Introduction To Fungi

Question 1

Opistokonta

Answer 1

Large supergroup of eukaryotes including metazoans and fungi
-phagotrophic or osmotic (saprophytic, parasitic). Some symbiotic with land plants
-flagellate cells possesses various types and numbers of flagella inserted posteriorly

Question 2

Saprophytic

Answer 2

Breaking down dead organic materials

Question 3

Diversity of fungi

Answer 3

80,000-120,000 described, estimated 1.5M
-least explored bio diverse group

Question 4

Diversity of fungi trend

Answer 4

-typically warm and moist climates
-distance from equator and mean annual precipitation had strongest effect of fungi diversity
-ectomycorrhizal fungi most common in boreal and temperate ecosystems (trees)

-however, not fully correct as too much area was extrapolated

Question 5

What things define fungi
-nutrition
-vegetative state
-cell wall
-nuclear status
-propagules
-habitat
-ecology
-distribution

Answer 5

-heterotrophic
-non-motile mycelium of hyphae
-glucans and chitin
-eukaryotic, uni or multi nucleate
-microscopic spores produced in high numbers
-terrestrial, fresh water and marine
-saprotrophs, mutualistic symbionts, parasites
-wide

Question 6

Hyphae distinguished by…

Answer 6

Distinguished by reserve of absence of cross walls (septa)
-oomycota and zygomycota: generally aseptate hyphae, coencytic
-ascomycota and basidiomycota: septate hyphae where each segment contains 1,2 or more nuclei

Question 7

Growth forms of fungi

Answer 7

Aseptate hypha (zygomycota)

Septate branched hypha (ascomycota)

Yeast cells dividing by binary fission (ascomycota)

Yeast cells dividing by budding (basidiomycota)

Pseudohypha (ascomycota)

Question 8

Lower fungi grow as a _____

Answer 8

Thallus: walled structure where protoplasm is concentrated in one or more centres from which root-like branches (rhizoids) grow

Question 9

Obligately plant-pathogenic fungi and fungus-like organisms may grow as a naked ______

Answer 9

Plasmodium: uni or multi nucleate mass of protoplasm not surrounded by a cell wall of its own

Question 10

What is the most unique group of fungi?

Answer 10

Oomycota

-no chitin, but had cellulose

Question 11

Fungi reproduction

Answer 11

Small, asexual spores produced in large numbers

Zoospores with various types and numbers of flagella

Question 12

Single hypha produced by fusion typically have ______ nucleus per “cell”, and it known as ______

Answer 12

2

Dikaryon

Question 13

_______ may live and grow for years, and some are thought to be centuries old

Answer 13

Dikaryon

Question 14

Fungi feed by ______

Answer 14

Absorption of nutrients from the environment around them. Hyphae secrete digestive enzymes which break down the substrate.

Uptake in fungi is mediated by proteinaceous pores in plasma membrane: channels or porters

Question 15

Channels

Porters

Answer 15

Facilitate diffusion of solutes following concentration gradient (high concentration)

Use metabolic energy (H+ gradient) to accumulate the solute across the plasma membrane against its gradient (low concentration)

Question 16

1/3 of total cellular ATP used to establish ________

Answer 16

Transmembrane H+ gradient

Question 17

Uni port and symport carriers

Answer 17

Couple the inward movement of H+ with the uptake of uncharged or negatively charged solutes

Question 18

Antiports

Answer 18

Harness the outward diffusion of cations such as K+ for the uptake of other positively charged solutes

Question 19

Hyphae growth

Answer 19

-growth nearly infinitely by extension at their tips
-can reach a length of several kilometres

Question 20

________ events aggregate groups of hyphae leading to synchronized growth

_________ may influence gene expression between adjacent hyphae

Answer 20

Signalling

Secretion of chemical messengers

Question 21

Cytoskeleton in fungi

Answer 21

Microtubules involved in long-distance transport of organelles: secretory vesicles, nuclei, and positioning of mitochondria, nuclei or vacuoles

Also include actin filaments

Question 22

Proposed mechanism of hyphae growth

Answer 22

Cytoskeleton is probably responsible for pushing the hyphal tip forward

Stretch-activated Ca2+ channels concentrated in apical plasma membrane

Stretched plasma membrane admits Ca2+ ions to contact actin cap= reduce apical growth

Sequestration of Ca2+ by subapical vacuoles lowers Ca2+ resulting in relaxation of actin cap and hyphal growth

Question 23

Scaffold model of growing hyphae

Answer 23

-secretory vesicles and chitosomes (synthesize chitin) transported along microtubules from their subapical sites of synthesis
-apical body (spitzenkorper) forms around a cluster of actin filaments
-actin scaffold inside apex is linked to rivet-like integrin molecules
-apex further stabilized by spectrin molecules longing the cytoplasmic surface of the plasma membrane

Question 24

Formation of aggregates of parallel, relatively undifferentiated hyphae is coming in ______ and some _____

Answer 24

Basidiomycota

Ascomycota

Question 25

Mycelia’s strands form a ______of the cultivated mushroom agaricus Bosporus

Answer 25

Spawn

Question 26

Fungi evolved when

Answer 26

>900 mya Estimate is consistent with the discovery of fossilized hypha-like structures in sediments about 1bya

Question 27

Are fungi good fossils?

Answer 27

No Often found within plant fossils with symbiotic relationship to fungi

Question 28

Two main theories on the evolution of fungi

Answer 28

1. Old theory that fungi evolved from algae that lost chlorophyll. Green algae evolved into power fungi and red algae became ascomycota 2. Animals and fungi are closer in relation than either are to plants-both have origins to opisthokonta

Question 29

Earliest branching lineage of fungi

Answer 29

Chrytids