Recall from chapter 8
Aerobe:
An organism REQUIRING molecular oxygen (O2) for growth.
Recall from chapter 8
aerobic respiration:
Respiration in which the final electron acceptor in the electron transport chain is molecular oxygen (O2)
Recall from chapter 8
aerotolerant anarobe:
An organism that does NOT use molecular oxygen, but is not affected by its presence.
Recall from chapter 8
anarobe:
An organism that does NOT require molecular oxygen for growth.
Recall from chapter 8
Anaerobic respiration:
Respiration in which the final electron acceptor in the electron transport chain is an INORGANIC MOLECULE other than molecular oxygen (O2); for example, a nitrate ion or CO2.
Recall from chapter 8
Anabolism:
All syntheses reactions in living organism; the building of complex organic molecules from simpler ones
Recall from chapter 8
Catabolism:
All decomposition reactions in a living organism; the breakdown of complex organic compounds into simpler ones.
Recall from chapter 8
Catalase:
An enzyme that breaks down hydrogen peroxide: 2h202-->2h2O+O2
Recall from chapter 8
Catalyst:
A substance that increases the rate of chemical reaction but is not altered itself.
Recall from chapter 8
Chemoautotroph:
An organism that uses an inorganic chemical as an energy source and CO2 as a carbon source.
Recall from chapter 8
Chemoheterotroph:
An orgnanism that uses organic molecules as a source of carbon & energy.
Photoautotroph:
An organism that uses light as its energy source & carbon dioxide (CO2) as its carbon source.
Photoheterotroph:
An organism that uses light as its energy source & an organic carbon source.
Inorganic compound:
A small molecule that does not contain carbon & hydrogen
Organic compound:
A molecule that contains carbon & hydrogen
An organism that uses an inorganic chemical as an energy source and CO2 as a carbon source.
Chemoautotroph:
An orgnanism that uses organic molecules as a source of carbon & energy.
Chemoheterotroph:
Respiration in which the final electron acceptor in the electron transport chain is molecular oxygen (O2)
aerobic respiration:
Respiration in which the final electron acceptor in the electron transport chain is an INORGANIC MOLECULE other than molecular oxygen (O2); for example, a nitrate ion or CO2.
anaerobic respiration:
A small molecule that does not conatin carbon & hydrogen
Inorganic compound:
Arthropods:
are animals twith jointed legs. The arthropods that transmit diseases are important in microbiology. These include ticks & some insects; most often members of the misquito family are responsible for transmitting disease.
Helminth:
are multicellular animals. They are chemoheterotroph. Most obtain nutrients by ingestion through a mouth; some are absorptive. Parasitic heminths often have elaborate life cycles including egg, larva & adult.
Fungi:
are in the Fungi kingdom. Fungi are chemoheterotrophs & acuire food by absorption. W/the exception of yeasts, fungi are multicellular. Most reproduces w/sexual & asexual spores.
Algae:
belong to several kingdoms & can reproduce both sexually & asexually. They are photoautotrophs & produce several different photosynthetic pigments. They obtain nutrients by diffusion. Some are multicellular, forming colonies, filaments, or even tissues. A few produce toxins.
Protozoa:
belong to several kingdoms. Most are chemoheterotrophic, but a few are photoautotrophic. They obtain nutrients by absorption or ingestion. All are unicellular, and many are motile. Parasitic protozoans often form resistant cysts.
Fungi, protozoa, and helminths
cause diseases in humans. Most of these diseases are diagnosed by microscopic examination. Like bacteria, fungi are cultured on labroatory media.
Infections caused by eukaryotes are
difficult to treat because humans have eukaryotic cells.
Algal diseases of humans are
not infectious; they are intoxications because the symptoms are due to ingesting toxins produced by the algae
Arthropods that transmit
are called vectors. Arthropod-brone diseases such as West Nile encephalitis are best controlled by limiting exposure to the arthropod.
Mycorrhizae:
Nearly all plants depend on symbiotic fungi, known as mycorrhizae, which help their roots absorb mineral & water from the soil.
Vegetative Structures:
Fungal colonies are described as vegetative structurs because they are composed of the cells involved in catabolism & growth
Thallus
(body) of a mold or fleshy fungus consists of long filaments of cells joined together; these filaments are called hyphae
Hyphae
long filaments joined together that make up the flshy fungus.
Septa:
cross walls in the hyphae, which divide them into distinct, uninucleate cell-like units.
