Bacteria and Fungi Flashcards
Coccus
(spherical) – Coccus sp. (in pairs diplococci, chains streptococci, bunches like grapes staphylococci)
Bacillus
(rod-shaped) – Bacillus sp.
Gram+
bacteria have simple cell walls > peptidoglycan (dark purple)
Some gram-positive strains are also resistant
“Super bugs” such as Staphylococcus aureus (ie MRSA)
alcohol rinse does not remove crystal violet
Gram–
bacteria have cell walls < peptidoglycan, but more lipopolysaccarhides (pale red)
More toxic due to the lipopolysaccharides
More protected due to outer lipopolysaccharide layer(lipo is hydrophobic so it will keep stuff out)
More anti-biotic resistant
Many antibiotics disrupt the peptidoglycans in the cell….no peptidoglycans, no disruption!
Very high in peptidoglycan means the antibiotic will disrupt those linkages and easily get through the bacterial cell
Peptidoglycan
Structural carbohydrate composed of sugars cross-linked with short polypeptides
makes up the cell wall of bacteria
Photoheterotroph
Energy source- light
Carbon source- Organic compounds
Types of organisms- Unique to certain aquatic and salt-loving prokaryotes (for example, Rhodobacter, Chloroflexus)
Photoautotroph
Energy source- light
Carbon source- CO2, HCO3−, or related compound
Types of organisms- Photosynthetic prokaryotes (for example, cyanobacteria); plants; certain protists (for example, algae)
Chemoautotroph
Energy source- Inorganic chemicals (such as H2S, NH3, or Fe2+)
Carbon source- CO2, HCO3−, or related compound
Types of organisms- Unique to certain prokaryotes (for example, Sulfolobus)
Chemoheterotroph
Energy source- Organic compounds
Carbon source- Organic compounds
Types of organisms- Many prokaryotes (for example, Clostridium) and protists; fungi; animals; some plants
What are the 3 main shapes that prokaryotes come in?
Coccoid
Bacilli
Spiral – Spirillum sp.
Endospore
are types of resistant cells produced by prokaryotes to survive harsh environments
(Bacterial cell replicates its DNA and surrounds it in a super resistant layer of the endospore wall as soon as chromosome has been released it will lyse the cell and the endospore will exist in the environment by itself and when conditions are favorable again the cell wall around the endospore will break the bacteria will reestablish )
Can survive boiling water (Need extreme heat and pressure to kill)
Can remain dormant for centuries
Taxis
movement towards or away from a stimulus
Probiotic
something we eat to help establish healthy populations of “good” bacteria
Halophile
“salt loving”, live in super haline (salty) places
Thermophile
“heat loving”, thermal vents, geysers, volcanic hot springs (think Yellowstone)
Acidophile
acid loving”, human gut, volcanic features
Methanogen
release methane
Found in marshes, cattle guts (cow farts)
Important decomposers in the environment
Filamentous
i
Septate
divided, allowing large macromolecules to pass between hyphal cells
Coenocytic
(lacking septa/no divisions) with a continuous cytoplasmic mass
Fruiting body
reproductive structure (mushroom we eat)
Haplontic
dominantly haploid stage
Plasmogamy
fusion of cytoplasm’s from parental mycelia)
Heterokaryon
“multiple nuclei”
When the fungus is in the dikaryotic stage, we say it is a heterokaryon since its mycelium contains two genetically different nuclei within its cytoplasm
Dikaryotic
two haploid nuclei from each parent”, a transition stage between haplontic and diplontic where plasmogamy (fusion of cytoplasm’s from parental mycelia) has occurred, but karyogamy (fusion of nuclei, thus completing fertilization) has not
Karyogamy
fusion of nuclei, thus completing fertilization
Zygosporangium
produces the zygote (zygospore)
a sturdy multinucleate structure in which karyogamy and meiosis occur produced by plasmogamy
represents the zygote (2n) stage in the life cycle, it is not a zygote in the usual sense (that is, a cell with one diploid nucleus)
a zygosporangium is a multinucleate structure, first heterokaryotic with many haploid nuclei from the two parents, then with many diploid nuclei after karyogamy.
zygospore
diploid nuclei produced by karogamy in zygomycetes
Ascocarp
the fruiting body of a sac fungus
contain spore forming asci
Ascus
a saclike spore capsule located at the tip of a dikaryotic hypha of a sac of fungi
Ascospores
(sexual spore) are produced in dikaryotic asci contained within ascocarps
Conidoispores
are produced in structures called conidiophores
Basidiocarp
fruiting body of a dikaryotic mycelium of a club fungus
Basidiospore
sexual spore) are produced in dikaryotic basidia contained within basidiocarps
Mycobiont
o
Photobiont
o
Arbuscular mycorrhizal
(endomycorrhizal) -> Have branched hyphae called arbuscules that penetrate plant host cells to exchange nutrient
What are the 2 main types of mycorrhizae?
