Microbes Flashcards
1
Q
What part of the compound light microscope will determine how expensive the microscope will be?
A
condenser units
2
Q
What is refraction?
A
When light crosses through a medium with a different density, its speed changes. Consequently, its path changes. This change in direction is called refraction
3
Q
What is the refraction index a measure of?
A
The refraction index is a measure of how much a medium slows the velocity of light
4
Q
What are normals?
A
There are the normals which are lines perpendicular to the surface. As light moves from air to water, light will bend closer to the normal because it has a higher refractive index.
5
Q
True or false: Higher refractive index = light bends closer to the normal, and lower refractive index = light bends away from the normal.
A
TRUE
6
Q
What is the refractive index of air?
A
1
7
Q
What is the refractive index of glass?
A
1.52
8
Q
What is the refractive index of oil?
A
1.52
9
Q
What are the 3 different types of lenses in a microscope?
A
- Condenser Lens
- Objective Lens
- Ocular lens
10
Q
Why do we use small lenses instead of larger ones?
A
Any aberrations or distortions in the lens will change how the light refracts so we use multiple small lenses instead of one big lens
11
Q
How do you get the total mag?
A
Multiply the mag of both the objective and ocular lenses
12
Q
How did the compound microscope get its name?
A
The objective and ocular lenses magnify the image and to get the total magnification you get the product of both. Hence, why we call it the compound microscope
13
Q
What does the condenser lens do?
A
The condenser lens converges rays of light to a focal point (F) striking the specimen slide on the stage. The height F (the length of the cone of light) can be adjusted by moving the condenser adjustment knob up and down
14
Q
What knob is only used during Koehler illumination and shouldn’t be touched otherwise?
A
condenser adjustment knob
15
Q
What is the focal length?
A
The focal length (f) is the distance of the condenser lens to the focal point (F)
16
Q
What is the working distance>
A
The working distance is the distance between the objective lens and the specimen
17
Q
What are the 4 types of objective lenses?
A
- Scanning objective lens (4X)
- Low-power objective lens (10X)
- High-power objective lens (40X)
- Oil immersion lens (100X)
18
Q
What is N.A and what does this value signal?
A
numerical aperture: This value signals the resolving power of each lens = nsinΘ
19
Q
What is resolution?
A
the ability of a lens to separate or distinguish b/w small objects that are close together: the minimal distance b/w 2 points that can be discerned as 2 entities
20
Q
What is the formula for resolution?
A
d = 0.5λ/nsinΘ
21
Q
What does Koehler illumination protocol ensure?
A
ensures that the cone of light emerging from the condenser lens is centered in your field of view enabling more uniform illumination and minimizing scattering. Consequently, both contrast and resolution improve
22
Q
What happens to light in brightfield microscopy?
A
In brightfield microscopy, the specimen blocks the rays of light from entering the objective lens so then we observe the outline of the organisms and its organelles because the light transmits along its edges and cytosol that’s why the organism appears black and the surroundings are white
23
Q
In dark field, what piece has 3 open segments?
A
dark-field stop (or spider light stop)
24
Q
What does the spider stop do?
A
- Only light passing through the 3 open segments of the ring can reach the condenser lenses. This creates a hollow cone of light whose peak (focal point) reaches the specimen slide, thus creating an inverted hollow cone of light that emerges.
- The spider design of the stop forces all the light that’s transmitted through it to escape beyond reach of the objective lens. Only light that is scattered by the specimen is detected. Consequently, the background appears black and the specimen is illuminated
25
What are the 3 main issues with dark-field?
1. it’s hard to see the distinct shape of the organelles and organisms because of the amount of light that’s being scattered,
2. it illuminates dust
3. cooks the specimen quickly
26
What is the upside of dark-field?
it’s well suited for the observation of tiny specimens including viruses, for observing bacterial motility, and it’s useful for detecting syphilis which creates lesions; if you put the blood under dark-field, because of the spiral shape of the bacteria, it’s easily detectable
27
What 2 domains do Prokaryotes span?
Archaea and Bacteria
28
What's specific about archaea compared to bactera?
Have unique rRNA sequence, cell walls, and phospholipids in plasma membrane and we find in extreme envs
29
What 4 roles can prokaryotes play?
1) Mutualists
2) Commensal
3) Parasites
4) Pathogens
30
what is the cell size of prokaryotes?
0.5-5 micrometers
31
Why are all cells small? (2 reasons)
1) volume grows faster than its surface area -> area = r^2 and volume = r^3: surface area limits cell size
2) Limits of diffusion: speed of molecule diffusion is inhibited by thickness of cell barrier and once inside, diffusion time increases with larger cells bc it takes longer to reach the center of the cell
32
Why are prokaryotic cells so much smaller than eukaryotic cells?
