Fungi Intro

Question 1

• Characteristics of fungal cells

Answer 1

eukaryotic nucleus
mitocondria, ER
Bi layered cell membrane (innermost layer)
cell wall
(cell size and volume bigger than bacteria)

Question 2

fungal cell membrane made of?

fungal cell wall made of ?

Answer 2

cell membrane: Ergosterol (target for many drugs)

Cell wall: Chitin, gluons, mannans, proteins

Question 3

-chemical description of fungal metabolism

Answer 3

heterotrophs– incapable of producing their own energy

saprophytes- decompose dead/ dying material to use as food

[ so if we become immunosuppressed we are their targets / with some exceptions]

Question 4

-morphology of fungi: Mycelia

hyphae

Answer 4

mycelia- multicellular colonies composed of clumps of intertwined branching hyphae

hyphae grow by longitudinal extension and produce spores

Question 5

-requirements for growth of fungi in lab

Answer 5

mold: 25 C
yeast: 37 C (on Saborauds dextrose agar)

• takes 4-6 weeks to grow
  antibiotics added to inhibit bacterial growth

Question 6

yeast v mold

Answer 6

yeast: single cells
mold: multicellular filamentous colonies

Question 7

-monomorphic

Answer 7

can grow as yeast or mold but not both

Question 8

-dimorphic

Answer 8

can grow as yeast and mold depending on temperatures
yeast- at body
mold- room temp

Question 9

septa hyphae v coenocytic hyphae

Answer 9

septa hyphae- divided into individual cells by septums
- septums have pores to allow passage of organelles
coenocytic hyphae- non septate- with continuous mass of cytoplasm

Question 10

arthrospores

Answer 10

hyphae segments formed by fragmentation of hyphae

Question 11

chlamydospores

Answer 11

thick walled spores (little circles) formed terminally of within hyphae segments

Question 12

conidiophores

Answer 12

formed at the tops of hyphae aka as microconidia

Question 13

sporangia

Answer 13

spherical sac like structures with sporangiospires

Question 14

-kingdom classification of fungi and protozoa

Answer 14

fungi- Eukaryotic heterotroph

protozoa= eukaryotic

Question 15

-how are fungi assigned their taxonomy?

Answer 15

based on their mode of sexual spore formation/ analysis of their DNA

Question 16

four fungal phylum

Answer 16

ascomycota
basidiomycota
zygomycota
deuteromycota

Question 17

-Ascomycota

Answer 17

sac like structures
ascospore formation *

Sexual

Question 18

• basidiomycota

Answer 18

basidiospore in club shaped structure
(mushrooms, toad stools)

Sexual

Question 19

• zygomycota

Answer 19

conjugation ( sexual reproduction where the tips of multinucleate hyphae come together and form a zygospore)

Sexual

Question 20

• Deuteromycota

Answer 20

form conidya!!!

Asexual reproduction*

Question 21

how are fungi disseminated

Answer 21

Asexual spores

Question 22

how do fungi reproduce

Answer 22

Asexual budding (division of one cell into two cells) 
fragmentation (pieces of hyphae grow) 
spore formation (haploid Cells)

Question 23

fungal pathogenic fungi are considered?

Answer 23

chemoheterotrophic- bc they obtain carbon compounds from

• non living organic material (sacrophytes)
• living tissue ( symbionts)

Question 24

symbiont fungi are either?

Answer 24

necrotrophic- facultative pathogens that live on damaged tissue
biotrophic- obligate live on living tissues

Question 25

virulence factors of fungi

Answer 25

extracellular enzymes- proteases and elastase released at advancing edge of the lesion cause host cell damage and lysis

Question 26

Mannan in virulence

Answer 26

glycoprotein component of fungal cell walls - surpasses lymphoblast formation - inhibits lymphocyte proliferation - inhibits keratinocyte proliferation (slowing epidermal turnover) to allow more persistent chronic infection

Question 27

avirulence fungi v virulent fungi

Answer 27

avirulent - have lower growth rate due to lack of invasive enzymes virulent- normal growth rate virulence is controlled by gene expression during infections

Question 28

mycotoxins

Answer 28

released into environment and act as allergens cause granuloma disease no classic exotoxins produced in vivo

Question 29

melanin virulence

Answer 29

interferes with oxidative killing by neutrophils or macrophages

Question 30

fungal infections are associated with?

Answer 30

immunocompromised patients bc we normally have high level of innate immunity and T cell mediated immunity *

Question 31

patient with severe systemic fungal diseases havE?

Answer 31

neutropenia depressed THI response-- deficiency in neutrophils and t cell mediated immunity (abs don't help to this immunity)

Question 32

laboratory diagnosis of fungi

Answer 32

KOH PAS Giemsa Nigrosin stain

Question 33

KOH

Answer 33

``` # 1 used- quick and inexpensive (50% accurate) human tissue elements are dissolved, leaving only fungal elements- conidia or hyphae ```

Question 34

PAS stain

Answer 34

Periodic Acid Schiff stain stains polysaccharides found in cell walls of mold and yeast (99%)accurate aldehyde groups bind to basic fuschin and stain fungal elements red

Question 35

giemsa stain

Answer 35

used for intracellular structures* | shown inside as blue colored

Question 36

Nigrosin stain

Answer 36

used to demonstrate capsules around cells

Question 37

homothallic v heterothallic reproduction

Answer 37

homo- cells from same zygomycota colonies engage heterothallic- cells from two different colonies (+) and (-) engage

Question 38

pseudohyphae

Answer 38

long elongated yeast cells yeast sporulation occurs via budding -- produces blastospores*

Question 39

are pathogenic fungi dependent on us?

Answer 39

nope | they can grow indefinitely as free living saprophytes

Question 40

are parasitic fungi dependent on us?

Answer 40

nope can grow indefinitely upon non living substrates without any need of intervention of a parasitic cycle in humans/ animals

Question 41

heavy v light exposure in fungal infections

Answer 41

heavy exposure- symptoms appear early | light exposure- appearance of symptoms is later , disease is slower and asymptomatic

Question 42

for diagnosis of a fungus which form is best

Answer 42

the saprophytic is better than the parasitic | bc the morphology in culture is better than the morphology of tissue

Question 43

s/s of mycoses

Answer 43

if uncomplicated fever is low and blood counts aren't sufficiently consistent and characteristic to be of diagnostic value

Question 44

most common nervous yeast infection?

Answer 44

cryptococcus