
(2N)
Oogonium Male nuclei (N)
Antheridium Egg cells (N)
Fertilization
Zygotes (2N)
Fertilization occurs within the oogonium, and the spores that form develop into new organisms.
Zoosporangium
SEXUAL REPRODUCTION
MEIOSIS
FERTILIZATION
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Ecology of Funguslike Protists
Ecology of Funguslike Protists
Slime molds and water molds recycle organic material.
After organisms die, their tissues are broken down by slime molds, water molds, and other decomposers.
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20–5 Funguslike Protists
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Ecology of Funguslike Protists
Some funguslike protists can harm living things.
Land-dwelling water molds cause a number of plant diseases, including mildews and blights.
A water mold was responsible for the Great Potato Famine in the 1800s.
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20–5
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20–5
Unlike the true fungi, funguslike protists
a. do not have centrioles or cell walls made of chitin.
b. do not have centrioles but have cell walls made of chitin.
c. have centrioles but lack cell walls made of chitin.
d. have both centrioles and cell walls made of chitin.
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20–5
The spore cases formed by water molds are called
a. zoosporangia.
b. plasmodia.
c. antheridia.
d. sporophytes.
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20–5
The acellular slime molds got their name because
a. they are the only organisms that do not have cells.
b. they do not have true nuclei.
c. they have multinucleate hyphae.
d. their cells sometimes fuse to form structures with many nuclei.
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20–5
Organisms that spend part of their life cycle as independent, unicellular amoeba-like forms and then join together as a visible, sluglike colony are
a. cellular slime molds.
b. water molds.
c. acellular slime molds.
d. plasmodia.
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20–5
The Great Potato Famine was caused by a(an)
a. cellular slime mold.
b. acellular slime mold.
c. water mold.
d. plasmodia.
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