Prokaryotic cells lack a well-developed cytoskeleton and without one, these cells can easily lyse (burst open) so to prevent this, the plasma membrane is bounded by a cell wall. This protection came at the cost of size
33
What is the cell wall of bacteria made of?
peptidoglycan, a network of sugar polymers cross-linked by polypeptides
34
What is peptidoglycan porous to?
It’s highly porous to ions and polar molecules.
35
What is the cell wall of archaea made of and what does it allow for?
they have cell walls ornamented with a variety of polysaccharides and protein. Their unique cell wall allows them to survive in extreme environments.
36
What are cell walls made of in plants?
Cellulose
37
What are cell walls in fungi made of?
chitin
38
What allows plant cells to remain large?
Tricks like cytoplasmic streaming in plant cells keeps the cytosol in motion
39
What 2 things do capsules do for the prokaryotes that they cover?
1) allows them to firmly attach to substrates
2) make phagocytosis by macrophages (cells of the immune system of animals) difficult
40
True or false: Those with capsules are smaller than those without?
True: because it acts as another barrier.
41
What 2 things do fimbriae do for some prokaryotes?
1) allow them to stick to their substrate or other individuals in a colony
2) Makes it difficult for things to diffuse through, thus, acting as another barrier
42
What is a biofilm?
A slimy extracellular matrix
43
What is embedded in the biofilm?
many bacterial cells along w/ polysaccharides, proteins, lipids and DNA
44
Why is diffusion more difficult due to the biofilm?
Diffusion is more difficult because molecules will have to diffuse through this liquid
45
What do some prokaryotes have to compensate for their small size and absence of organelles?
some prokaryotes have highly folded plasma membranes (analogous to the endomembrane system of eukaryotic cells).
46
What do these highly folded plasma membrane do for the prokaryotes that have them?
These specialized membranes perform metabolic functions.
47
What are the 2 main groups of bacteria?
Gram + and Gram -
48
What's the difference between gram - and +?
Gram + = thick peptidoglycan on top of plasma membrane
Gram - = thinner peptidoglycan layer sandwiched b/w plasma membrane and outer covering made of lipopolysaccharide and protein membrane
49
Why are gram + bacteria instantly killed by antibiotics like penecillin?
they target the peptidoglycan layer of the cell wall and it effectively shuts down the ability for bacteria to synthesize it by binding to enzymes necessary for synthesis = cells instantly lyse
50
Why are gram - bacteria less sensitive to antibiotics like penecillin?
because the outer membrane is left intact
51
Who developed the gram stain technique and when?
developed by Christian Gram in 1884
52
What does the gram stain technique do?
quickly determines if an unknown bacterium is gram + or -
Gram + stains purple
Gram - stains pink
53
Why are prokaryotes so successful? (2 reasons)
1) their genetic diversity
2) Metabolic diversity
54
What are 3 factors that contribute to the genetic diversity of Prokaryotes?
1) Rapid rates of reproduction
2) Mutation
3) Genetic recombination
55
What occurs when rapid reproduction is coupled with mutation rates?
Mutation rates during binary fission are low, but bc of rapid reproduction, mutations accumulate rapidly in a population = rapid evolution
56
What are the 3 forms of genetic recombination for bacteria?
1) Transformation: using cell surface proteins to pick up foreign DNA from the surrounding environment
2) Transduction: the movement of genes b/w a bacterium and a bacteriophage
3) Conjugation: F plasmids allow bacteria to produce a sex pilus and transfer its plasmid to another cell
57
What are plasmids?
circular pieces of DNA separate from the nucleoid region that can confer advantages to their host
58
What are 8 characteristics of plasmids?
1) Small
2) Double stranded
3) Containing few genes (<30)
4) independent of nucleoid region
5) can replicate autonomously
6) can integrate into host chromosomes
7) are inherited during cell division but not always equally
8) can confer many advantages to host such as antibiotic resistance from R plasmid
59
what do F plasmids do?
capacity to produce sex pili for conjugation
60
What do R plasmids do?
resistance to antibiotics
61
What do Virulence plasmids do?
make bacterial host more pathogenic
62
What do Col plasmids do?
Produce a protein that kills other bacteria
63
what do Metabolic plasmids do?
Carry genes for enzymes that degrade substances (e.g. pesticides)
64
The metabolic diversity of prokaryotes is due to what 2 things?
their metabolic diversity is the outcome of their genetic diversity and transferable metabolic plasmids
65
What 4 things does metabolic diversity include?
Metabolic diversity includes in: sources of (1) energy, (2) carbon, (3) electron donor, and (4) electron acceptor
66
What is a photoautotroph?
Energy source = light
Carbon source = CO2 or HCO3- (inorganic carbon)
67
What are 3 examples of photoautotrophs?
1) Cyanobacteria
2) Many protists
3) Most plants
68
What are chemoautotrophs?
