eukaryotic microbes - growth, reproduction and growth requirements

Question 1

fungal classifications

Answer 1

1. Oomycetes > have motile stages and are aquatic fungi
2. Zygomycetes > bread moulds
3. Ascomycetes > yeasts, mildews, aspergillus
4. Basidiomycetes > higher fungi - mushrooms and puffballs
5. Deutromycetes or fungi imperfecti > types of moulds that lack a known sexual cycle.

Question 2

nuclear states of fungi

Answer 2

multicellular fungi can be found in a number of nuclear states.
the number of nuclei and the degree of replication of the nucleus (haploid/diploid) can vary, this is mainly due to the fungus life cycle.
in multicellular fungi with Coenocytic (aseptate) hyphae the organisms is multinucleate. the nuclei of multicellular fungi are usually haploid (single set of chromosomes)
in the karyogamy stage of secual multicellular fungal reproduction, the nuclei fuse to form a zygote and are diploid.

Question 3

yeast reproduction

Answer 3

unicellular fungi can reproduce sexually or asexually depending upon whether conditions are favourable.
asexual reproduction > budding
sexual reproduction > spore formation - spores are retained inside the cytoplasm.

Question 4

what is budding?

Answer 4

in the budding process the yeast cell uses its bud scar.
budding is asymmetric (the two yeast cells produced are not identical in size)
the parent yeast cell develops the bud until it is large enough to be a bulge, that bulge then grows into the daugther cell.
the nucleus migrates and splits, the bud then separates and the daughter cell formation is complete.

Question 5

pseudohyphae

Answer 5

sometimes during the budding process the short chain formed may stick together forming pseudohyphae.
e.g. candida albicans.

Question 6

multicellular fungi dimorphism

Answer 6

multicellular fungi can have one or more appearances in their life cycle, this means they can appear and live as unicellular yeasts or as multicellular fungi.
these types of fungi are called dimorphic fungi, because the process is called dimorphism.
dimorphism usually occurs in response to a change in environment, e.g. temperature. some multicellular fungi do this if they are pathogenic and wish to invade and cause infection. e.g. histoplasma capstulatum.

Question 7

multicellular fungi reproduction

Answer 7

multicellular fungi can reproduce sexually or asexually depending upon whether conditions are favourable.
asexual > produce asexual spores
sexual > hyphae join and share DNA ( genetic information)

Question 8

multicellular fungi asexual reproduction

Answer 8

when conditions are favourable, multicellular fungi produce spores and carry out asexual reproduction.
the spores will grow into fungi that are identical to the parents via mitosis.

Question 9

vegetative hyphae

Answer 9

obtains nutrients from the environment.

Question 10

reproductive hyphae

Answer 10

contain the fruiting body and are where the spores are formed.

Question 11

what are spores?

Answer 11

spores are lightweight, tiny spherical cells (unicellular) that are able to grow into a new organism.
spores are formed in the sporangium on the reproductive hyphae.

Question 12

what is the mature sporangium?

Answer 12

an enclosure where all the spores are kept.