Brooks Biodiversity Unit 2 Exam Study Guide 2024 with complete solution.
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Brooks Biodiversity Unit 2 Exam Study Guide 2024 with complete solution.
The Primary role of Fungi
Decomposers- they break things down
Modes of Nutrition in Fungi
Heterotrophs with extracellular digestion
Exoenzymes
Fungi Release these enzymes outside of the cell wall. Break down complex mo...
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Brooks Biodiversity Unit 2 Exam Study
Guide 2024 with complete solution.
The Primary role of Fungi
Decomposers- they break things down
Modes of Nutrition in Fungi
Heterotrophs with extracellular digestion
Exoenzymes
Fungi Release these enzymes outside of the cell wall. Break down complex molecules
into smaller organic molecules which can be absorbed.
Extracellular Digestion
The release of exoenzymes out side of the cell wall, followed by the absorption of
nutrients..
Saprobes
Fungi that feed on non-living/dead organisms
Symbionts
Fungus that lives with another living organism (form a symbiotic relationship)
Mutualism in Fungi
both organisms benefit, neither is harmed.
Ex: Lichens - fungi and algae (cyanobacteria)
Ex: Mycorrhizae - fungi and plant roots
Commensalism
One organism benefits, the other is unharmed
Parasitism
One organism benefits, the other is harmed
Examples of Parasitism in Fungi
Ex: Fungus as a human parasite (Athelete's Foot)
Ex: Fungus as a plant parasite
1. black stem rust on wheat
2. ergots on rye
3. strawberries with botrytis mold
4. pink ear rot of corn
Black Stem Rust
Parasitic relationship with fungus and plant. Occurs on wheat
Ergots
Parasitic relationship with fungus and plant that occurs on rye and gives hallucinogenic
sensations
Botrytis Mold
Parasitic relationship with fungus and plants that occurs on strawberries
Fungi Characteristics
1. Heterotrophic
2. Extracellular Digestion
3. Chitin-Based Cell wall
4. Most fungi are made up of filaments called Hyphae
,Hyphae
filaments (long and branching) that make up the structure of a fungus
In most fungi, hyphae are the main mode of vegetative growth
Hyphae are Septate or Coenocytic
Yeast
Yeast is a unicellular fungi and do not have/grow hyphae
MOST FUNGI ARE MULTICELLULAR, BUT YEAST IS UNICELLULAR
Septate
You can see the cell separation because the nuclei are confined in and separated by
cell walls
Think "separate"
Coenocytic
You cant see the cell separation. It is multinucleated meaning that there are multiple
nuclei not separated by a cell wall
Thallus/Mycelium
collectively refers to a bunch of hyphae that together make up the body of the fungus
Hyphae (smallest unit) make up the mycelium (entire fungus body)
Haustoria
The hyphal tip of a parasitic fungus that penetrates the cell of other organisms (the host)
After penetration these specialized hyphae release enzymes that break down the cell
wall, thus allowing greater potential movement of organic carbon from host to fungus.
What is Fungi Most closely related to?
Fungi have cell walls and fruiting bodies, so were originally thought to be plants.
However, they are most closely related to animals
Fungi Nuclei
Most fungi cells have 2 nuclei
Mitosis
Has NO prerequisite for cell division, all it needs is a nucleus. What you start with is
what you end with (identical nuclei and identical DNA)
Meiosis
Cell must be a diploid (2n) Process of nuclear division which the ploidy of the parent cell
is halved
3 Types of Meiosis
Zygotic - Phylum Zygomycota
Gametic - Usually in animals
Sporic - Usually in plants
Ploidy
Number of sets of chromosomes present in a nucleus
Haploid - 1 set
Diploid - 2 sets
(Humans have 23 different kinds of chromosomes in each cell and 46 chromosomes in
total)
Syngamy
synthesis of the games
Composed of 2 parts:
1. Plasmogamy
, 2. Karygamy
There are morphological differences between the two individuals (gametes) that engage
in syngamy.
How do fungi reproduce?
Both sexually through meiosis and asexually through mitosis
Asexual Reproduction
Haploid spores produced (n) Spores produced are the same as original fungus because
they are produced through mitosis. Generally occurs when conditions are good because
fungus is well adapted to environment so it can just reproduce itself without needing
modifications to survive.
Sexual Reproduction
Haploid spores produced (n), however spores are different from the original fungus
because they are produced by meiosis. Generally happens with an extreme change in
the environment, which makes sense because it would require genetic variation to
adapt to these new conditions.
What is the benefit of asexual reproduction?
To remove bad genes
What is the benefit of sexual reproduction
To create genetic variation which reduces the possibility of extinction
Are there males and females in fungi?
No. They are known as "+" or "-"
Sexual Dimporhism
Fungi are characterized by Sexual Dimorphisim. Basically, there are morphological
differences between the cells of sexes (males and females) of the same species.
Examples include differences in morphology, size, ornamentation, and behavior.
Heterokaryon
Heterokaryon hyphae produced - have 2 OR MORE nuclei resulting from fusion of
hyphae (n + n)
Dikaryon
Dikaryon hyphae - possess 2 genetically different nuclei in each cell (n + n)
What is the difference between heterokaryon and dikaryon?
The number of nuclei. Heterokaryon can have more than two nuclei, however dikaryon
is precisely two.
Plasmogamy
fusion of the cytoplasm
Plasma membrane of the hyphae fuse
Comes first before dikaryotic stage and karyogamy
Two different n's come together to form n + n
First Part of Syngamy
Dikaryotic Stage
Stage between Plasmogamy and Karyogamy
Plasma membrane and cytoplasm have fused, but nuclei have not joined yet
(n + n)
Karyogamy
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