Energy source = inorganic chemicals (H2S, NH3, Fe2+)
Carbon source = CO2 or HCO3- (inorganic carbon)
69
What kinds of organisms are chemoautotrophs?
Unique to prokaryotes. found in extreme habitats (deep-sea vents). considered one of the oldest on Earth
70
What are photohetertrophs?
Energy source = light
Carbon source = organic compounds
71
What organisms are photoheterotrophs?
Unique to prokaryotes
72
What are chemoheterotrophs?
Energy source = organic compounds
Carbon source = organic compounds
73
What organisms are chemoheterotrophs?
Many prokaryotes, but also many protists, all fungi, all animals and few plants
74
Which 2 Modes of obtaining nutrients is unique to prokaryotes?
1) photoheterotrophs
2) chemoautotrophs
75
True or false: Prokaryotes can also use almost any compound with high potential energy as an electron donor and almost any compound with low potential energy (biding electrons tightly) as an electron acceptor to generate ATP
TRUE
76
True or false: Prokaryotes can't metabolize nitrogen in a variety of ways
FALSE: Prokaryotes CAN also metabolize nitrogen in a variety of ways; fixed N can be used as a donor or acceptor of electrons
77
What are obligate Aerobes?
Require O2 for cellular respiration
78
What are obligate Anaerobes?
Poisoned by O2 and use fermentation or anaerobic respiration
79
What are Facultative anaerobes?
can survive with or without O2
80
What does metabolic cooperation allow prokaryotes to do?
allows prokaryotes to use environmental resources they could otherwise not use as individual cells
81
When can metabolic cooperation occur?
can occur b/w different species or b/w cells of a single individual.
82
What is a biofilm?
a tangled web of polysaccharide fibers that adhere firmly onto substrates. Prokaryotic cells belonging to several different species and genera can cohabitate on surface-coating colonies called biofilms
83
In the cyanobacterium Anabaena, what is the name of photosynthetic cells and N-fixing cells?
Heterocysts
84
In In the cyanobacterium Anabaena, photosynthetic cells and N-fixing cells called heterocysts do what?
exchange metabolic products
85
What group of bacteria can form endospores?
Certain Gram + genera
86
True or false: endospores can remain viable in harsh conditions for thousands of years and they are inert and heat resistant
TRUE
87
What group of bacteria is Clostridium botulinum?
Gram + obligate anaerobe
88
Where are Clostridium botulinum endospores found that could be dangerous for children?
Could be endospores in unpasteurized honey, but will pass through our stomach and will be destroyed. But that’s why in children with less acidic guts, the endospores will grow and can harm/kill the child.
89
How can Clostridium botulinum endospores be killed?
with heat, pressure, or acidity
90
What happens if Clostridium botulinum endospores don't die and they remain in the jar of honey?
if they don’t die from this process, the endospores will begin to grow because they’re in a sealed jar with no oxygen.
91
What is Protobacteria?
largest most diverse group of bacteria
92
What is a subgroup of the protobacteria?
The alpha-proteobacteria include many species that are closely associated w/ eukaryotic ghosts
93
What is an example of an alpha-proteobacteria and why are they closely associated w/ eukaryotic ghosts?
Rhizobium bacteria in the root nodules of leguminous plants. It’s hypothesized that the mitochondrion evolved from the anaerobic alpha-proteobacterium through endosymbiosis (the alpha-proteobacterium was engulfed by an archaeon)
94
What is an informal way to classify protists?
may be grouped by mode of nutrition
95
What are the 3 categories of protists based on modes of nutrition?
1) Photoautotrophic protists = algae
2) Heterotrophic protists = protozoan
3) Mixotrophs: protists that switch between photoautotrophic and heterotrophic nutrition
96
What are the 3 sub-categories of heterotrophic protists?
1) Phagotrophs: phagocytize prokaryotes or other protists
2) Parasites: feed of the cells of hosts
3) Saprophytes: absorb nutrients from dead or decaying matter
97
Protists are also informally grouped by means of locomotion; what are these 4 groups?
1) Flagellates
2) Ciliates
3) Amoeboids: lobes that protrude out and move slowly
4) Gliding: cell movement on a surface without the involvement of external appendages
98
True or false: all 3 basic types of sexual reproduction are represented in protists?
TRUE
99
Is the decoupling of sex from reproduction common in protists?
The decoupling of sex from reproduction - is common with protists. This greatly increases their genetic diversity. Conjugation is an example of this.
100
What is the difference between reproduction and sex?
Growth and Reproduction: generate two similar cells from one parent (changing # of individuals)
Sex: changes the nature but not the number of individuals
101
There are 2 major endosymbiotic events that forever changed the course of evolution on our planet, what is the 1st one?