Ectomycorrhizal fungi form sheaths of hyphae over the surface of a root and typically grow into the extracellular spaces of the root cortex
Arbuscular mycorrhizal fungi (from the Latin arbor, tree) extend branching hyphae through the root cell wall and into tubes formed by invagination (pushing inward) of the root cell plasma membrane
How do fungi reproduce?
Fungi reproduce via spores, which can be produced sexually (meiospores) or asexually (mitospores)
Explain the evidence of shared ancestry between the fungi and nucleariids.
Phylogenetics has suggested fungi originated from a flagellated unicellular aquatic protist ancestor
- Animals, fungi, and protistan relatives form a monophyletic clade called the Opisthokonts (opistho = flagellal position)
- Fungi more related to single-celled protistan relatives (nucleariids) than animals proper
Nucleariids consist of amoebas that feed on algae and bacteria
DNA evidence suggests that animals are more related to another group of protists (choanoflagellates) than to either fungi or nucleariids
We can conclude then that multicellularity evolved independently in animals and fungi
What are the 5 major groups of fungi?
Chytridiomycetes Glomeromycetes Zygomycetes Ascomycetes Basidiomycetes
Chytrids
Phylum: Chytridiomycota (mycota- phylum level)
basal fungi
~1000 species
Found in lakes and soils,
hydrothermal vents
Most are decomposers(pollen grain), but some are pathogenic
Batrachochytrium salamandrivorans attacks amphibians and has decimated their populations )
some chytrids are mutualists (Live in the guts of sheep to help break down plant matter)
All chytrids have flagellated zoospores (spores that move)
Have cells walls of chitin
Zygomycetes
moulds”
~1000 species
Found in soils and air,
Most are fast-growing moulds, microscopic
Rizopus stolonifer is a common bread mould
Hyphae are coenocytic with septa only in reproductive hyphae
Sporangia -> produces spores
Zygosporangia -> produces the zygote (zygospore)
dominant stage; Haploid
Glomeromycetes
“mycorrhizae”
Phylum: Glomeromycota (formerly Zygomycota)
~200 species
Found in soils and air,
Most are arbuscular mycorrhizal
About 80% plants associate with Glomeromycota
Hyphae are coenocytic
Spores look similar to zygospores
Similar life cycle to zygomycota
Molecular evidence however has discerned that the Glomeromycota is its own monophyletic clade
dominant stage: haploid
Ascomycetes
“sac fungi”
Phylum:Ascomycota
~65,000 species
Found in marine, freshwater, and terrestrial habitats
Can be unicellular yeasts, or multi- cellular fungi
Saprotrophs, pathogens, mutualists, mycorrhizal
Fruiting body: ascocarps
Produces ascospores (sexual) in asci (sing. ascus)
Hyphae are septate
Dominant stage; haploid
Basidiomycetes
club fungi”
Phylum: Basidiomycota
~30,000 species
Contain puffballs, “mushrooms”, shelf fungi
Saprotrophs, pathogens (rusts and smuts), mutualists, mycorrhizal
Fruiting body: basidiocarps containing “gills”
Produces basidiospores (sexual) in dikaryotic basidia (sing. basidium) contained on the gills
Hyphae are septate
FYI: When conditions are optimal for reproduction, basidiocarps can establish within hours
dominant stage; dikaryotic
What are the 2 domains of prokaryotes?
Bacteria and Archaea
Where do prokaryotes live?
Tailing ponds from mining
Super salty deserts and lakes (ie Great Salt Lake in Utah)
Under glaciers in the Arctic and Antarctic
Blood falls in Antarctica
Thermophilic bacteria in yellowstone
Thermal vents surrounding volcanic features
Human gut(very acidic!)
metagenomics
Can use metagenomics to identify prokaryotic species in soil and even the human gut (called the microbiome)
The study of metagenomes
What are Common characteristics of prokaryotes?