Septate hypha:
multiple septa in a hypha.
*See picture to the left.
Coenocytic hypha:
Hyphae w/no septa; also called coenocytic hypha
* see visual on the right.
How do Hyphae grow?
By elongating at the tips; each part of a hypha is capable of growth & when a fragment breaks off, it can elongate to form a new hypha.
When fragments of hypha break off what can happen?
It can elongate to form a new hypha
In the laboratory, fungi are usually
grown from fragments obtained from a fungal thallus.
The portion of a hypha that obtains nutrients is call the
vegetative hypha
The portion of a hypha concerned w/reproduction is the
reproductive or aerial hypha, named because it projects above the surface of the medium on which the fungus is growing.
Aerial hyphae
often bear reproductive spores
When conditions are suitable, the hyphae grow to form a filamentous mass called a __________, which is visible to the unaided eye.
mycelium
Yeasts:
Yeasts are nonfilamentous, unicellular fungi that are typically spherical or oval.
Like molds, yeasts are widely...
distributed in nature; they are frequently found as a white powdery coating on fruits & leaves.
Budding yeasts
Such as Saccharomyces, divide unevenly.
In budding
the parent cell forms a protuberance (bud) on its outer surface.
As the bud elongates-
the parent cell's nucleus divides & one nucleus migrates into the bud.
* Cell wall material is then laid down between the bud & parent cell, & the bud eventually breaks away.
One yeast cell can in time produce up to ___ daughter cells by budding.
24
Some yeasts produce buds that fail to detach themselves; these buds form a short chain of cells called a
pseudohypha.
Candida albicans
attaches to human epithelial cells as a yeast but usually requires pseudohyphae to invade deeper tissues.
Fission yeasts
such as Schizosaccharomyces, divide evenly to produce two new cells.
* During fission, the parent cell elongates, its nucleus divides & two offspring cells are produced.
~Fungi~
Cell type:
Cell membrane:
Cell wall:
Spores:
Metabolism:
~Fungi~
Cell type: Eukaryotic
Cell membrane: Sterols present
Cell wall: Glucans; mannans; chitin (no peptidoglycan)
Spores: Sexual & asexual reproductive spores
Metabolism: Limited to heterotrophic; aerobic, facutatively anaerobic.
~Bacteria~
Cell type:
Cell wall:
Spores:
Metabolism:
~Bacteria~
Cell type: PROKARYOTIC
Cell wall: Sterols absent, except in Mycoplasma (italics)
Spores: endospores (not for reprodcution); some asexual reproductive spores.
Metabolism: Heterotrophic, autotrophic, aerobic, facultatively anaerobic, anaerobic
Fungi cell type:
Eukaryotic
Fungi cell membrane:
Sterols present
Fungi Cell wall:
Glucans; mannan; chitin (no peptidoglycan)
Fungi spores:
Sexual & asexual reproductive spores
Fungi metabolism:
limited to heterotrophic; aerobic, facultatively anaerobic.
Bacteria cell type:
Prokaryotic
Bacteria cell membrane:
Sterols absent, except in Mycoplasma (italics)
Bacteria cell wall:
Peptidoglycan
Bacteria spores:
Endospores (not reproduction); some asexual reproductive spores.
Bacteria metabolism:
Heterotrophic, autotrophic; aerobic, facultatively anaerobic, anaerobic
_____ are capable of facultative anaerobic growth.
Yeasts
_____ can use oxygen or an organic compound as the final electron acceptor; this is a valuable attribute because it allows these fungi to survive in various environments.
Yeasts
What is the benefit for yeast using oxygen or an organic compound as the final electron acceptor?
It allows fungi to survive in various environments.
If given access to oxygen yeasts will
perform aerobic respiration to metabolize carbohydrates to carbon dioxide & water.
If denied oxygen yeasts will
ferment carbohydrates & produce ethanol & carbon dioxide.
* This fermentation is used in the brewing, wine-making & baking industries.
Saccharomyces species
produce ethanol in brewed beverages & carbon dioxide for leavening bread dough.
Dimorphic Fungi-
Some fungi, most notably the pathogenic species, exhibit DIMORPHISM- 2 forms of growth.
* Such fungi can grow either as a mold or as a yeast.