An archean prokaryote lost its cell wall. Its plasma membrane became highly in-folded creating an endomembrane system and closed off the DNA inside a nuclear membrane (i.e. the nucleus). This prokaryote, now an early eukaryote, engulfed a proteobacterium (a gram - bacterium) = endosymbiont/mitochondrion
102
There are 2 major endosymbiotic events that forever changed the course of evolution on our planet, what is the 2nd one?
1-1.5 bya, a heterotrophic eukaryote (already equipped with a mt) engulfed cyanobacteria (another gram - bacteria). Once again, the engulfed organism became an endosymbiont which we now call chloroplast.
103
Out of the 2 endosymbiotic events, which was the key driver for protistan diversity?
Secondary endosymbiotic event
104
What are the 5 supergroups?
1) Excavates
2) SAR
3) Unresolved (we don't discuss this)
4) Archaeplastida
5) Unikonta
105
What 3 different sub-supergroups occurred with the secondary endosymbiotic event of the heterotroph engulfing a red algae?
1) Dinoflagellates
2) Apicomplexans
3) Stramenopiles
106
What 2 different sub-supergroups occurred with the secondary endosymbiotic event of the heterotroph engulfing a green algae?
1) Euglenids
2) Chlorarachniophytes or Turduncken
107
What are the 3 sub-groups within the Excavates Supergroup?
1) Diplomonads
2) Parabasalids
3) Euglenozoans
108
What are 2 characteristics of the Excavates Supergroup?
1) Specialized feeding groove for phagotrophic nutrition
2) Single, pair, or multiple flagella for locomotion
109
Where do diplomonads live?
Inhabit O2 poor envs = all are anaerobic heterotrophs
110
How many nuclei do diplomonads have?
2 equal-sized nuclei
111
Where are the flagella of diplomonads located?
Multiple anterior (front of the cell) flagella
112
Which group of heterotrophs do Diplomonads fall under?
are often parasites
113
What is an example seen in the lab of a diplomonad?
Giardia spp. Inhabit the small intestine and causes diarrhea. It’s also the cause of traveler’s diarrhea.
114
Where do Parabasalids live?
Also inhabit O2 poor environments = all anaerobic heterotrophs
115
True or false: most Parabasalids are parasites?
FALSE: most parabasalids are endosymbionts of animals
116
What is an example of a parabasalid and what does it eat?
Trichonympha campanula secretes cellulase to digest wood and accounts for 50% of the weight of termites
117
What are the 2 groups within the Euglenozoa clade?
kinetoplastids and euglenoids
118
What are 2 distinct features of the Euglenozoa clade?
1) Lost their plastids
2) A single pair of distinct flagella containing a latticework of proteins that allow it to whip around and propel the organism forward
119
What are 3 characteristics of kinetoplasts?
1) have a single large mt containing many circular DNA molecules
2) Some are planktonic while others survive as parasites
3) Have single flagella
120
What are 4 characteristics of Euglenids?
1) one or more flagella emerging from excavating groove at the anterior of the cell
2) have multiple chloroplasts
3) whip-like flagella and pellicle to provide strength and move through water which is viscous to them
4) Eye spot allows them to detect the wavelength of light
121
What is an example of a kinetoplast that we saw in the lab?
Trypanosoma is a parasite which causes sleeping sickness in humans; go undetected by the host's immune system because of their ability to dynamically change their surface proteins.
122
How do Euglenids have chloroplasts?
Euglenids retained the plastid from the secondary endosymbiotic event involving the engulfing of a green algae = same chloroplast as green or red algae
123
What characteristic makes it so that Euglenids are mixotrophs?
Equipped with chloroplast allows them to be autotrophic and feeding groove for heterotrophic (phagotrophic)
124
What is a proteinaceous strip in euglenids, what does it consist of and what does it allow for?
Pellicle that consists of microtubules that provide strength and flexibility. Allows them to have slug-like mobility in soil or very viscous media
125
Why should we cultivate an interest in protists?
Many protozoans are parasites which infect many people often resulting in debilitating consequences
126
What 3 major clades are included in the SAR supergroup?
1) Stramenopiles
2) Alveolates
3) Rhizarians
127
What is the defining feature of the stramenopiles clade?
Pair of flagella where one is hairy and other isn't
128
What are 3 members of the stramenopiles clade?
1) Diatoms
2) Brown algae
3) oomycetes
129
What are 3 characteristics of Diatoms?
1) Unicellular algae
2) Unique 2 part glass-like walls called frustules made of silicon dioxide embedded in an organic matrix
3) Mostly non-motile, but some species secrete a mucilage from the raphe allowing for gliding motion
130
The morphology of what characteristic in diatoms helps us identify them?
The morphology of frustules: glass-like walls made of silicon dioxide embedded in organic matrix
131
What are 2 services that diatoms provide ecosystems and humans alike?
1) After a diatom population has bloomed, many dead individuals fall to the ocean floor undecomposed. This keeps the fixed carbon out of the atmosphere.
