Fungi

Question 1

What are some examples of fungi?

Answer 1

Moulds. Yeasts. Mushrooms. Toadstools.

Question 2

What is the definition of a fungi?

Answer 2

Unicellular, multicellular or coenocytic. Heterotrophic. Eukaryotic. Do not contain chlorophyll. Form rigid cell wall containing chitin and/or cellulose.

Question 3

Why is the taxonomy of fungi changing?

Answer 3

Genetic comparisons. Phylogeny determined by rRNA analysis.

Question 4

What are some funal structures in the macroscale?

Answer 4

Hyphal growth forms. Hyphae. Mycelium. Fruiting bodies.

Question 5

What are the hyphal growth forms?

Answer 5

• Each hypha is a tube, cytoplasm surround by cell wall

- Could be aseptate or septate

Question 6

What is aseptate?

Answer 6

Coenocytci - several nuclei found in one ‘super cell’

Question 7

What is septate?

Answer 7

Hyphae divided by septa - single nucleus

Question 8

What can hyphae exhibit?

Answer 8

Apical growth (elongat their tips)

Question 9

What are the 2 forms of mycelium?

Answer 9

Aerial mycelium - reproduction. Vegetative mycelium - penetrates food source.

Question 10

What is an example of arial hyphae?

Answer 10

Mouldy load of bread

Question 11

What is a unicellular growth form of fungi?

Answer 11

Yeasts

Question 12

How do yeasts replicate?

Answer 12

Binary fission or budding

Question 13

What is budding?

Answer 13

Outgrowth from side of cell. Gets bigger and reaches parent size. Breaks off leaving a scar. Can only reproduce a set number of times

Question 14

What are dimorphic forms?

Answer 14

Show both hyphal and unicellular forms

Question 15

What are some fungal structures on the microscale?

Answer 15

Cellular organelles. Cell walls - chitin. Ergosterol.

Question 16

What is chitin?

Answer 16

Long polymer of N-acetylglucosamine

Question 17

WHy use ergosterol instead of cholestrol?

Answer 17

Establish proper membrane permeability and fluidity

Question 18

What is the purpose of fungal spores?

Answer 18

Dispersal. Survival. Sexual Reproduction.

Question 19

What are some sexual spores?

Answer 19

• Ascospores
• Basidiospores
• Zygospores

Question 20

What are some asexual spores?

Answer 20

Blastospores = simple structure, budding
Chlamydospores = resting spore, found in middle of hyphae, nutrient
Arthrospores = hypha fragments into individual spores
Conidiospores = formed by septation and fragmentation of existing hypha
Sporangiospores = spores produced in a sac (sporangium) at end of fruiting bodies - they pop out

Question 21

What is meant by hetertrophic?

Answer 21

require one or more carbon compounds as a carbon source

Question 22

What is meant by chemo-organotrophs?

Answer 22

Obtain energy from organic compounds

Question 23

What do Saprophytes do?

Answer 23

They are responsible for decay and recycling organic material

Question 24

What do exoenzymes do?

Answer 24

Break down carbon sources external to the cell and uptake products

Question 25

Describe Lignin Degredation.

Answer 25

• Accounts for 50% of all biomass on the planet
• Complex polymer
• Lots of carbon
• Extracellular peroxidases to break bonds within lignin to produce smaller molecules that can be absorbed and used

Question 26

How do fungi reproduce?

Answer 26

Sexually or asexually - spores can be used

Question 27

What are the 2 forms of the fungal nuceli?

Answer 27

Haploid - one. Diploid - two.

Question 28

How long are they in each stage for?

Answer 28

Mainly in haploid. Cytoplasmic fusion can occur well before nuclear fusion (diakryon)

Question 29

Describe how fungi reproduce sexually.

Answer 29

• Haploid, diploid and dikaryotic phases

- Heterothallic or homothallic

Question 30

What is heterothallic?

Answer 30

Some fungi need to mate with another individual of the opposing mating type

Question 31

What is homothallic?

Answer 31

Some that have hyphae with ‘female’ and ‘male’ in the same aggregate can fertilise themselves

Question 32

Describe yeast reproduction

Answer 32

• Exist in haploid or vegetative state
• Two yeast of different mating types fuse to form diploid form
• Have to be opposing types

Question 33

What interactions are there between fungi and humans?

Answer 33

Causes diseases - most harmless, tend to be oppurtunistic pathogens, serious infection = rare

Question 34

How do fungi cause disease?

Answer 34

Hypersensitivity - allergic reaction. Mycotoxins (eg egot poisoning)

Question 35

What is mycosis?

Answer 35

Infection of tissue - skin, hair, nails. eg athletes foot

Question 36

What is systemic mycosis?

Answer 36

Attacks deeper tissues. eg candidiasis

Question 37

How can we control fungal disease?

Answer 37

• Difficult to get rid of

- Antibiotics exploit differences but antifungal agents likely to have effects on humans and can develop resistance

Question 38

What are the potential targets of antifungal agents?

Answer 38

Cell wall synthesis
Target how ergosterol is made
Membrane functions
Nucleic acid synthesis

Question 39

What is Entomopathogenic fungi?

Answer 39

Fungi that infects insects

Question 40

What can Entomopathogenic be used for?

Answer 40

To control plant pests

Question 41

What are zombie ants?

Answer 41

Gets into the brains of Carpenter Ants
Climbs up stem of the plant and bites the lead → lockjaw
Ant dies and produces ascospores
Spores fall on the ants below and infects them
The fungus is infected by another fungus which limits it

Question 42

How to fungi infect plants?

Answer 42

Production of degradative enzymes
Destruction of plant growth regulators (gibberellins)
Toxins which interfere with cell membranes and mitochondria
Altering metabolic activities of plant
Blocking water transport and transpiration

Question 43

What is the effect of fungal diseases on plants?

Answer 43

Death or impairment of plant function

Question 44

What are the different growth forms of fungi?

Answer 44

Hyphal - septate and aseptate. Unicellular.

Question 45

How do fungal pathogens cause disease?

Answer 45

Hypersensitivity. Mycosis. Mycotoxins.