0.5 - 5μm in size (exception Thiomargarita namibiensis is 750 μm across!)
Unicellular
Lacks membrane-bound organelles (contains a plasmid (contains the DNA) within the nucleoid,)
Come in three main shapes
Have a cell wall of peptidoglycan (bacteria)
Cell wall is surrounded by a capsule or slimy covering
Some prokaryotes also have fimbriae
Prokaryotes can move within the environments
Can use a flagellum
Reproduce via binary fission
What are the cell walls of prokaryotes composed of?
Bacterial cell walls are composed of peptidoglycan(Structural carbohydrate composed of sugars cross-linked with short polypeptides)
• Archaeal cells walls are composed of other complex sugars and proteins but lack peptidoglycan
Capsule
slimy covering surrounding cell wall
Composed of polysaccharides and/ or protein
Allows adherence to substrata or each other within the colony
Protects against desiccation and bacteriophages(viruses)
fimbriae
Hairlike projections to anchor to hosts or substrata(or to each other)
Gram Staining
uses crystal violet dye and iodine, and alcohol rinse, and a final stain of red dye
Describe movement of prokaryotes?
Chemotaxis–>response to a chemical
Positive chemotaxis -> towards a chemical
Negative chemotaxis -> away from a chemical
flagellum
Describe the flagella in prokaryotes?
Much thinner than eukaryotic flagella and not covered with an extension of the plasma membrane
different in their molecular composition and their mechanism of propulsion
Bacteria and archaea flagella differ in protein composition but are similar in size and rotation mechanism,
How did the flagella arise in the 3 domains?
The structure of the flagella across the 3 domains suggest they arose independently -> they are analogous structures!
Describe reproduction in prokaryotes
binary fission
Under optimal conditions can divide every 1-3 hours
They don’t over divide because of space availability competition
Nutrient and space availability (quorum sensing), self-poisoning, competition limits colony cell
Colony of E.coli can divide in 20 mins
They are small, they reproduce by binary fission, and they have short generation times
Obligate aerobes
need O2 for cellular respiration
Obligate anaerobes
are poisoned by O2
Something else sulfate
Acquire energy from fermentation or anaerobic respiration
anaerobic respiration
in organic molecules other than oxygen accept electrons at the downhill end of the electron transport chain
Facultative anaerobes
use O2 when available but will carry out fermentation or anaerobic respiration when oxygen is absent
nitrogen fixation
converting N2 to NH3
some have mutualistic relationships with plants
heterocysts
ii
nucleoid
a non membrane bounded region in a prokaryotic cell where the DNA is concentrated
plasmid
a small circular double stranded DNA molecule
Compare the chromosomes of prokaryotes and eukaryotes
Prokaryotes generally have circular chromosomes whereas eukaryotes have linear chromosome
in prokaryotes the chromosome is associated with many fewer proteins than are the chromosomes of eukaryotes
prokaryotes lack a membrane-bounded nucleus; their chromosome is located in the nucleoid, a region of cytoplasm that is not enclosed by a membrane
In addition to its single chromosome, a typical prokaryotic cell may also have much smaller rings of independently replicating DNA molecules called plasmids
List the diverse nutritional modes of prokaryotes
Prokaryotes have diverse nutritional adaptations allowing them to inhabit diversely harsh environments
Obligate aerobes
Obligate anaerobes
Facultative anaerobes nitrogen fixation -
How does nitrogen fixation happen?
Have specialized cells called heterocysts in photosynthetic prokaryotes to carry out N-fixation
Nitrogen fixers are often poisoned by oxygen so they have to contain the nitrogen fixing enzyme within a special cell the heterocyst and that is a anaerobic environment just within that specialized cell
Allows them to do photosynthesis and nitrogen fixation
microbiome
the community of microorganisms that live in or on the body
Describe the role of the microbiome and what probiotics are?
