Module 3 – Lecture 1 11/03/14
Dr Robin Marushia (“Maru-sha”)/ Dr. M
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Tuesday 2:30 – 5PM
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Tree of Life: Fungi = Heterotrophic
Fungus = singular Fungi = plural
• Some of the primary decomposers of the earth
(along with heterotrophic bateria)
• Obtain carbon by breaking down organic
molecules synthesized by other organisms
Broken down in to two main groups (depends on how
carbon is obtained)
Saprotroph (Sapro = Death, Troph = to eat): From
nonliving material (decomposers)
Symbionts: Living organisms (either pathogens or
Symbiosis: close relationship between two organisms. Can be positive for both (mutualist) or negative
(pathogens) for one.
Decomposers: Breaking down nonliving organic material.
Pathogens or Parasites (+/-): “infect” living organisms. Take carbon sources directly from host, host is
negatively impacted by the interaction. May also act as decomposers once host is dead.
Mutualists (+/+ ): Take carbon sources directly from host, but engage in mutually beneficial interaction
by providing a service in return, usually providing water or nutrients from the soil.
Some fungi unicellular.
Most are multicellular: Primary made up of Hyphae (not roots but functions similar to roots)
• Most of the fungal organism is composed of the mycelium (makes up most of biomass of any
• hyphae (single cell strands): thread-like filaments of a fungus.
Fungi's grow via apical growth, unlike plants no meristems on the side, thus can only grow longer not
wider. Module 3 – Lecture 1 11/03/14
Apical growth: Hyphae grow outward by growth at tips
Absorptive nutrition: As fungi extend through their environment, they secrete enzymes into their
environment, breaking down large organic molecules around them into smaller components that can be
absorbed into the hyphae, hyphae then transports water / nutrients via cellular streaming (no pressure)
Fungi reproduce both asexually and sexually. Sexual propagules (unit that disperses to the env) are called
Hyphae / Mycelia Structure:
Fungi, like plants, have rigid cell walls. The walls are made of chitin (similar to insects which are primary
component of exoskeleton): a nitrogen-based polysaccharide.
Cross walls (septa) broken apart cell wall of some hyphae into cell-like compartments
Pores in the septa (or lack of septa) allow fluids in the cell to transport the water and nutrients via
cytoplasmic streaming & cellular gradiance.
Cytoplasmic streaming: allows nutrients to flow throughout hyphae.
Reproduction: (Haploid progeny,
either sexually or asexually
produced, are called spores).
Asexual reproduction: Hyphae cells
can split off and form haploid
spores, then disperses. Also, if
hyphae detaches it can form a new
Sexual reproduction: three steps!
• Plasmogamy: the fusion of
hyphae between two
individuals (not fusion of
• Karyogamy: the fusion of
two sexually compatible
hapoid nuclei following
plasmogamy (forming a
zygote (2n nucleus))
• Meiosis: the division of the diploid cell to haploid progeny following two sequential rounds of
nuclear and cellular division. The progeny are spores. Module 3 – Lecture 1 11/03/14
Fungal Phylogenetic Groups:
Fungi were present on Earth by at least 760 million years ago.
Once they appeared, fungi radiated into se