Fungi Flashcards
define polyphyletic
individuals which share characteristics rather than a common ancestor
what were the origins of fungi
based on fossil evidence fungi appeared in the pre-cambrian era around 1 billion years ago
what are some of the defining characteristics of fungi
- eukaryotic = mem bound organelles and nucleus
- haploid genome
- produce spores allowing sexual and asexual reproduction
what is meant by a haploid genome
only contains a single set of chromosomes
what is the fungi cell wall comprised of
chitin and glucans which protect the cell from desiccation and predators
what mode of nutirtion are fungi
heterotrophic- depend on preformed organic nutrients
they absorb soluable nutrients through the cell wall and plasma membrane
what is the network of branches produced by fungi called
the mycelium
how do fungi grow
- they have a vegetive body which is uni or multicellular which produce a thallus
- they will display two morphological stages = vegetative and reproductive
what is the vegetive stage of fungi reproduction
consists of the production of thread like hyphae forming mycelia
the hyphae have tubular structures which can be divided by cross walls called septa
what do perforations in the septa allow
for nutrients to move from cell to cell along the hypha
what is are the different pores found in septa
1) ascomycetes = simple pore with woronin bodies
2) basidomycetes = dolipore
what do woronin bodies do
they plug septal pores after hyphal wounding restricting loss of cytoplasm and site of the injury
what does a parenthesome do
allows for cytoplasmic continunity but blocks movement of large organelles
outline how fungi taken in food
1) exosomes are transported out the hyphae where they process nutrients in the enviro
2) small molecules produced by external digestion are absorbed through the mycelium
what is the special structure called the appressoria
swelling at the end of a spore or hayphae which is used to penetarte host tissue
what is the structure haustoria
produced from spores which germinate on the surface of plants and penetarte tissues of host releasing digestive enzymes
what are rhizomorphs
an aggregation of toughened mycelia which conduct nutrients over long distances
what are chlamydospores
spores conatined within hyphae rounded with a thick cell wall and is a survival structure rich in food reserves
what are sclerotia
a resting body of certain fungi consting of a mass or hyphal threads
what is the difference between biotrophic and nectrophic
bio- feeding with out killing
nec- aggressive and kills the host buy toxins or enzymes
what are mcorrhiza
associatins between fungi and roots
what are the different ways fungi produce asexually
1) fragmentation = fragments grow new colonies
2) budding - somatic cells in yest form buds
3) spores
what are the key steps in sexual reproduction in fungi
1) cell fusion = two different haplodi nuclei exist in same cell
2) nuclear fusion - they fuse forming a diploid zygote nucleus
3) meiosis = meiosis takes place and spores released