Diverse nutritional modes allow diverse bacteria to inhabit the human gut (called our microbiome) (if you eat a lot of carbs your microbiome is going to be different from a person who eats a lot of veggies)
Contain ~10 trillion bacteria in our guts
Are mutualists -> break down food that we cannot
We can absorb the nutrients they break down in exchange for our blood cells producing anti-microbial compounds to reduce competition and keep only the “good” bacteria
We consume probiotics to help establish healthy populations of “good” bacteria
Where do archaea live?
Archaea are prokaryotes that inhabit some of the harshest environments (we call these extremophiles) (difference in cell wall composition allow them to do this)
Thermophile will have different cell wall composition then acidophile –species specific
Where do archaea live? What allows them to live where they do?
Archaea are prokaryotes that inhabit some of the harshest environments (we call these extremophiles) (difference in cell wall composition allow them to do this)
Thermophile will have different cell wall composition then acidophile –species specific
Which is the basal group between bacteria archaea and eukaryotes?
Bacteria are basal
archaea are more closely related to domain eukarya than they are bacteria
What are some common characteristics of all fungi?
There are ~ 100,000 species of identified fungi
Could be up to 1.5 million species!
Fungi can be single-celled(yeasts), microscopic(molds), filamentous or macroscopic(mushrooms)
Found in all habitats, both terrestrial and aquatic
Fungi are the nutrient recyclers within the ecosystem, breaking down decaying organic matter
can be saprotrophs (decomposers), parasites, pathogens, mutualists
How do fungi eat?
•Like animals, fungi are heterotrophs
Animals > ingestion
Fungi > absorption
How do they absorb their food?
Secrete hydrolytic enzymes into the environment through threadlike hyphae which breaks down nutrients
Secrete enzymes to penetrate cell walls of host cells, allowing fungi to get nutrients through parasitism and infection
Can break down a variety of compounds, including lignin(wood) and cellulose (which animals cannot digest)
yeasts
Single-celled fungus that reproduces asexually by binary fission or by the pinching of small buds off a parent cell. Some species exhibit cell fusion between different mating types.
The most common fungal body structures…
are multicellular or single cells ( yeasts)
Describe the fungi body
Hyphae (sing. Hypha) - tiny tubular filaments surrounding the plasma membrane (between the cells and substrate absorbing the nutrients, fingers and arms)
Mycelium > a mass of hyphae that maximizes SA:volume ratio(body)
Fruiting body > reproductive structure (mushroom we eat)
Cell walls > composed of chitin (nitrogen containing polysaccharide)
Hyphae
One of many connected filaments that collectively make up the mycelium of a fungus.
Mycelium
The densely branched network of hyphae in a fungus
that infiltrates the material on which the fungus feeds
What are the 2 forms of hyphae?
Septate (divided, allowing large macromolecules to pass between hyphal cells
Coenocytic (lacking septa/no divisions) with a continuous cytoplasmic mass
Mycorrhizae
are specialized fungi that form associations with plants
Many mycorrhizal fungi look like regular “mushrooms”
(Mushroom sitting under the tree that is the fruiting body reproductive structure all of the mycorrhizal part of the fungi is underground)
Ectomycorrhizal
forms sheaths of hyphae around plants roots(form hyphae along outside of plant root, become extension of roots absorbing nutrients in exchange for photosynthates )
Describe the relationship between mycorrhizae and plants
Mycorrhizal mycelia increase the surface area and efficiency of absorbing phosphate ions and other minerals in the soil
• More efficient than plant roots
In exchange, plants provide the fungus organic nutrients
Mutualistic relationship because plant provides fungi with protection
Spores are only ..
diploid or haploid
Are there genders in fungi?
Theres no genders in fungi just + or – strain
Describe the general life cycle of fungi
Sexual reproduction: Plasmogamy (fusion of cytoplasm) (Heterokaryotic stage) Karyogamy (zygote) (diploid) Meiosis(meiospores) (haploid) Germination (haploid) mycelium (haploid)
Asexual: all haploid
spore producing structures make mitospores
germination
mycelium
What are advantages of sexual reproduction in fungi?
The sexual processes of karyogamy and meiosis generate extensive genetic variation, a prerequisite for natural selection
The heterokaryotic condition also offers some of the advantages of diploidy in that one haploid genome may compensate for harmful mutations in the other.
