Bacteria, Protists, and Fungi Flashcards
“…evolution produces a tree, not a ladder — and we are just one of many twigs on the tree.”
Phylogenetic trees depicts the evolutionary relationships of about 3,000 species throughout the Tree of Life. Less than 1 percent of known species are depicted.
Domain
the highest level of hierarchy
Three domains:
Bacteria, Archaea, and Eukarya
Bacteria
no nucleus, single-celled
PROKARYOTES
Archaea
no nucleus, single-celled
PROKARYOTES
Eukarya
have a nucleus
cells can be either single-celled or multicelled
EUKARYOTES
The origin of prokaryotes
At least 3.6 billion years old
Fossil stromatolites (still can be found today); consist of layers of bacterial mats.
First prokaryotes likely appeared much earlier.
Early photosynthetic prokaryotes produced an oxygen atmosphere.
Most common form of movement in prokaryotes
Flagella
Prokaryotes Disease: cause about half of all human diseases
TB (Mycobacterium tuberculosis)*
Cholera (Vibrio cholerae) outbreaks in untreated water
Syphilis (Treponema pallidum)* why easily treated
Lyme disease (Borrelia burgdorferi)* most widespread pest-carried disease in U.S.
Anthrax (Bacillus anthracis)
Legionnaire’s disease (Legionella sp.)
Escherichia coli (part of our natural gut flora, but type O15:H7 is dangerous.)
Plague (Yersinia pestis)
Syphilis
Bacterial Disease Syphilis can be easily treated with antibiotics, usually by injections. Gonorrhea (Neisseria gonorrhoeae) Strep infection (Streptococcus sp.) Chlamydia trachomatis* most common STD Clostridium botulinum* BOTOX MRSA (now VRSA?)
(BUT Harmful prokaryotes are in the minority)
Prokaryotes: What we don’t think of
Collective mass is 10 times of eukaryotes
If reproduction unlimited colony could outweigh Earth in 3 days.
Differences between bacteria and eukaryotes allow antibiotics to
disrupt RNA and ribosomes (erythromycin and tetracycline)
disrupt bacterial cell walls
Prokaryotes: What we don’t think of
Collective mass is 10 times of eukaryotes
If reproduction was unlimited colony could outweigh Earth in 3 days.
Differences between bacteria and eukaryotes allow antibiotics to disrupt RNA and ribosomes (erythromycin and tetracycline) and to disrupt bacterial cell walls.
Bacteria
All share a common ancestor
Originated ~ 3.8 billion years ago
Single-celled prokaryotes
Asexual reproduction
Also exhibit horizontal gene transfer
Bacterial Classification
3 basic shapes:
Coccus (round)
Bacillus (rod)
Spirillum (spiral)
Gram Staining differentiates between 2 major groups based on cell wall structure:
Gram-Positive
Gram Negative
Humans and Bacteria
There are 10 times as many bacterial cells in your body than human cells!
There are more bacterial cells in your stomach than there are people on the planet
Benefits of Bacteria
“normal flora”
Probiotic therapy: swamp your body with benign/helpful bacteria to outnumber harmful bacteria fight bacteria with bacteria
Thermus aquaticus
One of the most important bacterial discoveries
Used in polymerase chain reaction (PCR)
Found in hot springs
Future Possibilities
Bacteria as data storage
http://news.discovery.com/tech/biotechnology/bacteria-work-as-hard-drives-110110.htm
Detecting Landmines
http://www.treehugger.com/clean-technology/scientists-create-bacteria-that-lights-up-around-landmines.html
Archaea
Similarities with bacteria:
appearance
prokaryotes
single-celled
Big differences with bacteria:
DNA
cell wall chemical composition
flagella
Archaea cont…
“Extremophiles”
- hydrothermal vents
- acidic water
- salty water
- places in which most proteins would denature
Found almost everywhere, including in your intestines:
break down bonds in beans, release methane
Bells and Whistles of Eukarya
Nucleus
Cytoskeleton:
Controls shape of cell and movement of internal elements
Mitochondria:
Allow oxidative metabolism
Chimeric genome:
Some genes from Bacteria, some from Archaea, and some unique to Eukarya.
