Presentation on Chemistry of Fungal Cell, Growth of Fungi, and Mode of Nutrition in Fungi.

2. CHEMISTRY OF FUNGI
The chemistry of fungal cell wall contains some useful taxanomic
makers.
Cell wall is also a very important target for anti-fungal agents.

3. FUNGAL CELL STRUCTURE
 Cell wall
 Plasma membrane
 Microtubules
 Nucleus

4.  The fungal cell wall is a complex of chitin. [a polymer
of N-acetylglucosamine] various mannoprotiens together
with α and ß linked 1,3 – D – glucans.
 Electron microscopy of the cell walls of the yeast
Candida albicans shows that they are in layers attached
to plasma membrane.

5.  In most fungal species the inner cell wall consist of a core
of covalently attached branched ß-(1,3) glucan with 3 to 4
% interchain and chitin.
 α(1,3) glucan plays prominent role in the organization of
the cell wall of many human pathogens.
 But this absent in Candida and Saccharomyces cell wall.

6.  The conidial spores and aerial hyphae of mold are often
covered by highly hydrophobic protiens called
hydrophobins that form rodents that protect the spores
from enzymes, oxidants and foreign phagocyts.
 The individual components of cell wall are covalently
cross linked to one another.

7. CELL WALL COMPONENTS
 The major polysaccharides of cell wall matrix consist
of glucans such as manans, chitosan, and galactans.
 Glucans refer to a group of D-glucose polymers
having glycosidic bonds.
 In addition to the chitin, glucan, manan, cell walls
may contain lipid, protien, chitosan, acid phosphate,
amylase, protease, melanin, and inorganic ions
(phosphorus, calcium, and magnesium).

8. PLASMA MEMBRANE
 The main role of plasma membrane include,
• To regulate the uptake and release of materials
 Regulates the passage of materials into and out of
the cell by being selective permeable.
MICROTUBULES
Microtibules are long, hallow cylinders ~ 25 nm in
diameter.
 Involved in the movement of organelles,
chromosomes, nuclei, and golgi vesicles containing cell
wall precusor.

9. NUCLEUS
 The nucleus is bounded by double nuclear
membrane envelope and contains chromatin and a
nucleolous.
 Fungal nuclei are variable in size, shape, and
number.
 The number of chromosomes varies with the
particular fungus.
• S.cerevisiae ; 18 (n)
• T.mentagophytes ; 4 (n).

10. NUTRITION IN FUNGI

11. Nutrition :
 Like animals, fungi are heterotrophs.
 They are use complex organic compounds as a source of
carbon, rather than fix carbon-dioxide from the
atmosphere as do some bacteria and most plants.
 In addition, fungi do not fix nitrogen from atmosphere.

12.  Fungi are mostly saprobes (Saprophyte is an equivalent
term)
 Organism that derive nutrients from decaying organic
matters. They obtain their nutrients from dead or
decomposing organic material derived mainly from plants.
 Fungal exoenzymes are able to breakdown insolube
compounds such as cellulose and lignin of dead wood, into
readily absorbable glucose molecules.

13.  Some fungi are parasitic, infecting either plants or animals.
 Smut and Dutch elm disease affect plants, whereas athlete’s
foot and candidiasis (thrush) are medically important fungal
infections in humans.
 Many parasitic fungi posses haustoria, as these structures
penetrate the tissues of the host, release digestive enzymes
within the host body, and absorb the digested nutrients.

14. FUNGAL GROWTH

15. Growth:
 The vegetative body of a fungus is a unicellular or multi-
cellular thallus.
 Dimorphic fungi can change from the unicellular to multi-
cellular state depending on environmental conditions.
 Unicellular fungi are generally reffered to as Yeasts,
Saccharomyces cerevisiea and Candida species are
example of unicellular fungi.

16.  Most fungi are multi-cellular organisms.
 They display two distinct morphological stages. The
Vegetative and Reproductive.
 The vegetative stage consists of a tangle of a slender thread
like structures called hyphae.
 Whereas the reproductive stage can be more conspicious.
 The mass of hyphae is a mycellium.

17.  It can grow on a surface, in soil or decaying material, in a
liquid or even on living tissue.
 Although individual hyphae must be observed under a
microscope.
 The mycellium of a fungus can be very large.
 Most fungal hyphae are divided into separate cells by end
walls called septa.

18.  In most phyla of fungi, tiny holes in the septa allow for the
rapid flow of nutrients and small molecules from cell to cell
along the hyphae. They arte described as perforated fungi.
 The hyphae in bread molds (which is belong to phylum
zygomycota) are not separated by septa. Instead, they are
formed by large cells containing many nuclei, an arrangement
described as coenocytic hyphae.

19. By Dhaneesh Ram