Describe asexual reproduction in fungi
Many fungi reproduce asexually by growing as filamentous fungi that produce (haploid) spores by mitosis; such species are informally called moulds if they form visible mycelia
by growing as single-celled yeasts. Instead of producing spores, asexual reproduction in yeasts occurs by ordinary cell division or by the pinching of small “bud cells” off a parent cell
gametangium
Multicellular plant structure in which gametes are formed. Female gametangia are called archegonia, and male gametangia are called antheridia
describe the life cycle of zygomycetes
- Mycelia one (+)and one (-)
- neighbouring mycelia of different mating types form hyphael extensions (gametangia) and the gametangia encloses several haploid nuclei (some from both mating types)
- Plasmogamy: A zygosporangium forms containing multiple haploid nuclei from both parents HETEROKARYOTIC
- the zygosporangium develops a rough thick cell walled coating that can resist harsh conditions for months
- Karyogamy: (diploid nuclei) when conditions are favourable karyogamy occurs in meiosis
- The zygosporangium germinates into a sporangium on a short stalk (HAPLOID)
- The sporangium disperse genetically diverse haploid spores
- the spores germinate and grow into new mycelia (HAPLOID)
- Mycelia can also reproduce asexually forming sporangia that produce genetically identical haploid spores
Describe the life cycle of Ascomycete
life cycle follows the standard fungal cycle
dominant stage: HAPLOID
Asexual Stage:
• Conidiospores are produced in structures called conidiophores (compare with the sporangia in Zygomycetes)
Sexual Stage:
- conidia of opposite mating type fuse to hyphae
- Plasmogamy: dikaryotic hyphae produce many dikaryotic asci
- Karyogmay:diploid- occurs within each ascus producing a diploid nucleus
- Meiosis:(HAPLoid) each diploid nucleus divides by meiosis yielding 4 haploid nuclei
- each haploid nucleus divides y mitosis making 8 nuclei , cell wall and plasma membrane develop around the nuclei forming ascocarp
- Ascospores are discharged from asci germinating ones give rise to new mycelia
- Ascospores (sexual spore) are produced in dikaryotic asci contained within ascocarps
- Contain 8 ascospores per ascus
- Conidia may be involved in sexual reproduction of a – conidiospore meets up with a + conidiospore
Describe the life cycle of Basidiomycete
life cycle follows the standard fungal cycle
Asexual Stage: none or very rare
• Sexual Stage:
- 2 haploid mycelia of different mating types undergo plasmogamy
- A dikaryotic mycelium forms growing faster than and ultimately crowding out the haploid parental mycelia
- Environmental cues cause the dikaryotic mycelium to form basidiocarps
- the basidiocarp gills are lined with terminal dikaryotic cells called basidia
- Karyogamy in each basidium produces a diploid nucleus which undergo meiosis
- Each diploid nucleus yields 4 haploid nuclei each of which develop into basidospore
- When mature the basidiospores are ejected and dispersed
- In suitable environment the basidiospores germinate and grow into short lived haploid mycelia
Basidiospores (sexual spore) are produced in dikaryotic basidia contained within basidiocarps
• Contain 4 basidiospores per basidium
Saprotrophs
decomposers
Break down wood, leaf litter, organic matter is soil
Really any carbon-containing substrate->even jet fuel!
Provides inorganic nutrients essential for plant growth
mutualists
Endophytic fungi associate with plants
Not limited to roots (compared to mycorrhizae), found in all plant tissues (leaves stems)
Most are ascomycetes
Provide a range of beneficial effects including producing anti-herbivory
toxins, increasing heat/drought/heavy metal tolerance
Animal mutualists
Some occur in the guts of animals (chytrids in sheep)
Ant colonies farming fungi for nutrients (Leaf cutter ants)
Lichens
Symbiotic relationships between an ascomycete (or sometimes a basidiomycete or glomeromycete) fungus and a green alga and/or cyanobacterium
Grow on various substrata: rocks, soil, trees, metal, concrete, plant leaves
Most are terrestrial but some are aquatic
~13,000 species of lichens identified to date
growth forms:
fruticose(shrubs), foliose(leaf like broad lobes), crustose (super small foliose)
Describe Reproduction in lichens
Sexual via fungal life cycle (ascomycete fungus it’ll produce asci and ascospores germinate release into environment
Asexual via soredia, fragmentation, other specialized structures (fungus plus algae in same blob and when they disperse if they find a favorable habitat they have both partners together and need to just grow on lichen)
