Mycology Flashcards
(119 cards)
1
Q
They are Monophyletic group of eukaryotic heterotrophs
Which Have characteristics intermediate between algae and protozoa
A
Myceteae or fungi
Kingdom mycota
2
Q
What are the two morphological types of of microscopic fungi
A
morphological types: yeasts and hyphae.
3
Q
branching threadlike structures of mycelia
A
Hyphae
4
Q
What are dimorphic forms of fungi
A
Yeast and mycelia forms
5
Q
What are septum and their functions
A
They are the cross walls on hyphae
Uses:
•separate cells, which may nevertheless be joined by one or more pores
• permit cytoplasmic streaming, a form of internal transport.
6
Q
What are ceonocytic hyphae and eg of organisms which have it
A
Aseptate hyphae
Eg; rhizopus
7
Q
The woven, intertwining mass of hyphae that makes up the body or colony of a mould
A
Mycelia
8
Q
Characteristics of fungi
A
Eukaryotes with true nuclei
•No chloroplast and cannot perform photosynthesis
•Have chitinous cell wall
•Cell wall prevents engulfing of solid food
•Reproduce sexually and asexually
•Vegetative body may be unicellular or multicellular
9
Q
Do fungi engulf solid food
A
No
Cell wall prevents it
10
Q
What helps in the regulation of cell division
A
Glutamates and chitin
11
Q
What is the β-1-4 polymer of N-acetyl-D-glucosamine (GlcNAc) in fungi
A
Chitin
12
Q
How is chitin produced
A
Produced by the transfer of GlcNAc from uridine diphosphate GlcNAc into chains of chitin by chitin synthase
The chitin chains are then transported to the plasmalemma and subsequently integrated into cell wall
13
Q
What is the chitin enzyme in cytosol of organelles called
A
chitosomes
14
Q
What are the major polysaccharides in cell wall and the trace amounts
A
noncellulosic glucans such as: –Mannan (polymers of mannose) –Chitosans (polymers of glucosamine) –Galactans (polymers of galactose) –Glycogen-like compounds
In trace amounts are Fucose, rhamnose, xylose and uronic acid
15
Q
What is the main structural component of the fungal cell wall,
A
Glucan
16
Q
What are the three forms of glucan
A
- β - 1,6 – glucan
- β - 1,3 – glucan
- Mixture of β - 1,3/ β - 1,6 – glucans
17
Q
Chitin is concentrated in bud scars that are areas of the cell from which a bud has detached.
A
True/ false
18
Q
What are present in 30% of the cell wall
A
Proteins and lipids
19
Q
Where do mannoproteins radiate from
A
An internal skeletal layer formed by polysaccharide composition cell wall
Read page 26
20
Q
Functions of cell wall
A
The cell wall is essential to the fungus as it;
•provides physical protection
•maintains osmotic stability
•regulates cell shape
•acts as a scaffold for proteins
•mediates cell – cell communication
•the site of a number of enzymatic reactions.
21
Q
What is located directly below the periplasmic space
A
Plasmalemma
22
Q
What is the dominant sterol in fungi cell membrane abs he it found in mammals?
A
Ergosterol
No it is not
23
Q
How thick is the cell membrane
A
(aprox. 10 nm thick
24
Q
What represent regions of rigidity in the fluidity provided by the phospholipid bilayer.
A
Sterols
Thus makes it significant in the cell membrane
25
What the the use of ergosterol
| And what will happen when it is inhibited
It’s is used to control chitin synthesis
Inhibition of ergosterol leads to general activation of chitin synthetase – excessive chitin production and abnormal growth
26
It is the repository of the DNA and also contains proteins in the form of histones
Nucleus
27
How does nucleus store proteins and extrachromosomal information
Proteins are stored in histones
•In addition to the genetic material in the nucleus the yeast cell often has extra chromosomal information in the form of plasmids
28
Where are the enzymes of the tricarboxylic acid cycle (Krebs’ cycle) located
Matrix of the mitochondrion
29
Where does the electron transport and oxidative phosphorylation occur
in the mitochondrial inner membrane.
30
What is the function of the outer membrane of mitochondrion
The outer membrane contains enzymes involved in lipid biosynthesis.
33
31
Why is The mitochondrion a semi-independent organelle
it possesses its own DNA and is capable of producing its own proteins on its own ribosomes which are referred to as mitoribosomes.
32
What are polysomes
lines of ribosomes strung together by a strand of mRNA.
