Eukaryotic Microbes 2: Fungi Flashcards Preview

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Flashcards in Eukaryotic Microbes 2: Fungi Deck (23)
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1
Q

Where are fungi found?

A
  • Everywhere!
  • aquatic
  • terrestrial
  • parasites of plants
  • parasites of animals and humans
2
Q

Explain the fungal nucleus.

  • size
  • ploidy
  • unique features of the fungal nuclei?
A
  • double membrane bound organelle ranging in size from 1-2um to 20-25um in diameter
  • most are haploid with 6-20 chromosomes
    L> some are naturally diploid
    L> others alternate between the two
    -membrane remains intact during mitosis
    L> no clear metaphase plate.
3
Q

Fungal cytoplasmic organelles?

A
- plasma membrane
L>phospholipid bilayer -> anchorage for enzymes/proteins such as chitin synthases or glucan synthases  
L> contains ergosterol 
- chitosomes 
L> microvesicles for chitin synthesis
4
Q

Explain the purpose of the fungal cell wall.

A
  • structural barrier
  • environmental interface
    L> protects against osmotic lysis
    L> contains pigments for protection
    L> binding site for molecules
    L> mediates interactions with other organisms.
5
Q

Describe the composition of the fungal cell wall.

A
  • Mannan
  • protein
  • B-1,3-glucan
  • B-1,6-glucan
  • chitin
  • *58%= glucan
  • *36%= Mannan
    • 4% = protein
    • 2 %= chitin
    • be able to draw the cell wall and label these areas.
6
Q

With respect to the fungal cell wall what does Mannan give it?

A
  • a detectable signature via:
    1. O-Mannan -> composed of alpha 1,2 mannose and beta 1,2- mannose.
    2. N-Mannan -> composed of alpha 1,2 mannose, beta 1,2- mannose, N acetyl glucosamine, beta 1,4 mannose, alpha 1,6 mannose, alpha 1,3 mannose and Phosphate…. aka IT IS MORE COMPLEX
7
Q

The growth of fungi:

- What can they look like ( three groups)

A
  1. Filamentous
    L> moulds and mushrooms
  2. Yeasts (circular shape)
  3. Dimorphic fungi (mixture)
8
Q

Describe filamentous fungi!

- what is the main structure?

A
  • Hyphae: rigid tubes containing cytoplasm. Interconnected compartments not individual cells
  • long filaments of cells joined end to end = hyphae
9
Q

Filamentous fungi:

- Describe the two types of hyphae.

A
  1. Septate Hyphae
    L> joint cells have distinct separations called septa, containing pores (to share cytoplasm)
  2. Coenocytic Hyphae
    L> consists of fused cells, multinucleated
10
Q

Filamentous fungi:

- function of septa?

A
  • offers structural support

- enables differentiation by dividing hyphae into different cells

11
Q

Filamentous Fungal growth:

typically goes _____ to ____.

A
  • spore to hyphae
12
Q

Filamentous Fungal growth:

-hyphae typically grow in what fashion?

A
  • by apical growth : extension at the tip
13
Q

Filamentous Fungal growth:

- what is a mass of hyphae called?

A
  • mycelium –> plural = mycelia
14
Q

Filamentous Fungal growth:

- Explain vegetative and aerial hyphae.

A
  • vegetative hyphae:
    L> grow along the surface , obtain nutrients
  • Aerial hyphae:
    L> stick up from the mycelium, spores for reproduction
15
Q

Explain the tropisms of hyphal tips.

A
  • they exhibit it to many substances
    L> Ex: nutrients, amino acids, volatile metabolites, sex pheromones and light
    L> examples species = Phycomyces blakesleeanus (phototropism I believe- double check)
16
Q

Yeast:

- explain their characteristics.

A
  • non-filamentous, unicellular, ovaloid
  • facultative anaerobes
    L> aka ferment carbohydrates into alcohol and carbon in the absence of oxygen.
17
Q

Yeast:

- explain budding yeast.

A
  • divide by producing outgrowth called a bud
  • bud enlarges and separates from mother cell (vegetative cell)
  • if budding fails = pseudohyphae
18
Q

Yeast:

- explain true hyphae and pseudohyphae

A
  • True Hyphae: cells tightly attached by shared walls, cytoplasm joined via pores.
  • Pseudohyphae: daughter cells remain attached to the mother cell but do NOT share cytoplasm (formed via the failed attempt at budding)
19
Q

Yeast:

- Explain fission yeast.

A
  • division by elongation of mother cell and mitosis
  • daughter cells separate by the formation of septa in the centre
    ex: Schizosaccharomyces pombe
20
Q

Yeast:

- explain dimorphic yeast.

A

-grows as multicellular hyphal or as unicellular yeast depending on the conditions

21
Q

Several Pathogens of humans exhibit dimorphism. Give three examples.

A
  1. Candida albicans
  2. Histoplasma capsulatum
  3. Mucor circinelloides
22
Q

Dimorphism occurs in response to a variety of environmental factors. Apply this statement to the following three species:

  1. Histoplasma capsulatum
  2. Candida albicans
  3. Mucor circinelloides
A
  1. 27C = filamentous; 37C= yeast
  2. human body = filamentous
  3. oxygen = filamentous; hypoxia = yeast
23
Q

Approx how many species?

A

1.5 million