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Chapter 12 – : , Fungi & Helminths

1. Protists • 2. Fungi

3. Helminths

1. Protists

A. Algae

B. Protozoa

A. Algae

1 Overview of the Algae Characteristics of algae: • unicellular or multicellular eukaryotes • almost all are photoautotrophs (photosynthetic) • all are essentially aquatic (live in fresh or saltwater) • all are capable of asexual • some are capable of as Algal phyla we will consider: Phaeophytes () Rhodophytes () Chlorophytes () Water

**produce an estimated 80% of O2 in the atmosphere!**

Brown Algae (Phaeophyta) • macroscopic referred to as “” • largest members of the Protista

• can grow 20 cm/day • contain distinct vegetative structures • holdfast anchors kelp to surface • stemlike stipes • leaflike blades • provide buoyancy

Red Algae (Rhodophyta)

• macroscopic seaweeds that in deep water where only blue light penetrates

• source of “” (used in culture plates)

• source of “carageenan” ( in )

2 Green Algae ()

• most are microscopic (uni- & multicellular), some are macroscopic • believed to have given rise to the

Diatoms • unicellular or filamentous (form multicellular filaments)

• have a unique wall structure composed of a called pectin & silica • responsible for geometric, glass-like appearance • widely distributed throughout photic zone

• important part of aquatic webs

Dinoflagellates • what are commonly referred to as “

• unicellular algae with 2 perpendicular flagella

• some produce potent neurotoxins • source of toxic algal blooms (e.g., “red ”)

• important part of the oceanic

3 Water Molds (Oomycota) • have a “-like” appearance but are protists • cell walls made of (not ) • have flagella (fungal cells never have flagella)

• most water molds are

• play an important role in recycling

B. Protozoa

Overview of the Protozoa Characteristics of protozoa: • all are unicellular eukaryotes lacking a • all are (a few can be photosynthetic) • capable of (some sexual repr.) • parasitic have complex cycles • some form protective cysts (when are bad) Protozoan phyla we will consider: Archaeozoa Ciliophora Microspora

4 Archaezoa • do NOT have mitochondria • have an analogous called a • most have multiple flagella • several parasitic genera can cause human • Trichomonas, Giardia

Apicomplexa

• non-motile obligate intracellular parasites

• have a unique “apical complex” of fibers and that release digestive

• aid in penetration of

• includes species of responsible for the disease malaria

• e.g., P. vivax & P. falciparum

Plasmodium vivax Life Cycle (malaria)

5 Ciliophora (“”)

• all have many small projections called cilia • used for locomotion & to direct food into the • have contractile (“mouth”) to expel excess water taken in by osmosis • some have multiple nuclei (expelled by exocytosis)

Sexual Reproduction in Ciliates Most ciliates are capable of sexual reproduction by a process called conjugation:

• conjugating ea produce 4 haploid micronuclei by , 3 of which disintegrate

• remaining divides by (2)

• exchange of 1 micronucleus between cells

• “old” & “new” micronuclei fuse, divide by mitosis, one of which replaces conjugating Paramecia original micronucleus

Euglenozoa

• some are photosynthetic () • have a light-sensitive eyespot & a single • includes the hemoflagellates (Trypanosoma) • responsible for “sleeping sickness” & Chagas disease

6 Amoebozoa

• aka “” • have distinct form of locomotion called “

• extend cytoplasmic projections called pseudopods

• also used to engulf and ingest food by

Slime Molds

• have characteristics of both & fungi but but are not true fungi

• slime molds are split into 2 groups:

Cellular Slime Molds • form large aggregates under unfavorable conditions • are considered part of the Amoebozoa

Plasmodial Slime Molds • only exist in large multinuclear aggregates • are classified in their own phylum

Cellular Slime Life Cycle

in unfavorable conditions

7 2. Fungi

Overview of the Fungi General characteristics of fungi: • all are eukaryotic absorptive heterotrophs • unicellular () or multicellular (molds, club fungi) • capable of asexual & sexual reproduction • have cell walls that contain chitin • aerobes w/some being facultative anaerobes • vast majority are terrestrial (i.e., live on land) • all fungi develop from haploid spores (no embryos) • do NOT have flagella (spores are immotile) **study of fungi is known as **

Structure of Multicellular Fungi

The (“body”) of a fungus consists largely of filamentous chains of cells called hyphae: • vegetative (non-reproductive) or aerial (reproductive) • some have septa (septate), some don’t (coenocytic)

8 Hyphae form a

On a rich source of nutrients, many hyphae can be produced to form a continuous mass called a mycelium. • vegetative hyphae spread across food source & “absorb” • aerial hyphae grow vertically & produce spores in a number of different ways, depending on the fungus

Reproduction in Filamentous Fungi Can reproduce asexually by fragmentation: • hyphae fragments grow by mitosis

Produce spores asexually or sexually: Asexual production • occurs at the tip of aerial hyphae • derived from single parent fungus • produced by mitosis