33
are hollow cylindrical structures that are involved in the movement of chromosomes, nuclei and golgi vesicles containing precursors of cell wall
Microtubules
34
What assist in the movement of chromosomes during mitosis and meiosis
Spindle fibers made of microtubules
35
What are the reproductive bodies and what gives rise to them
Spores
The vegetative hyphae give rise to structures called reproductive hyphae,
•These hyphae are responsible for the production of reproductive bodies called spores
36
Why do we say fungi are heterotrophs and saprobes
They don’t produce their own food but rather on plants and animals
are saprobes; meaning that they obtain these substrates from the remnants of dead plants and animals in soil or aquatic habitats.
37
Can fungi synthesis it’s own amino acids and proteins from carbohydrates and simple nitrogenous compounds?
Yes
38
Where and under what conditions do fungi thrive in
thrive in substrates with high salt or sugar content, at relatively high temperatures, and even in snow and glaciers
39
By what means do fungi metabolize
Metabolism is generally aerobic, but some yeasts can function as facultative anaerobes( can survive with or without o2)
40
How do fungi grow and why do they grow that way
adding length rather than thickness;
•This growth pattern leads to an increase in surface area and is an adaptation to an absorptive way of life.
41
Carbohydrates are stored in?
Glycogen
42
Where do fungi get their phosphorus, inorganic ions and iron
Phosphorous: phosphate molecules
* Iron: ferric hydroxide using *siderophores*
* Inorganic ions: K+, Mg2+, SO42-, Cu2+, Zn2+ and Mg2+
43
What are the subdivision of reproductive spore production
Asexual spores are the products of mitotic division of a single parent cell. E.g. budding, fragmentation, etc
•Sexual spores are formed through a process involving the fusing of two parental nuclei followed by meiosis.
44
Fungi spore have more resistance compared to bacteria endospore true or false
False
45
What type of spore formation Arises by pinching off portions of the coenocytic cell
Asexual spore
46
What are the two types of asexual and their subclasses
* Sporangiospores(zygomyctesq)
* Conidiospores( ascomyctes)
- Microconidium
- macroconidium
- Arthrospores
- Clamydospores
- Phialospore
- Porospore
*zoospores( chytrids)
47
What is the difference between conidiospores and sporangiospores
Their free spores are not enclosed in a sack
| Have conidiophores
48
What are microconidium and macroconidium
Micro has a small single cell
Macro has large two or more cells divided by septum
Page 56
49
What are blastospores
Formed by budding of parent cell eg yeast
50
What are arthrospores
Formed by the segmentation and breaking of hyphae
51
What are clamydospores and give eg
Thick walled resting spores
| Eg. C. albicans
52
What’s a phialospore
Vase
A conidium that is budded from the mouth of a vase-shaped spore-bearing cell called a phialide or sterigma, leaving a small collar.
53
What is the name given to a spore bearing cell of a phialospore
Phialide or sterigma
54
What is a porospore
A conidium that grows out through small pores in the spore-bearing cell; some are composed of several cells.
55
What are the three sexual spores
Zygospores
Ascospores
Basiodospores
56
What are zygospores
These are sturdy diploid spores formed when hyphae of two opposite strains (called the plus and minus strains) fuse.
57
What does the zygote of a zygospore form
Sporangium
58
What brings about the development of sporangiospores in a sexual sporangium
Meiosis of diploid cells of the sporangium which results in haploid nuclei that develop into sporangiospores.
59
How are the sporangia from sexual and asexual spores similar and different
Same phenotypic structure
Different genotypes
60
Gametangia plus gamete= ?
Zygote
61
What are ascospores and how do they form
haploid spores are created inside a special fungal sac, or ascus (plural. asci).
the “male” sexual organ (antheridium) fuses with the “female” sexual organ (ascogonia).
62
What sexual spores form from
- diploid nuclei to haploid zygotes
- haploid nuclei to diploid zygote
- 4 haploid to 2 haploid
- Zygospore
- Ascospore
- basidiospore
63
What is an ascocarp
the fruiting body of the sexual phase in Ascomycota.
Some species form an elaborate fruiting body to hold the asci.
64
What are the 5 types of ascocarp
–Naked asci: these occur in simple ascomycetes; asci are produced on the organism's surface.
–Perithecia: Asci are in flask-shaped ascoma (perithecium) with a pore (ostiole) at the top.
–Cleistothecia: The ascocarp (a cleistothecium) is spherical and closed.
–Apothecia: The asci are in a bowl shaped ascoma (apothecium). These are sometimes called the "cup fungi".
–Pseudothecia: Asci with two layers, produced in pseudothecia that look like perithecia. The ascospores are arranged irregularly.
65
What are the four types of ascus
-unitunicate-operculate ascus
Unitunicate-inoperculate
bitunicate
Prototunicate
66
What are unitunicate- operculus asci
Single-walled;
–has a "lid", the Operculum, which breaks open when the spores are mature and allows the spores to escape.