2) Fossilized diatom walls composed much of the sediments known as diatomaceous earth that have many applications (e.g. found in toothpaste, detergents, soundproofing).
132
What are 4 characteristics brown algae?
1) All Multicellular
2) Mostly marine
3) Combination of a smooth (whiplash-like and short) and tinseled flagella (long and hairy) on zoospore and sperm
4) Alternation of multicellular generations (diploid and haploid)
133
What are 3 different examples of oomycetes?
1) Water moulds
2) White rusts
3) Downy mildews
134
What nature of oomycetes had them previously classified as fungi?
Hyphal nature, but molecular systematics confirmed that their origin is the stramenopiles clade
135
What are the cell walls of oomycetes reinforced with?
cellulose
136
What are the 2 heterotrophic modes of oomycetes?
1) parasites
2) saprophytes
137
What is a key feature of the alveolates?
its members includes an air pocket(s) resembling alveoli just beneath the plasma membrane
138
What 3 groups are within the alveolates clade?
1) Dinoflagellates
2) Apicomplexans
3) Ciliates
139
What are 4 characteristics of dinoflagellates?
1) 2 flagella located inside of grooves: transverse and longitudinal
2) Alignment of flagella = spin while move forward
3) Cell membrane reinforced with armour before as symbionts inside animals (corals)
4) diatoms and dinoflagellates = important autotrophic plankton
140
What type of heterotroph as apicomplexans?
parasites of animals, and some cause serious human diseases
141
What is the key feature of apicomplexans?
On one end, the apex, contains a complex of organelles specialized for penetrating (drilling) host cells and tissues
142
What is an example of the apicomplexan which causes malaria?
Plasmodium
143
What is another example of a apicomplexan that is a cat parasite which causes toxoplasmosis in humans?
Toxoplasma
144
What are 6 characteristics of ciliates?
1) lost their red algae symbiont = all heterotrophs specifically phagotrophs
2) cilia covering entire surface
3) below plasma membrane = regular appearance of alveoli
4) have a large macronuclei and a small micronuclei
5) Sex uncoupled from reproduction - during conjugation, 2 individuals exchange haploid micronuclei
6) Contractile vacuoles seen in paramecium expel excess water in an effort to osmoregulate.
145
What's the difference between the nappearance of contractile vacuoles and food vacuoles in ciliates?
Contractile vacuoles appear clear with a star-like pattern unlike food vacuoles that are grainy and more circular
146
What are 2 defining features of all Rhizarians?
1) long thin pseudopods
2) calcareous shells
147
What is the mode of nutrition of almost all Rhizarians?
Heterotrophic
148
What are the 3 groups within the Rhizarian clade?
1) Forams
2) Cerozoans
3) Radiolarians
149
What were forams named after?
named for their porous, generally multi-chambered shells called tests
150
What are 5 characteristics of Forams?
1) Tests (porous, chambered shells)
2) Pseudopodia extend through pores in the test = movement + feeding (phagotrophs)
3) Many habour algal endosymbionts
4) sensitive to temp
5) coiling direction of some species dependent on temp
151
What group within the Rhizarian clade are sensitive to temp therefore presence or absence on the ocean floor give us clues to the past?
Forams
152
Which Pleistocene species of forams coils to the right in water temps greater than 10C and left in less than 8-10C?
Globorotalia truncatulinoides
153
What are 3 characteristics of Cerozoans?
1) most are heterotrophic, but 1 group retained plastid = autotrophic
2) Autotrophic clade = includes chlorarachniophytes (turduckens)
3) descendent from a secondary endosymbiotic event involving a green algae
154
What are 3 characteristics of Radiolarians?
1) Pseudopodia radiate from central body and surrounded by thin layer of cytoplasm
2) Pseudopods engulf food = phagotrophs
3) Cytoplasmic streaming brings food to main part of cell
155
What are the 2 clades included in the Archaeplastida supergroup?
1) Red algae clade
2) Green algae clade
156
What gave rise to red and green algae protists in the archaeplastida supergroup?
Roughly 2 bya, in a primary endosymbiotic event, a heterotrophic protist phagocytized a cyanobacterium
157
What are 2 characteristics of red algae clade?
1) includes large multicellular protists
2) harness the shortest wavelengths of visible light (blue and green) that reach deeper in water to photosynthesize
158
What is the pigment used by red algae which is responsible for absorbing blue and green light?
phycoerythrin
159
What 2 protistan clades are included in the green algae clade?
1) Charophytes
2) Chlorophytes
160
What 2 traits do charophytes share with plants?
1) Cellulose-synthesizing protein rings embedded in plasma membrane of cells
2) Phragmoplast that helps establish a new cell after cell division
161
What is an example of a charophyte seen in the lab?
Spirogyra (have pyrenoid bodies)
162
True or false: Chlorophytes are solely colonial?