The moldlike forms produce-
vegetative & aerial hyphae
The yeastlike forms
reproduce by budding
dimorphism in pathogenic fungi is temperature-dependent: at
37°C, the fungus is yeastlike
dimorphism in pathogenic fungi is temperature-dependent: at
25°C, it is moldlike
However, the appearance of the dimorphic (nonpathogenic) fungus changes with
CO2 concentration.
Life cycle~
Filamentous fungi can reproduce-
asexually by fragmentation of their hyphae.
Both sexual & asexual reproduction in fungi occurs by the formation of
spores.
Usually fungi are identified by what?
Spore type
Are fungal spores different from bacterial endospores?
Yes, quite different.
Bacterial endospores allow a bacterial cell to
survive adverse environmental conditions.
A single vegetative bacterial cell forms
one endospore, which eventually germinates to produce a single vegetative bacterial cell.
* this process is not reproduction BECAUSE it does not increase the total number of bacterial cells.
After a mold forms a spore, the spore detaches from the parent & germinates into a new mold.
*Unlike the bacterial endospore, this is a true reproductive spore; a 2nd organism grows from the spore.
Survival of fungal spores:
Although fungal spores can survive for extended periods in dry or hot environments, most do not exhibit the extreme tolerance & longevity of bacterial endospores
Spores are formed from
aerial hyphae in a number of different ways, depending on the species.
*fungal spores can be either asexual or sexual
Asexual spores:
are formed by the hyphae of one organism.
* When these spores germinate, they become organisms that are genetically identical to the parent.
Sexual spores:
result from the fusion of nuclei from 2 opposite mating strains of the same species of fungus.
Fungi produce sexual spores LESS frequently than
asexual spores.
Organisms that grow from sexual spores will
have genetic characteristics of both parental strains.
Asexual Spores:
Asexual spores are produced by an individual fungus through MITOSIS & SUBSEQUENT CELL DIVISION.
*there is no fusion of the nuclei of cells.
What are the 2 types of asexual spores produced by fungi?
1. Conidiospore or conidium
2. Sporangiospore
Conidiospore or Conidium:
a unicellular or multicellular spore that is not enclosed in a sac.
How are Conidia are produced?
In a chain at the end of a conidiophore. Such spores are produced by Aspergillus (italics).
Conidia formed by the fragmentation of a septate hypha into single, slightly thickened cells are called ____________.
arthroconidia
Another type of conidium, ____________, consists of buds coming off the parent cell.
blastoconidia
Blastonconida are found in some yeasts, such as
Candida albicans & Cryptococcus (both in italics).
Chlamydoconidium
is a thick-walled spore formed by rounding & enlargement within a hyphal segment.
A fungus that produces chlamydoconidia is the yeast
C. albicans (italics)
Sporangiospore
formed within a sporangium, or sac, at the end of an aerial hypha called a sporangiophore.
The sporangium can contain
hundreds of sporangiospores.
*such spores are produced by Rhizopus (italics)
Sexual Spores: A fungal sexual spore results from sexual reproduction, which consists of 3 phases:
1. Plasmogamy
2. Karyogamy
3. Meiosis
Plasmogamy:
A haploid nucleus of a donor cell (+) penetrates the cytoplasm of a recipient cell (-).
Karyogamy:
The (+) & (-) nuclei fuse to form a diploid zygote nucleus.
Meiosis:
The diploid nucleus gives rise to haploid nuclei (sexual spores), some of which may be genetic recombinants.
The sexual spores produced by fungi characterize the ___.
phyla
In laboratory settings, most fungi exhibit only ____ spores.
asexual
Clinical identification is based on microscopic examination of _____ spores.
asexual
Nutritional Adaptations-
Fungi are generally adapted to environments that would be hostile to bacteria.
Fungi are __________, and, like bacteria, they absorb nutrients rather than ingesting them as animals do.
chemoheterotrophs
Fungi differ from bacteria in certain environmental requirements & in the following nutritional characteristics:
Fungi usually grow better in an environment with a pH of about 5, which is too acidic for the growth of most common bacteria.
Fungi differ from bacteria in certain environmental requirements & in the following nutritional characteristics:
Almost all molds are aerobic. Most yeasts are facultative anaerobes.
Fungi differ from bacteria in certain environmental requirements & in the following nutritional characteristics:
Most fungi are more resistant to osmotic pressure than bacteria; most can therefore grow in relatively high sugar or salt concentrations.
Fungi differ from bacteria in certain environmental requirements & in the following nutritional characteristics:
Fungi can grow on substances w/a very low moisture content, generally too low to support the growth of bacteria.