Fungi Flashcards
prokaryotic
contain no membrane bound nucleus or membrane bound organelle
eukaryotic
contains a membrane bound nucleus and membrane bound organelle
asepsis
excluding pathogens from as much of the environment as possible
sterile
free from all micro organisms
heterotrophic
organisms that are not capable of making their own food
autotrophic
organisms capable of making their own food using energy
saprophytic
organisms that obtain their food from dead organisms
parasitic
two organisms of different species that live together where one benefits and causes harm to the other
obligate parasites
obtain their food from a living host but do not kill them
facultative parasites
obtain their food by killing the host and feeding on the remains
symbiotic
organisms that live in close contact with a second species and at least one organism benefits
mycology
study of fungi
five kingdoms of living things
animalia plantae monera protista fungi
main features of the kingdom of fungi
heterotrophic
eukaryotic
mainly multicellular (excl. yeast)
have cell walls made of chitin
important structures of all fungi
hyphae
mycelium
cell walls made of chitin
chitin
carbohydrate that gives cell wall strength
role of parasites
natural selection
eg athlete’s foot
role of saprophytic organisms
responsible for decomposition
eg mushrooms and mould
examples of fungi
edible eg field mushrooms
poisonous eg death cap, destroying angel
economic importance of fungi
beneficial fungi:
yeast - used to make bread/alcohol
source of food - eg mushrooms
harmful fungi:
infection - eg athlete’s foot
food spoilage - eg Rhizopus on bread
rhizopus reproduction
asexual - by spores
sexual - by hyphae
rhizopus mode of nutrition
saprophytes - feed on bread, veg. peelings
hypha
single threadlike
multinucleate (haploid)
function: digest and absorb substrate
mycelium structure
made up of large numbers of hyphae
rhizoids
provide extra surface area for absorption, digestion of material, anchorage
stolon
aerial hypha that allows rhizopus to spread
conditions that cause rhizopus to produce seuxually
lack of water
unsuitable temperature
sexual reproduction in Rhizopus
- between + and - strain
- swellings form on each hypha (progametangia)
- swellings fuse = gametangia
- walls between gametangia break down, nuclei from each hypha move into swellings and fuse (diploid zygote)
- gametangia develop into zygospore
- zygospore germinates by meiosis to produce a haploid hypha
- sporangium develops at the tip
asexual reproduction in Rhizopus
- hypha develops into sporangiophore
- tip of sporangiophore swells and becomes a sporangium
- inside sporangium: haploid spores produced by meiosis
- dry conditions: sporangium dries out, releases spores, each develop hyphae when on a suitable substrate
economic importance of yeast
used in bread/alcohol production
differences between yeast and rhizopus
yeast:
unicellular
no hyphae
does not produce zygospores
Rhizopus:
multicellular
has hyphae
produces zygospores
asexual reproduction in yeast
budding
- extension develops on cell (bud)
- bud fills with cytoplasm
- nucleus divides by mitosis
- daughter nucleus enters bud
- bud can either:
- separate from parent to become new individual
- not separate, but can itself bud. this is how long colonies of yeast spread
advantages of asexual reproduction in yeast
rapid no variation (mitosis)
disadvantages of asexual reproduction in yeast
increased risk of disease
overcrowding
experiment (before the steps)
nutrient used: agar why: food source which provides a medium for yeast to grow on leaves used: sycamore or ash how was aseptic technique ensured: -wash bench with Milton -sterilise equipment (flame with bunsen) -wash hands with soap -minimal opening of petri dishes
experiment method
- cut and collect leaves
- wash bench
- flame a cork and cut out disks
- flame forceps, allow to cool
- carefully raise the base of the petri dish just enough to work with
- using forceps, smear dots of petroleum jelly onto the inside of the lid. work quickly to avoid micro organisms entering
- use forceps to attach a leaf disc to each blob of jelly
- seal the dish with parafilm to prevent possible contamination
examine presence or absense of colonies after incubation
disposal: place all dishes in an autoclave
control of experiment
sealed petri dish with malt agar and no leaves
show that leaf is the only course of yeast
storage during incubation experiment
store all petri dishes right side up in an incubator at 20ºC for 24 hrs
turn all petri dishes upside down and incubate at 20ºC for 2-7days
results of experiment
pink colonies of yeast will form
control: no change
