Fungi Flashcards
Define the term saprophytes?
organisms that obtain organic matter from dead organisms
What is heterotrophic nutrition?
The organism requires organic material from the surrounding environment, it can not produce its own macromolecules
What are fungi?
Fungi are eukaryotic organisms with heterotrophic nutrition (that is, requiring organic material from the environment). They exist as saprophytes
(organisms that obtain organic matter from dead organisms), parasites and commensals.
What are the two main groups of fungi?
Moulds and yeasts
Describe the structural characteristics of fungi?
Rigid cell walls composed of about 80% polysaccharide, 10% protein and 10% lipid.
Also contains Chitin which is a polymer of the polysaccharide NAG which is also found in insect exoskeletons and bacterial cell walls
Also contains mannans and glucans
Fungi have plasma membranes containing characteristic sterols
membrane bound organelles
How do moulds reproduce?
Moulds grow by extension of branched cellular laments called hyphae,
Hyphae have cross-walls or septa or form one
continuous tube.
cross-walls are perforated, allowing continuity of the cytoplasm throughout the hypha.
Hyphae grow by apical extension and form thick networks called mycelia (singular: mycelium).
They reproduce by means of spores, which
can be formed by either asexual cell division or sexual reproduction.
How do yeasts reproduce?
Yeasts reproduce by asexual budding, where a cell develops a protuberance that grows larger and, with its own nucleus, finally separates from the parent cell.
A few yeasts reproduce by a fission process. Some fungi, called dimorphic fungi, are able to grow as either moulds (lamentous growth) or yeasts
(unicellular growth) depending on the growth conditions.
What are dimorphic fungi?
Fungi which are able to ow as either moulds or yeasts depending on the growth conditions
Define biotrophy?
obtaining organic matter from living organisms
This occurs with fungi once they are inside the host.
How do fungi break down their food?
They release enzymes outside of themselves which degrade the organic substrate before absorbing the soluble products
What damage to fungi cause in a human host?
Tissue degradation as a result of the enzymes the release
Can also cause and allergic reaction
What are diseases caused by fungi called?
The diseases caused by fungi are called mycoses.
Where are superficial mycoses found?
Hair, skin, nails and mucous membranes
Usually passed from person to person such as ringworm
Where are subcutaneous mycoses found?
Chased by fungus in the solid which gain access to the skin via wounds, unable to break through the skin without previous injury
Usually contracted from the environment
Where are systemic mycoses found?
These fungal spores are usually inhaled
They are produced by soil fungi.
Usually contracted from the environment