Sexual spore production • involves a partner of opposite type, meiosis

Asexual Spores

2 types of asexual spores:

1) those not enclosed in a sac are conidiospores (aka conidia)

• produced at the end of an aerial called a conidiophore

9 2) sporangiospores are produced within an enclosed sac called a • forms at the end of hypha called a sporangiophore

Sexual Spores Sexual spores in fungi require 3 phases not seen in the production of asexual spores: 1) transfer of a haploid nucleus to a cell of the opposite :

2) fusion of the haploid nuclei to form a diploid nucleus: • haploid nuclei may reproduce by mitosis before fusing • this is the ONLY occasion when fungal cells are diploid

3) meiosis to produce haploid sexual spores

The 3 Fungal Phyla

Zygomycota • conjugation fungi (molds)

Basidiomycota • club fungi (, smuts, rusts, )

Ascomycota • sac fungi (yeasts, molds, , )

10 • molds with coenocytic hyphae (no septa) • saprophytic (feed on dead vegetation) • produce spores in sporangia

Zygomycote Sexual Reproduction • plasmogamy occurs via conjugation • results in which grows a sporangium

**all 3 phyla conjugate, not just “conjugating fungi”**

Basidiomycota • commonly called the “club fungi” due to the presence of microscopic, club-shaped basidia:

• reproductive structures that produce

• some are parasitic

• many have mutualistic symbioses with various species

11 Basidiomycote Life Cycle • sexual reproduction via conjugation produces a basidioma:

• tightly packed aerial hyphae that make up the “fruiting body” (e.g., )

• basidia form on the “gills” and produce spores by meiosis

Ascomycota • produce sexual in a sac-like • produce asexual conidia

• includes molds with septate hyphae, yeasts lichens

Ascomycote Sexual Reproduction • conjugation between opposite mating types results in the formation of an ascus followed by karyogamy & meiosis (sometimes followed by mitosis)

• resulting 4 or 8 ascospores released when ascus opens

12 Yeasts Spherical unicellular fungi. • reproduce asexually by budding • also reproduce sexually

• facultative anaerobes (used for , …)

• important in biological research • studying the • production of & cerevisiae other important things

Fission Yeasts Oval or rod-shaped unicellular fungi. • reproduce asexually by • also reproduce sexually

• facultative anaerobes

• biological research

• also very important for studying the cell cycle

Schizosaccharomyces pombe

Lichens Lichens are actually 2 different in a mutualistic :

or green algae living among the hyphae of an ascomycote (or basidiomycote)

• fungus gets free carbs! • algae or cyanobacteria protected from elements

• important pioneers • can grow on inorganic surfaces, begin succession

13 Structure Fungal hyphae form the following structures:

• protective cortex

• inner medulla where algae grow

• rhizines to attach to growth surface

3. Helminths

Overview of the Helminths Helminths are parasitic worms found in 2 animal phyla, the Platyhelminthes () and the (roundworms).

• multicellular eukaryotic heterotrophs

• have complex life cycles frequently involving multiple hosts

• contain distinct organ systems • some may be reduced or absent due to dependence on host (e.g., no digestive system, no locomotion)

14 Platyhelminthes (flatworms): • typically hermaphroditic (monoecious) • have a proctostome (single opening, no anus) • we will look at 2 classes:

Trematodes (flukes) & Cestodes (tapeworms)

Nematodes (roundworms): • typically dioecious (2 ) • have complete digestive system (mouth & anus) • we will look at 2 types: pinworms & hookworms

Trematodes (flukes)

( fluke)

Members of this of flatworms are all parasites associated w/particular host tissues (liver, blood, ) • can have multiple larval stages and intermediate hosts • hermaphroditic (monoecious) • attach to host tissue via oral and ventral suckers • absorb nutrients through outer cuticle

A Fluke Life Cycle (lung fluke)

15 Tapeworms (cestodes) • intestinal parasites • scolex (head) has hooks & suckers for attachment • no digestive system, absorb nutrients • repeating proglottids have male & female reproductive organs (monoecious) • mature proglottids detach & pass w/feces allowing transmission to other hosts

A Tapeworm Life Cycle

Pinworms • entire life cycle in human hosts

• live in

• females lay eggs on anus

Enterobius vermicularis

• a dioecious parasitic roundworm () • transmitted to new hosts via eggs

16 Hookworms • dioecious nematodes

• live, mate, lay eggs in small intestine

• eggs pass with feces, hatch in

• larvae enter new host through skin, pass to cutting plates in via blood, lymph mouth used for attaching to • coughed up, swallowed and removing to reach small intestine host tissue repeat life cycle

Key Terms for Chapter 12 • holdfast, stipes, blade, • mitosome, cytostome, pseudopods • thallus, hyphae, mycelium, septate, coenocytic • vegetative, conidia, sporangia • plasmogamy, karyogamy, saprophytic • basidia, ascus • monoecious, dioecious • scolex, proglottids Relevant Chapter Questions rvw: 1, 2, 5, 11-14 MC: 4, 8-10

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