–Only occur in those ascocarps which have apothecia, for instance the morels.
67
What are Unitunicate-inoperculate asci
elastic ring that functions like a pressure valve.
–Once mature the elastic ring briefly expands and lets the spores shoot out.
–This type appears both in apothecia and in perithecia
68
What are bitunicate ascus
enclosed in a double wall (thin, brittle outer shell and a thick elastic inner wall).
–When the spores are mature, the shell splits open so that the inner wall can take up water until it protrudes above the rest of the ascocarp to liberate spores.
– Bitunicate asci occur only in pseudothecia.
69
What are prototunicate asci
Prototunicate asci
–mostly spherical in shape and have no mechanism for forcible dispersal.
–The mature ascus wall dissolves allowing the spores to escape, or it is broken open by other influences, such as animals.
–Asci of this type can be found both in perithecia and in cleistothecia
70
What are basidiospores
These are haploid sexual spores formed on the outside of a club-shaped cell called a basidium.
71
Where are basidia located in basidiospores(mushrooms)
Along the gills in the mushroom
| And are often dark
72
What is the function of the fleshy part of mushroom
A fruiting body to protect and help disseminate sexual spores
73
Ate yeast larger than bacteria
Yes
| 5-10 micrometers
74
An example of yeast that undergoes binary fission
Schizosaccharomyces pombe
75
What are the types of asexual reproduction yeast does
Budding and binary fission
76
What is the name given to a chain of yeast formed when buds remain attached in a row
Pseudohyphae
77
How are yeast texa distinguished
–the presence or absence of capsules,
–the size and shape of the yeast cells,
–the mechanism of daughter cell formation (coniodiogenesis),
–the formation of pseudohyphae and true hyphae,
–the presence of sexual spores
78
How are yeast genus identified
Morphology
79
How are yeast species identified
–Ability to ferment and assimilate various carbon sources
–Ability to utilize nitrate as source of nitrogen
–Morphology
80
What are moulds
fungi that do not form fruiting bodies visible to the naked eye.
•It excludes toadstools and mushrooms.
81
Most moulds consist of a tangled mass (mycelium) of filaments or threads (hyphae)
True
82
How do mound hyphae elongate
process called apical elongation
| –Requires careful balance between cell wall lysis and new cell wall formation
83
moulds may be differentiated for specialized functions, e.g. absorption of nutrients or reproduction.
True or f
True
84
Some mould produce special sac-like cells called sporangia which produces spores
True or f
True
The spores are called sporangiospores.
Sporangia are formed on special hyphae called sporangiophore.
85
What is dimorphism in fungi
How do they form
Give eg
Dimorphism is when fungi express phenotypically two different morphologic forms
The do this to correlate with their saprophytic and parasitic modes of growth
Eg. Dimorphic fungi grow as mould at room temperature in the laboratory and as budding yeast or spherules either in tissues or at 37oC
86
What factors contribute to expression of dimorphism in fungi
- high incubation temperature
–high carbon dioxide concentration
–pH
–Presence of cysteine and other sulfhydryl – containing compounds
87
What are the four major phyla of fungi
* Zygomycota and Chytridiomycota
| * Ascomycota and Basidiomycota (‘Higher Fungi’)
88
What are Deuteromycota or Fungi Imperfecti??
fungi which do not fit into the commonly established taxonomic classifications of fungi because their sexual form of reproduction has never been observed
89
What are the 6 classes of kingdom fungi
| BADOTU
* The Class Oomycetes contains the mildews and water moulds
* The Class Ascomycetes contains the mildews, some moulds and most yeast species (including saccharomyces cerevisiae)
* The Class Basidiomycetes contains the mushrooms and bracket fungi
* The Class Teliomycetes contains the rust fungi (plant pathogens)
* The Class Ustomycetes contains the smuts (plant pathogens)
* The Class Deuteromycetes contains species such as Aspergillus, Fusarium and Penicillium
90
```
What class is
saccharomyces cerevisiae
```
rust fungi
smuts
Aspergillus, Fusarium and Penicillium
Ascomycetes
Teliomycetes
Ustomycetes
Deuteromyctes
91
members of the group are of great importance in the formation of a mutualistic association with plant roots known as a mycorrhiza
Zygomycota
| That is why there are found in soil and dead organic matter
92
Members of this phyllum are characterised by the formation of a dormant form, the zygospore
Zygomycota
93
What are coenocytic hyphae and which fungi has them
Coenocytic hyphae are nonseptate, also called aseptate, meaning they are one long cell that is not divided into compartments.
Eg Zygycota, Chytridiomycota
94
Members form dicaryon
All fungi phyla except chytrids
95
structure formed by two cells whose contents, but not nuclei, have fused.
may be regarded as an intermediate stage between the haploid and diploid conditions.
