Ch. 31 Fungi

Question 1

What are hyphae?

Answer 1

Filaments extending from multicellular fungi into their surroundings.

Question 2

Function of hyphae?

Answer 2

They secrete enzymes that break down organic matter. They then absorb the released nutrients from broken down organic matter.

Question 3

Function of spores in fungi?

Answer 3

Spores germinate and grow when conditions are favorable.

Question 4

Are fungi hetero or autotroph?

Answer 4

Fungi are heterotrophs that absorb nutrients from the outside.

Question 5

How do fungi break down complex molecules into smaller organic compounds?

Answer 5

Hydrolytic enzymes

Question 6

What roles can fungi play in ecosystems?

Answer 6

Decomposers, parasitic, and mutualistic

Question 7

Common body structures of fungi:

Answer 7

Multicellular filaments and single cells (yeasts).

Question 8

Environment of yeasts?

Answer 8

Moist environments with soluble nutrients like sugars/amino acids.

Question 9

Purpose of chitin in hyphae walls?

Answer 9

Chitin-rich walls prevent cells from lysing during osmotic pressure that builds up during nutrient absorption.

Question 10

Hyphae are divided into cells by _______, which have large pores that allow movement of organelles between individual cells.

Answer 10

Septa

Question 11

__________ _______ lack septa; they have thousands of nuclei in a continuous cytoplasmic mass

Answer 11

Coenocytic fungi

Question 12

Mycelium =

Answer 12

Branched hyphae

Question 13

Why are mycelium structures efficient?

Answer 13

They maximize surface-to-volume ratio.

Question 14

What are haustoria?

Answer 14

Specialized hyphae in plant parasites that allow extraction of nutrients from plants.

Question 15

Specialized hyphae of predatory fungi for feeding on live animals are called:

Answer 15

Snaring loops or sticky nodules

Question 16

Fun fact: hyphae can wrap around things like nematodes, trap them, and eventually kill them.

Question 17

Mutualistic fungi have specialized hyphae to exchange nutrients with their plant hosts. Name one.

Answer 17

Arbuscules: they penetrate cell walls but not cell membrane.

Question 18

Mycorrhizae =

Answer 18

Mutually beneficial relationships between fungi and plant roots. Mycorrhizal fungi give phosphate ions/minerals to plants. Plants give organic nutrients to fungi.

Question 19

What are the 2 types of mycorrhizal fungi and describe them.

Answer 19

Ectomycorrhizal fungi form sheaths of hyphae over root surface and into extracellular spaces of root cortex.

Arbuscular mycorrhizal fungi extend arbuscules through root cell wall and into tubes formed by invagination of root cell plasma membrane.

Question 20

Most _________ _______ depend on mycorrhizae.

Answer 20

Vascular plants. Mycorrhizal fungi colonize soils by producing haploid spores.

Question 21

Fungi: sexual or asexual reproducers?

Answer 21

Fungi propagate by producing spores sexually or asexually.

Question 22

How can spores germinate?

Answer 22

In moist places w/ food, they will germinate and form new mycelia.

Question 23

Fungal nuclei and spores are usually diploid/haploid?

Answer 23

Haploid

Question 24

Sexual reproduction requires the fusion of hyphae from different/same mating types?

Answer 24

Different

Question 25

Many fungi use sexual signaling molecules called _________ to communicate their mating type.

Answer 25

Pheromones

Question 26

Plasmogamy =

Answer 26

The cytoplasmic union of 2 parent mycelia.

Question 27

Heterokaryic

Answer 27

Mycelia with coexisting, genetically different nuclei.

Question 28

Dikaryotic mycelium =

Answer 28

When haploid nuclei pair off 2 per cell

Question 29

In most fungi, fusion of haploid nuclei of parents is delayed!

Answer 29

Hours, days, or centuries may pass before the nuclei fuse. When haploid nuclei fuse, a diploid cell, ie. zygote, is produced.

Question 30

Karyogamy -

Answer 30

The process of 2 haploid nuclei fusing and formation of a diploid nucleus.

Question 31

What contributes to genetic variation in fungi?

Answer 31

Karyogamy and meiosis.

Question 32

How do molds reproduce?

Answer 32

They produce haploid spores asexually and form “fuzzy” mycelia.
Ex) penicillium (commonly decomposes food)

Question 33

How do single-celled yeasts reproduce?

Answer 33

They reproduce asexually through simple cell division or pinching/budding off a parent cell.
Ex) yeast Saccharomyces cerevisiae

Question 34

Deuteromycetes -

Answer 34

Yeasts and filamentous fungi that have no known sexual stage.

Question 35

Fungi and animals are more closely related to each other than either group is to plants or most other eukaryotes

Answer 35

Fungi ancestor was flagellated protist. Opisthokonts clade includes fungi, animals, and protistan relatives evolved from unicellular flagellated ancestor.

Question 36

What group are fungi most closely related to?

