lecture 3: fungal life cycle + algae

Question 1

spores/sporogenesis/sporophyte

Answer 1

◆ single cells capable of growing into an adult organism
◆ product of meiosis
◆ sporogenesis = the process of spore formation
◆ cells derived from spores produce gametes at some point by mitosis
◆ sporophyte = diploid organism that produces spores by meiosis

Question 2

meiosis/fertilization (general)

Answer 2

meiosis:
◆ production of haploid cells from a diploid cell over two rounds of cell division
◆ in plants – makes haploid spores

fertilization:
◆ union of haploid gametes to produce a diploid zygote
◆ no mitosis after fertilization in fungi

Question 3

gamete/gametogenesis/gametophyte

Answer 3

◆ produced by mitosis
◆ when they come together, they produce a zygote
◆ gametogenesis = the process of gamete formation
◆ gametophyte = haploid organism that produces gametes by mitosis

in fungi:
- no distinct binary “gametes” like egg and sperm cells
- hyphal tips that look the same but express different mating types

Question 4

fruiting body

Answer 4

(in fungi) contain spores which are dispersed for reproduction. ex: mushrooms
◆ basidia lines it
◆ a single mushroom can produce a billion spores

Question 5

basidium/basidiocarp

Answer 5

basidiomycetes = club fungi
basidium = the club-like cell
- best decomposers of wood
- in the basidium, the zygote forms prior to meiosis
- basidia line the gills of the fruiting body (the basidiocarp)

Question 6

fertilization (in fungi): plasmogamy

Answer 6

in fungi: (2-step process)
1) plasmogamy – cytoplasms fuse to become heterokaryon, one mycelium with two distinct haploid nuclei types in each cell or floating around (n+n)

2) karyogamy – the different haploid nuclei sharing the same cytoplasm the fuse to make the diploid zygote

Question 7

mycosis

Answer 7

a fungal infection

• many are plant pathogens