Dicaryon
96
believed to have been the first of the fungal groups to diverge from a common ancestor many millions of years ago.
•They differ from all other fungal groups by possessing flagellated zoospores
Chytridiomycota
97
What made chytrids move from beings Protista to Fungi
Fungi were defined by their lack of flagella, so the chytrids were assigned to the Protista.
However, molecular evidence, including the possession of a chitinous cell wall, suggests that it would be more appropriate to place them among the Fungi
98
What fungi parasites have at least partially responsible for the dramatic decline in frog populations in certain parts of the world.
Chytrids
99
Where do chytrids dwell
* Some live saprobically on decaying plant and animal matter,
* others are parasites of plants and algae.
* Another group live anaerobically in the rumen of animals such as sheep and cattle.
100
This phyla are characterised by the production of haploid ascospores through the meiosis of a diploid nucleus in a small sac called an ascus.
•For this reason they are sometimes called the sac fungi or cap fungi.
Ascomycota
101
Many of the fungi that cause serious plant diseases such as Dutch elm disease and powdery mildew belong to this group.
•They include some 30 000 species, among them yeasts, food spoilage moulds, brown fruit rotting fungi and truffles.
Ascomycota
102
What is lichen
•A lichen is formed by the symbiotic association of a fungus (usually an ascomycete) and an alga or cyanophyte.
Around half of ascomycote species exist in associations with algae to form lichens.
103
What distinguishes ascomycotaycelia from zygomyctes
Septate cross walls in hyphae
104
What is a pycnidium
A flask-like structure which sometimes protects conidia
105
In sexual reproduction of ascomytes
| What are the hyphae involved
The ascogonium (− -strain) and antheridium (+ -strain).
106
What is plasmogamy
cytoplasmic fusion
107
What phylum exhibits this ; hyphae are septate, i.e. partitioned off into separate cells, but each cell is dicaryotic, having a nucleus from each parental type
Ascomycota
108
Asexual reproduction occurs much more frequently in basidiomycetes than in the other types of fungi.
False
When it does occur, it is generally by means of conidia or sometimes segmentation
109
Which phyla exhibits the clamp connection; device for ensuring that as growth continues, each new cell has one nucleus from each of the parent mating strains.
Basidiomycota
110
Which phyla exhibits this;
| Stalk formation and upward growth is extremely rapid; a stalk or stipe of 10 cm can be formed in only about 6–9 hours.
Basidiomycota
The growth is initially towards light (positive phototropism) and then upward (negative geotropism).
111
What is used to identify fungi in the lab
asexual spore-forming structures and spores are usually used to identify organisms to the level of genus and species.
112
Examples of media for cultivating fungi are?
cornmeal, blood, and Sabouraud’s agar.
113
Why is Sabouraud’s agar useful in isolating fungi from mixed samples
because of its low pH, which inhibits the growth of bacteria but not of most fungi.
114
What is the economic importance of these filamentous fungi
1. Agaricus bisporus
2. Aspergillus, Pemilcillium spp.
3. Aspergillus + Saccharomyces sp.
4. Fusarium graminearum
5. Penicillium chrysogenum
6. ‘ ‘ notatum
7. ‘. ‘ roqueforti
1. Edible mushroom
2. Enzymes( lipase catalase amylase)
3. Sake( rice wine)
4. Single cell protein
5. Penicillin production
6. Enzyme ( glucose oxidase)
7. Cheese flavoring ( Roqueforti blue cheese)
115
What is the economic importance of these yeast
1. Pichia sp
2. Sacharromycae cerevisae
1. Gene expression system
2. Baker’s yeast brewers yeast
Enzyme ( invertase)
Gene expression system
116
What yeast is the most frequently encountered human fungal pathogen, being responsible for a wide range of superficial and systemic infections.
C. albicans
117
the dominant fungal pulmonary pathogen of humans and generally presents as a problem in those with pre-existing lung disease or damage.
The mould Aspergillus fumigatus
They may also affect the brain, kidneys and sinuses depending upon the level of immunocompromise of the individual.
118
What are superficial infections
They include oropharyngeal and genital conditions
•Oropharyngeal: Occurs predominantly in HIV - positive individuals, geriatric patients and premature infants and may arise when a weakened or immature immune system is present.
•Genital candidosis: Very common and approximately 75% of women are affected by vulvovaginal candidosis (VVC) during their life.
➢A further 5-12% suffer from recurring bouts of infection over a prolonged period of time.
119
Egs of principal dermatophytic fungi and diseases they cause
are Trichophyton , Microsporum and Epidermophyton species.
* athlete’s foot and
* ringworm