Answer 36

Single-celled protists
Ex) Nucleariids are closely related amoebas that feed on algae and bacteria.

Question 37

What group of protists are animals most closely related to?

Answer 37

Choanoflagellates

Multicellularity evolved independently in fungi & animals.

Question 38

Fossil evidence supports the formation of __________ relationships between fungi and early plants.
a) parasitic
b) mutualistic
c) commensalism
d) competition

Answer 38

mutualistic

Question 39

____ genes require for mycorrhizal formation were present in early plants.

Answer 39

Sym

Question 40

Know the fungal phylogeny!!

Answer 40

Cryptomycetes
Microsporidians
Chytrids
Zoopagomycetes
Mucoromycetes
Ascomycetes
Basidiomycetes

Question 41

What 2 phylums from a sister group and Basal Fungi?

Answer 41

Cryptomycetes (phylum Cryptomycota) and Microsporidians (phylum Microsporidia)

Question 42

Tell me about Cryptomycetes group.

Answer 42

Found in soils, marine, and freshwater habitats.
They are both aerobic and anaerobic that are unicellular with flagellated spores.
They have chitin cell walls

Many are parasites of protists/fungi
ex) Rozella

Question 43

Tell me about Microsporidians group.

Answer 43

Unicellular parasites of protists and animals, INCLUDING humans.
Have chitin cell walls w/ reduced mitochondria and non flagellated spores

ex) Nosema ceranae = parasite of honeybees that contribute to Colony Collapse Disorder

Question 44

Tell me about Chytrids (phylum Chytridiomycota)

Answer 44

Found in lakes, soil, and marine habitats.
Function: decomposers, parasites, mutualists.
All chytrids have flagellated spores = zoospores (flagella attached to spherical spore)
Have chitin cell walls
Some are single-celled, others from colonies.

Question 45

Tell me more about Zoopagomycetes (phylum Zoopagomycota)

Answer 45

Chitin cell walls
Parasites/commensal symbionts of animals
Parasites of other fungi/protists
Form filamentous hyphae and reproduce asexually via non flagellated spores (wind-dispersed).
Reproduce sexually, form durable structure (zygosporangnum) to house/protect zygote

Can induce behavioral changes in insects they parasitize.

Question 46

Tell me about Mucoromycetes (bread molds).

Answer 46

Chitin cell walls
Molds are important decomposers.
Live has parasites, pathogens, or mutualists w/ plants (including mycorrhizae).
Ex) Rhizopus stolonifer (black bread mold, mold that breaks down bread)
Ex) Pilobolus

In deteriorating conditions (most of the food is consumed) sexual reproduction occurs
Fusion between mycelia of different mating types (plasmogamy) produces a zygosporangnum.
Coenocytic hyphae spread and penetrate the surface, absorbing nutrients from rotting food.

Question 47

Mucoromycetes Asexual Reproduction

Answer 47

1. Sporangia develop on hyphae, asexually reproducing air-dispersed spores
2. Zygosporangia = metabolically inactive + resistant to extreme conditions (freezing/drying)
3. Once conditions are good, MEIOSIS germinates zygosporangium into sporangium
4. Sporangium releases genetically diverse haploid spores

Question 48

Mucoromycetes also includes an arbuscular mycorrhizae-forming clade of fungi called ________.

Answer 48

Glomeromycetes

~85% plant species have mutualistic partnerships w/ arbuscular mycorrhizae

AMF = BENEFICIAL
Arbuscular mycorrhizal fungi (AMF) = soil microbes that colonize plant root and connect the plant and the substrate, help in production of plant growth hormones, increase nutrient avail….

Question 49

Tell me more abt Ascomycetes (sac/cup fungi)

Answer 49

Chitin cell walls
Marine, freshwater, terrestrial habitats
Form varies from unicellular yeasts to elaborate cup fungi/morels
Includes plant pathogens, decomposers, and symbionts

Are called sac/cup fungi bec saclike asci in which spores form
During sexual stage ascomycetes produce fruiting bodies called ascocarps (cup) that contain spore-forming ascidians (sac)

Question 50

25% ascomycete species form _______, symbiotic associations w/ green algae or cyanobacteria

Answer 50

Lichens

Question 51

Ascomycetes reproduce asexually using asexual spores called _______.
Where are these asexual spores produced?

Answer 51

Conidia, produced at conidiophores (ends of specialized hyphae).

Question 52

In Ascomycetes SEXUAL REPRODUCTION, _______ fuse w/ ______ of a mycelium from a different mating type.

Dikaryotic cells (2 nuclei in each cell) are formed, each containing 2 haploid nuclei, one from each parent.

Asci form at tips of dikaryotic hyphae, and karyogamy (fusion of 2 nuclei) and meiosis occur within asci

Ascospores develop and are discharged from ascocarp

Answer 52

conidia, hyphae

reminder: conidia = asexual spores