Fungi and Plants Flashcards
Heterotroph
An organism that eats other plants or animals for energy and nutrients. ( animals, most bacteria, fungi)
Autotroph
An organism that produces their own food for energy. Using photosynthesis or chemosynthesis. ( plants, some bacteria, algae)
Structure of Fungi
- It is a heterotroph
- Single celled or made of filaments.
- Cell walls (like plants) but contain more chitin ( like animals)
- No complex transport systems
Chitin
- The most abundant aminopolysaccharide polymer occurring in nature.
- It is the building material that gives energy to the cell walls of fungi.
Single- celled species
Occur in several taxonomic groups ( not monophyletic)
Yeasts
Unicellular Fungi
( Ascomycota and Basidiomycota)
How to tell the difference between Yeast and Bacteria?
- Bacteria are prokaryotes ( no membrane bound nucleus)
- Fungi are eukaryotes ( membrane bound nucleus)
Mycelia
- Mycelium is made of hyphae; thin, long filaments ( high surface area)
- Can pack together to form mushrooms
Hyphae
Usually separated by cross-cells ( septa), it has large pores that allow passage to nutrients, even nuclei.
Thin hyphae —–> Master absorbers
Algae nutrition
Absorb food directly from surroundings ( heterotroph)
- Plants photosynthesize ( autotroph)
- Fungi secrete digestive enzyme externally:
- Saprophytes ( eat dead stuff)
- Symbients ( get fed by others, not always intentional)
- Fungal nutrition has had huge ecological and evolutionary impacts
Impact of fungi nutrition
- Plant lignin and Cellulose are the most abundant molecules on earth.
- Fungi is the first and most efficient decomposer on lignin.
- It is one of very few organisms that can breakdown cellulose.
Lichens
- Symbiosis: Fungi + Algae or Cyanobacteria
- 6% of the earth’s surface ( deserts, Tundra, Forests)
- Important in succession
Myccorrhizae
Plant fungal symbiosis:
- 80% of vascular plants partner with fungi to get nutrients from the soil
- Hyphae massively increase the are of root system for absorption
- important for plant productivity and health
Reproduction
- Many species reproduce in multiple ways, sometimes during both haploid (1n) and diploid (2n) phases:
- Asexual
- Sexual
- Diverse
Haploid (1n)
Single set of chromosomes in an organisms cells.
EGG AND SPERM
Diploid (2n)
Sexually reproducing organisms ( 2 sets of chromosomes)
- Asexual
Fragmentation during haploid (1n) phase of vegetative spores.
- Sexual
- Compatible individuals (1n) fuse their mycelia, to initiate sexual cycle (plasmogamy)
- Ascomycetes and Basidiomycetes
- Dispersal
Fungi move between habitats by dispersing small spores through the atmosphere.
Spores:
- are tough and specialized for dispersal
- unlike hyphae they tolerate dry conditions
- some have ejection mechanisms ( puffballs)
- some use animal dispersers ( stick horns)
Monophyletic Group
evolved from common ancestor and includes all descendants of that common ancestor
Sister Groups
Two groups that split from common node
sharing a node means evolved from common ancestor
Archaeplastids
Plantae and are photosynthesizers (not monophyletic)
Photosynthesis
- Process that converts light energy into chemical energy
- Fixes carbon into organic form
- Produces oxygen
Origin of photosynthesis
- Both photosystems evolved in bacteria
- All photosynthetic eukaryotes use chloroplasts for photosynthesis
The capture of photosynthesis
- Endosymbiotic origin of chloroplasts ( membrane bound organelle site of photosynthesis)
- Eukaryotic chloroplast originated when eukaryote cell engulfed a cyanobacteria.
Endosymbiotic origin of Chloroplasts
Similar to cyanobacteria and behave somewhat independently of cell:
- replicate by fission, independently of cell division
- manufacture their own proteins (autotroph)
- have their own DNA, organized into circular molecules very similar to those in cyanobacteria.
-peptidoglycan is cell of some chloroplasts
–> chloroplasts have at least a double membrane
–> Endosymbiotic cyanobacteria live in cells of some eukaryotes and animals
peptidoglycan
Peptidoglycan is a rigid envelope surrounding the cytoplasmic membrane of most bacterial species
The capture and spread of photosynthesis
- Endosymbiosis leading to chloroplasts first occurred in common ancestor plantae ( primary endosymbiosis)
- Other groups acquired chloroplasts via secondary endosymbiosis
Phytoplankton
- Single celled, free living photosynthetic organisms
- 50% of global photosynthesis
Photosynthetic Bacteria
Responsible for half of the oceans primary productivity
Primary endosymbiosis
2 membranes
archaeplastids
Secondary endosymbiosis
more than 2 membranes
Viridiplantae
- green plants
- monophyletic group
- including green algae and land plants
Non vascular plants
Bryophytes/ earliest branching of land plants/ most ancient
vascular plants
tracheophytes/ vascular tissue only evolved once
Angiosperms
flowering plants
seed plants
- angiosperms and gymnosperms
- monophyletic
- the seed evolved once
Ancestors of the first land plants
= BRYOPHYTES
- no vascular tissue
- no true roots
- absorb nutrients and water through their leaves
- no stomata
stomata
Epidermal cell
regulate gas exchange between the plant and environment and control water loss by changing the size of stomata pore
Mitosis
one cell division
creates 2 identical daughter
meiosis
2 divisions
4 cells with half the genetic material
Bryophytes: reproduction
- Gametophyte phase dominant:
—> unisexual ( each gametophyte is either male or female)
—-> bisexual ( each gametophyte can prduce both female and male)
- need water for reproduction
sphagnum moss
a genus of moss
desiccation
removal or loss of moisture
