Fungal Biology

Coenocytic

hyphae without septa

Best approximation of one (1) fungal cell

a single hyphal compartment

Fungal analogue for membrane fluidity

ergosterol

Fungal Nuclear DNA Amount Relative to Other Eukaryotes

much lower

Fungal Repetitive DNA Amount Relative to Other Eukaryotes

much lower

Additional Function of Fungal Simple Sugars

dessication tolerance

How Trehalose Staves Off Dessication

it is very hydroscopic which causes a large amount of free water to bind to it that can be released if needed

Chitin Microfibril Structure

layers of antiparallel N-acetylglucosamine monomers

Why Chitin is Strong

the antiparallel layers form hydrogen bonds between them and crystallize

Fungal Plasma Membrane Difference

ergosterol based

Fungal Cytoskeleton Differrence

lack centrioles and instead have microtubule organizing centers

Mostly Unique Fungal Cell Features

vacuole abundance, energy storage, cell wall

Why Fungi Have So Many Vacuoles

they perform many different functions, including storage and lysis

How Fungi Store Energy

in lipids, in carbohydrates as glycogen, and in small sugars like trehalose or sugar alcohols

Main Components of the Fungal Cell Wall

chitin, glucans, mannoproteins, melanin

What Chitin is Made of

N-acetylglucosamine monomers

Where is Chitin Made in a Fungal Cell

chitin synthase in the plasma membrane

Types of Glucans

alpha and beta

Which Glucan is Soluble

alpha

Which Glucan is insoluble

beta

Alpha Glucan Purpose

forms the matrix, cytoplasm analogue gel for diffusion

Beta Glucan Purpose

structural support by crosslinking chitin fibres

What a Mannoprotein is

a protein with mannose attached to it

Where Mannoproteins are made

the surface of the rough ER

Do all Fungi have Melanin

no

Why do Some Fungi have Melanin

for UV protection, usually in a resting state

Closed Mitosis

mitosis occurring entirely within the nuclear membrane

How Long it Takes a Filamentous Fungi to Undergo Mitosis

Four Minutes

How Basidiomycetes Maintain a Dikaryotic State During Mitosis

through the use of clamp connections

Is Hyphal Growth Polar or Nonpolar

Polar

Why is Hyphal Growth Polar

it occurs only at the tip

How Hyphae use Turgor Pressure to Grow

it physically pushes against the tip, stretching it in a direction

How is Turgor Pressure Created / Maintained

solutes in the cytoplasm draw in water

Why is Turgor Pressure Lower at the Tip

because as the wall expands there are less solutes to draw in water and as the wall expands there is more space for the waster to go

Spitzenkorper

the area at the tip of a hyphae where vesicles gather and fuse, donating themselves and their contents to the new wall

Chitin /Glucan Synthase Recycling

synthases are embedded in the wall at the tip but as it grows and thickens the synthases will be far enough back to be unneeded and are then endocytosed to the Golgi/ER

Initial Hyphae Growth Angle

90 degrees

Mature Hyphae Growth Angle

45 degrees

Apical Dominance

the main hypha grows faster than hyphal branches

Undifferentiated Mycelia

all hyphae are focused on food and exploration

Differentiated Mycelia

hyphae have distinct zones and roles

Extending Zone

hyphae are focused on exploring and taking territory

Productive Zone

hyphae are focused on nutrient uptake and increasing biomass

Fruiting Zone

hyphae are focused on sporulation as resources are exhausted

Aged Zone

hyphae are focused on recycling themselves post-sporulation hyphae are focused onand sending those resources forward

Stalling

a phase in mycelial growth where resources are exhausted or conditions are poor where a cessation of growth occurs until conditions are reversed

Hyphal Zones From Innermost to Outermost

aged, fruiting, productive, extending

Hyphal Anastomosis

hyphae fusing together if it is beneficial to do so, typically to share nutrients or genetic material

When is Vegetative Growth Not Viable

when environmental conditions become unfavorable, resources are depleted, or competition is too high

When Vegetative Growth isn’t Viable What are the Two Strategies Fungi Employ

relocation or hibernation

Method of Fungal Relocation

sporulation; the fruiting body will not survive but the DNA will

Method of Fungal Hibernation

resting spores; the spore and the DNA will survive in place

Multihyphal Structures

method of relocation or hibernation available to septate fungi

Mycelial Strands

reversible aggregation of parallel undifferentiated hyphae reaching in the same direction in search of resources to send back

Rhizomorphs

reversible structure heavily resembling plant roots with three distinct layers that bores quickly underground in search of resources to send back

Three Rhizomorph Layers from Inner to Outermost

medulla, cortex, rind

Medulla

inner layer of a rhizomorph for active nutrient transport

Cortex

middle layer of a rhizomorph for active nutrient storage

Rind

outer layer of a rhizomorph of dead melanated cells for protection and structure

Sclerotia

irreversible resting structure common in plant pathogens made of two layers

Sclerotia Inner Layer Function

stores nutrients as lipids or glycogen

Sclerotia Outer Layer Function

dead melanated cells for protection and structure

How Sclerotia Make More Fungi

they have to germinate into either a mycelium, conidia, or sporocarp once conditions are favorable

Fungal Cell Wall Outer Layer

mannoproteins

Fungal Cell Wall Middle Layer

beta-glucans

Fungal Cell Wall Inner Layer

chitin

Woronin Bodies

organelles that block pores of simple septa after hyphal damage

Discharge

release of spores from the parent mycelium

Dispersal

movement of spores in the environment

Two Types of Spores

dispersal, survival

Hilum

the point where a spore was attached

Hilar Appendix

where Bueller’s drop forms

Bueller’s Drop

bead of water formed on the base of a spore

Adaxial Blob

bead of water formed on the top of a spore