FALSE: range from unicellular (Chlamydomonas) to colonial (Volvox)
163
What's a distinct feature of Chlorophytes?
Pyrenoid bodies within chloroplasts which function to reduce rates of photorespiration
164
What % of global carbon fixed is due to Pyrenoid bodies?
Nearly 30%
165
What 2 clades are within Unikonts?
1) Amoebozoans
2) Opisthokonts include animals, fungi and 2 protistan clades (nucleariids and choanoflagellates)
166
What 4 groups are included in the amoebozoans clade?
1) Plasmodial Slime Moulds
2) Cellular slime moulds
3) Tubulinids
4) Entamoebas
167
What are 4 characteristics of plasmodial slime moulds?
1) one stage of life cycle = diploid nucleus in sinfle cell divides mitotically to form large multinucleated cell
2) This mass extends pseudopodia through decomposing food (phagocytosis)
3) mass becomes weblike producing fruiting bodies called sporangia within which meiosis occurs and haploid spores are discharged
4) haploid spores produce amoeboid or flagellated cells that fuse together to restore the diploid state
168
What are 3 characteristics of cellular slime moulds?
1) composed of haploid solitary cells with amoeboid movements
2) solitary cells aggregate together to form what looks like a multicellular body when food depleted
3) Fruiting bodies emerge up from the cell aggregate and spores are released in hopes of finding new sources of food
169
What are 4 characteristics of Tubulinids?
1) Have lobe- or tube-shaped pseudopodia
2) They're common unicellular protists in soil, freshwater and marine environments
3) Heterotrophs looking to phagocytize bacteria + protists
4) Found in ventilation ducts (found in areas of moisture and constant supply of microbial food) feeding on microbial biofilms
170
What are 3 characteristics of Entamoebas?
1) parasites of vertebrates and some invertebrates
2) have a single bulging pseudopod
3) secrete enzymes that degrade human epithelial cells on which they feed
171
What unicellular protistan clade in the Unikonts supergroup are fungi most closely related to?
Nucleariids
172
What is the defining feature of opisthokonts?
posterior flagellum used for forward propulsion (flagella in all other eukaryotic supergroups is anterior facing like euglena)
173
What are the 5 phyla within the fungi kingdom?
1) Chytrids
2) Zygomycetes
3) Glomeromycetes
4) Acomycetes
5) Basidiomycetes
174
Why is it that of 100,000 described fungal species, 65% of them are ascomycetes and basidiomycetes?
These phyla are often large and colourful. In other words, easily observed and characterized
175
What are the 2 traits shared by all members of the fungi kingdom?
1) All heterotrophs that absorb nutrients from outside of their bodies
2) Use enzymes to break down a large variety of complex molecules into smaller organic compounds
176
Which of the 2 main traits of fungi contributes to their ecological success?
The versatility and wide variety of the enzymes used to break down many different types of complex molecules
177
What is a service that the fungi kingdom can provide using their enzymes that break down complex molecules?
Bioremediation
178
What are the 3 roles that fungi can play?
1) Decomposers
2) Mutualists
3) Parasites - some are pathogenic
179
What are cells walls of fungi made of?
Chitin
180
What is chitin?
A modified polysaccharide that contains nitrogen
181
Fungi are mostly multicellular, but single-celled species are also represented. What are the 2 groups that are single-celled?
1) Yeasts
2) Chytrids
182
What are multicellular fungi composed of?
hyphae (thin filaments) tangled together into a dense mycelium (a network of hyphae)
183
Are mycelium of fungi generally haploid?
Yes, generally haploid, but not always
184
What are fungi that are morphologically limited to just hyphal growth forms called?
Moulds = fungus that don't produce fruiting body (mushroom)
185
The fungi that do produce macroscopic fruiting bodies (ascomycetes and basidiomycetes) are named base on what?
These fungi are named based on their distinct fruiting bodies: cup fungi, shelf fungi, puff balls, etc.
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What is the structure of septate hyphae?
Hyphae divided into cells called septa, with pores allowing cell-to-cell movement of organelles
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Which types of fungi have septate hyphae?
Fungi with septate hyphae have greater structural integrity. Hence why they can grow elaborate fruiting bodies (e.g. mushrooms).
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What is the structure of coenocytic hyphae?
lack septa and have a continuous cytoplasmic mass with hundreds or thousand of nuclei = moulds
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What are haustoria and what do they allow for?
Specialized hyphae that allow them to penetrate tissues and cells of their host and increase their exchange. These fungi can be mutualists, parasites, or pathogens
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which stage during the fungal life cycle provides an opportunity for genetic recombination?
Heterokaryotic stage
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How many opportunities does the fungal life cycle offer for spore dispersal?
at least 2 opportunities
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What is plasmogamy?
union of 2 mycelia of opposite mating types; fusion of cytoplasm
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What is the heterokaryotic stage?
