Funguslike Protists By: Alice, Darwin, Tate, and Kiara Chapter 20: Section 5 Funguslike Protists By: Alice, Darwin, Tate, and Kiara

Overview of the Section Funguslike protists grow in damp, nutrient-rich environments and absorb food through their cell membranes, much like fungi. Their cellular structures more closely resembles that of protists, though. Like fungi, the funguslike protists are heterotrophs that absorb nutrients from dead or decaying organic matter. They have centrioles, though, and lack the chitin cell walls of true fungi.

Slime Molds They are found in places that are damp and rich in organic matter, ex: the floor of a forest, a compost pile, etc. Slime molds are funguslike protists that play key roles in recycling organic material. Their appearances vary. Two broad groups of slime molds are recognized: -Cellular slime molds -Acellular slime molds

Examples of Slime Molds The yellow substance is the slime mold. Red raspberry slime mold.

Cellular Slime Molds Belong to the phylum Acrasiomycota During much of their life cycle, they are unicellular organisms that look and behave like animallike protists. When they aggregate, or collect into an unorganized whole, they behave like multicellular organisms. They spend most of their lives as free-living cells, easily confused with soil amoebas.

Cellular Slime Molds: Reproduction Slime molds can reproduce sexually and asexually. The sexual method is much like meiosis. The asexual method is described below: When they begin to run out of food, cellular slime molds reproduce to make spores that can survive with the limited resources. They first send out chemical signals that attract others of their species. Thousands of cells aggregate into a large sluglike colony that begins to function like a single organism, within a few days. The colony migrates a little, then halts and produces a fruiting body, or a slender reproductive structure that produces spores. These spores will eventually scatter, and give rise to a single amoeba-like cell, that will start the cycle all over again.

Visual of the cellular slime mold’s reproductive methods

Acellular Slime Molds Belong to the phylum Myxomycota. Like cellular slime molds, they begin their life cycles as amoeba-like cells. When they aggregate, their cells fuse to produce structures with many nuclei, or plasmodia. A plasmodium can grow several meters long. The plasmodium is a multinucleate (containing several nuclei) contained in a single cell membrane.

Acellular Slime Molds: Reproduction Acellular slime molds reproduce sexually: Small fruiting bodies, or sporangia, spring up from the plasmodium. The sporangia produce haploid spores by meiosis. The spores scatter to the ground, where they germinate into amoeba-like or flagellated cells These cells fused in a sexual union to produce diploid zygotes, which repeat the cycle.

Visual of Asexual Slime Mold’s Reproduction

What are water molds? Have you ever seen white fuzz growing on top of a dead fish in the water? If you have, then you have witnessed water mold in action! Water molds are also known as oomycetes. They are members of the phylum Oomycota. Oomycetes thrive on dead or decaying organic matter in water and some are plant parasites on land. They are not true fungi, though, because they produce thin filaments called hyphae. These hyphae do not have walls between their cells, and are multinucleate as a result. Water molds’ cell walls are composed of cellulose and they produce motile spores. These are two traits that real fungi do not have.

Water Mold Visual

Water Molds: Sexual Reproduction Sexual reproduction in water mold takes place in specialized structures, created by the hyphae. The antheridium produces male nuclei. The oogonium produces female nuclei. Fertilization occurs within the oogonium. Spores are formed, as a result, and they develop into new organisms.

Water Molds: Asexual Reproduction In asexual reproduction, portions of the hyphae develop into spore cases, or zoosporangia. Each zoosporangium creates flagellated spores that swim away to look for food. When they find food, the spores develop into hyphae, which in turn grow into new organisms.

Visual of Water Molds’ Asexual Reproduction