Lesson 23- Fungi Flashcards
What is mycology?
The study of fungi
What type of cell wall are fungi made out of and do they have a nucleus and membrane bound organelles?
Chitin & Glucan
yes, they are eukaryotic.
what is Chitin made out of?
N-acetyl glucosamine organized into microfibrils (similar to plants)
What are the 2 basic forms of fungi? Briefly Describe them
- Yeast- unicellular, usually divide by budding (asexual reproduction)
- Mould- multicellular colonies that consist of filamentous, cylindrical structures called hyphae (enhance ability to absorb nutrients)
Some fungi are dimorphic
how do terrestrial fungi get to their food source, and digest the nutrients?
By growing towards it (they are immobile) Secreting exoenzymes, digesting the nutrients into simpler molecules, and absorbing them (saprotrophs)
*most fungi are saprotrophs
Where can fungi be found?
they are ubiquitous (water, air, soil, animals, etc.)
Where can fungi be found in the body, and are they harmful?
- mouth
- Skin Respiratory tract
- Gastrointestinal tract
- Genital tract
Many are part of normal flora ( most are harmless) 1000’s or species exist, only a few are harmful
Describe some roles of fungi
- Saccharomyces (bakers yeast) produces bread & ethanol
- Penicillin species produce cheese & antibiotics
- Cladosporium Alternaria- environmental fungi that cause allergy
What are the dimensions of yeast & their method of respiration
1-5μm wide &5-30 5μm long
Facultatively anaerobic
Give an eg of a dimorphic yeast
Candida albicans (it is commensals)
What is the mode of reproduction of yeast?
Most by asexual budding. Some, like Sacchaeomyces (Bakers yeast) can reproduce sexually using sexual spores
Give an eg of yeast that have capsules, and state their function.
cryptococcus species
Help in adhesion &resistance to phagocytosis
What is the size of the diameter of molds?
State the different types of Hyphae
2-10 μm
- Septate hyphae (cross wall between every nucleus)
- Non septate hyphae
- Sparsely septate hyphae
how do molds respire and grow?
Using Oxygen (Obligate aerobes) Grow by elongation at tips
what is the network of hyphae termed?
Mycelium
describe the 3 types of asexual spore formation of moulds
- Arthrospores- arise from fragmentation of vegetative hyphae
- Sporangiospores- Spores in a sac that burst when environment is suitable for germination
- Canidiospores- spores borne externally on aerial hyphae
Describe Candida albicans and it’s corresponding disease
- Commensals dimorphic yeast
- Normal flora in the mucous membranes (mouth & vagina)
- Corresponding disease is Candidiasis - Thrush (in mouth) vaginitis in vagina
Describe Cryptococcus & it’s corresponding disease
- oval shaped yeast with capsule, present in soil
- Bird droppings allow the fungi to grow.
- Infection begins in the lungs, when it is inhaled from dried droppings
- May spread lungs-> Blood -> Meninges, causing Meningoencephalitis
Describe dermatophytes & what they cause
- moulds that reproduce via asexual spores termed Micronidia & Macronidia (use Keratin as their Nitrogen/ energy source)
- cause superficial nail, hair, and skin infection For eg, ringworm caused by exoenzymes degrading keratin & collagen of the skin.
- common among children playing outside
describe histoplasma and what it causes
- dimorphic mould that may cause severe systemic mycoses
- grows as a mould outside body, and as yeast in the body
- Infection occurs when inhaling the spores In immunosupressed ppl, it may result in lung infection spreading to other organs
Is It true that only pathogenic fungi can result in infection?
No, opportunistic infections may also arise from ppl who are immunocompromised (HIV, Cancer, transplant recipients, etc) Infection usually starts with infection of spore such as the Aspergillus species, eg (Aspergillus conidiospores)