Stage following plasmogamy were the haploid nuclei from each parent do not fuse right away; they coexist in the mycelium (N + N)
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What is karyogamy?
nuclear fusion of haploid nuclei which could occur hours, days or even centuries later
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What is produced during karyogamy?
diploid cells
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What occurs during the diploid phase of fungi?
short-lived and undergoes meiosis, producing spores which are haploid and they will land somewhere to create a new hyphal network
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What is the defining feature of Chytrids?
retention of the posterior flagellum = characteristic of opisthokonts
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Dyuring what parts of the life cycle of chytrids is their posterior flagellum observed?
gametes and spores (zoospores)
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What are 4 characteristics of Chytrids?
1) Retention of posterior flagellum
2) Mostly unicellular, but have some filamentous forms
3) Few short filamentous root-like structures rhizoids for anchoring into substrates (living or decaying material)
4) alternation of generations is observed in this phylum
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Since the body of Chytrids don't form elaborate mycelia and instead have rhizoids for anchoring onto substrates, what is the body of chytrids called?
Body of such chytrids is described as a thallus rather than a mycelium
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What does the sporophyte phase of chytrids look like?
Have Zoosporangium (Mitosporangium = 2N) and a Resistant Sporangium (Meiosporangium = 2N) which both release spores
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What does the gametophyte phase of chytrids look like?
Rectangular female gametangium with a more circular male gametangium on top which releases gametes = 1N
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What are the 3 key traits of zygomycetes?
1) Coenocytic moulds
2) Septum develops only to section off the gametangium: hyphae of opposite mating strands produce buds that differentiate into gametangia
3) Sporangiophores: structure with the sporangium and within that are spores (asexual reproduction)
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What is the most elaborate part of the mycelium of zygosporangium?
Sporangiophores
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What are sporangiophores?
erected filaments (hyphae) on which sporangia are borne from zygomycetes. Contained inside the sporangia are thousands of haploid, mitotically-derived, spores = asexual reproduction
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Is the asexual or sexual reproduction part of the zygomycetes life cycle the most dominant?
asexual reproduction, is the most dominant in the life cycle of zygomycetes.
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When does sexual reproduction occur in zygomycetes?
Sex occurs when mycelia from 2 opposite mating strands unite
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Describe the sexual reproduction life cycle of zygomycetes?
1) Hyphae of diff mating types produce buds that differentiate into gametangium separated from the rest of the mycelium by a septum
2) gametangia of the two mating strands fuse, in a process called plasmogamy which then differentiates into a resistant and conspicuous structure called a zygosporangium
3) Within the zygosporangium, the nuclei fuse to temporarily restore the diploid condition. This process of nuclei fusion is called karyogamy.
4) Meiosis follows karyogamy. When conditions for dispersal are suitable, a sporangium emerges out of the zygospore and haploid spores are dispersed
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Some zygomycetes, such as the Pilobolus, are capable of doing what with their sporangia?
They can ‘aim’ and shoot their sporangia toward bright light
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What is the ecological role of glomeromyecetes?
Plant mutualist
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Are glomeromycetes exclusively sexual or asexual?
asexual
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What do Glomeromycetes form?
They form arbuscular mycorrhiza and the hyphae (mostly coenocytic) of the members of this phylum produce a haustorium
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What part of the plant does the haustorium push into?
pushes into the plasma membrane of cortical cells in plant roots
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What does this tree-like form of the Glomeromycetes do for the plant
This tree-like form increases the rate of nutrient exchanges with the plant; the plant received mineral nutrients while the fungus laps up fixed carbon
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True or false: Glomeromycetes are only asexual and no macroscopic fruiting body?
TRUE
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What are the 3 distinct features of Ascomycetes?
1) Asci
2) Conidiophores
3) Ascocarps
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Do all members of the ascomycetes phylum produce elaborate fruiting bodies?
NO: The ascomycetes phylum includes fungi that produce elaborate fruiting bodies (e.g. truffles), molds that are restricted to hyphal growth forms (e.g. Penicillium), and single cells (e.g. yeasts)
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What are the 2 defining features of the ascomycetes phylum?
1) Septate hyphae
2) distinct spore producing structures that appear during the sexual and asexual stages of reproduction
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What is sexual reproduction in ascomycetes marked by?
marked by the production of resistant structures called asci (ascus, singular) within which meiosis occurs to produce ascospores
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How are asexual spores in ascomycetes produced?
Spores produced asexually (i.e. mitotically) are called conidia and are borne on specialized hyphal tips called conidiophores
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What are the names of asexual and sexually produced spores of ascomycetes called?
Sexual = ascospores produced in asci
Asexual = Conidia
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Where are condia borne on in ascomycetes>
conidia and are borne on specialized hyphal tips called conidiophores.
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How do single-celled yeasts in the ascomycetes phylum reproduce asexually?
Diploid yeast cells reproduce asexually by binary fission or budding
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What is another name for diploid yeast cells?
vegetative cells
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Describe sexual reproduction in yeast cells?
1) Sometimes yeast cells differentiate into resistant structures called asci (sexual cells) within which the diploid nucleus undergoes meiosis
2) Meiosis produces 4 haploid nuclei within each ascus
3) Following meiosis, one round of mitosis doubles the number of nuclei to 8
4) Once discharged, the haploid spores become haploid yeast cells indistinguishable from the diploid variety. Haploid cells of opposite mating types can fuse to restore the diploid condition.
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How do multicellular ascomycetes reproduce asexually?
Do this by erecting specialized hyphae called conidiophores, from a network of septate haploid hyphae. The terminal cells of the conidiophores differentiate into spores called conidia. If or when the conidia land on a suitable substrate, they will germinate and grow to produce a new mycelium.
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True or false: While most moulds in this phylum are limited to sexual reproduction, the more complex ascomycetes include a asexual stage that leads to the formation of large fruiting bodies.
FALSE: While most moulds in this phylum are limited to asexual reproduction, the more complex ascomycetes include a sexual stage that leads to the formation of large fruiting bodies.
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Describe Sexual reproduction in multicellular ascomycetes?
1) Plasmogamy: cytoplasm of the conidia fuses with that of the cell at the tip of a hypha
2) Containing two haploid nuclei, the terminal hyphal cell is now dikaryotic
3) From this single cell grows an elaborate dikaryotic mycelium where the terminal end cells of some of these filaments will differentiate into asci.
4) Inside each ascus is where karyogamy occurs
5) The short-lived diploid stage is followed by meiosis producing 4 haploid nuclei
6) A single round of mitosis follows to yield 8 ascospores within each ascus. The asci are always densely crowded in an elaborate cup-like structure called an ascocarp which contains dikaryotic hyphae that did not differentiate into asci; these are called sterile paraphyses
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Karyogamy only occurs in what colour of hyphae in ascomycetes?
karyogamy only occurs in the yellow dikaryotic hyphae that emerges from the 2 hyphae of different mating types fusing via plasmogamy
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Where does karyogamy occur in multicellular ascomycetes?
Inside each ascus is where karyogamy occurs
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What does the ascocarp also contain along with ascospores?
The ascocarp also contains dikaryotic hyphae that did not differentiate into asci; these are called sterile paraphyses
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When does the sexual stage begin in multicellular ascomycetes?
The sexual stage begins when a conidium lands on the hypha of an opposite mating type
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What is a distinct feature of ascocarps/ascomycetes?
Diversity in ascocarps
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What are the 3 types of ascocarps?
1) completely closed = cleistothecium
2) narrowly open = perithecium
3) fully open = apothecium
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What is a mutualistic relationship that ascomycetes form?
Ascomycetes also form mutualistic associations with green algae and cyanobacteria = lichen
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In the mutualistic relationships between Ascomycetes, green algae and cyanobacteria, what does each member provide?
The algae provide carbon compounds, cyanobacteria also provide organic nitrogen, and fungi provide the environment for growth
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Can lichens reproduce sexually or asexually or both?
Both
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How do the fungi (most often ascomycetes) of lichens reproduce asexually?
Asexual reproduction is by fragmentation or formation of soredia, small clusters of hyphae with embedded algae
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What is the common name of Basidiomycetes?
club fungi
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What are the 2 ecological roles that Basidiomycetes have?
include important plant mutualists and parasites: the ectomycorrhizae and the rusts and smuts (a group of parasites)
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What does sexual reproduction look like in basidiomycetes?
1) haploid septate hyphae of opposite mating strands fuse together forming a long-lived dikaryotic mycelium
2) Under certain environmental conditions, the mycelium will produce fruiting bodies called basidiocarps
3) The underside of the mushroom basidiocarp is lined with basidia where karyogamy will occur
4) Diploid phase is very short lived and immediately followed by meiosis to yield four basidiospores which rest on top of tiny buds called sterigmata that sit on top of each basidium
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What is the sterigmata in sexual reproduction in basidiomycetes?
Tiny buds where 4 basidiospores rest on top of
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Where does karygomay occur in basidimycetes?
The underside of the mushroom basidiocarp is lined with basidia where karyogamy will occur
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True or false: Basidiomycetes can be pathogens?
TRUE
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What is an example of a pathogenic Basidiomycete?
Puccinia graminis = wheat rust that produces 5 different kinds of spores (!!!) and has two possible hosts -> Infects monocots and dicots
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What phase of all fungi is the shortest and what occurs after?
the shortest phase is the diploid phase and quickly following this is meiosis to produce spores
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What % of known fungal species are parasites or pathogens?
30%
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What % of the world's fruit is lost each year to fungi?
10%-50%