(for some, chloroplasts)
In the course of evolution, genomes grow. HOW?
Eukaryotes typically have 5-20X number of genes of prokaryotes
New genes arise by duplication of existing genes– with subsequent divergence of function
the constraints on single cells
Cells must stay small because of
- water
- nutrients
- wastes
Tissues
Tissues are not just aggregations of cells – the cells in tissues are connected by intercellular junctions and function as a unit
Junctions hold cells together and also allow communication between cells (e.g., transfer of small molecules)
The evolution of multicellularity
Likely began with coloniality with subsequent cell specialization.
Coloniality has evolved independently in many prokaryote and protist lineages.
Multicellularity has evolved independently in several eukaryote groups.
What is significance of independent development?
Protists
Extremely diverse
Share one feature: eukaryotic
Defined by exclusion:
They just do not belong to any other kingdom.
Classification is being reconsidered; there may be as many as 20 kingdoms
Protist diversity
Range from single-celled protists to enormous multicellular organisms (algae)
“Protists” exhibit wide range of “body plans” and include the most complex living cells
Protist Classification
“Traditional” groupings: Animal-like protists – protozoans (chemoheterotrophs) Plant-like protists – algae (photoautotrophs) Fungus-like protists – molds Chemoheterotrophs (often saphrophytic-[feeds on dead or decaying matter])
chemoheterotrophs
An organism deriving energy by ingesting intermediates or building blocks that it is incapable of creating on its own.
Most chemoheterotrophs obtain energy by ingesting organic molecules like glucose.
Word origin: Gk: Chemo = chemical, hetero = (an)other, troph = nourishment Related forms: chemoheterotrophic (adjective)
Also called: chemotrophic heterotroph
Chemotrophs are organisms that obtain energy by the oxidation of electron donors in their environments. These molecules can be organic or inorganic. The chemotroph designation is in contrast to phototrophs, which utilize solar energy.
protozoans
Animal-like protists;
chemoheterotrophs
algae
Plant-like protists;
photoautotrophs
molds
Fungus-like protists;
Chemoheterotrophs (often saphrophytic)
Protist Classification
“Traditional” groupings:
Animal-like protists – protozoans
(chemoheterotrophs)
Plant-like protists – algae
(photoautotrophs)
Fungus-like protists – molds
Chemoheterotrophs (often saphrophytic-[feeds on dead or decaying matter])
chemoheterotrophs
An organism deriving energy by ingesting intermediates or building blocks that it is incapable of creating on its own.
Most chemoheterotrophs obtain energy by ingesting organic molecules like glucose.
Word origin: Greek: Chemo = chemical, hetero = (an)other, troph = nourishment Related forms: chemoheterotrophic (adjective)
Also called: chemotrophic heterotroph
Chemotrophs are organisms that obtain energy by the oxidation of electron donors in their environments. These molecules can be organic or inorganic. The chemotroph designation is in contrast to phototrophs, which utilize solar energy.
photoautotrophs
An organism obtaining energy from sunlight as its source of energy to convert inorganic materials into organic materials for use in cellular functions such as biosynthesis and respiration.
In order to capture light as source of energy, photoautotrophs carry out photosynthesis, converting energy from sunlight, carbon dioxide and water into organic materials. Photoautotrophs provide nutrition for many forms of life. They include the plants, algae and certain protists bacteria.
Word origin: Greek: photo = light, auto = self, troph = nourishment Related forms: photoautotrophic (adjective)
“Plant-Like” Protists
Algae: photosynthetic protist living in water
Range in size
Use different photosynthetic pigments: yellow, gold, brown, red and green
Seaweed
Plant-like protists
a macroscopic, multicellular, benthic marine algae
Used as a source of food for humans:
Sherberts, chocolate milk, cheeses, instant pudding, mayonnaise, ice cream, etc
Used in fertilizer, soil conditioner, animal feed, facial mask, massage gel, vitamins, seaweed baths, toothpaste, make-up, soaps, shampoo, shaving cream, shower gel…..
“Fungus-Like” Protists
Plasmodial Slime Molds
Cellular Slime Molds
Slime Mold
“Animal-Like” Protists
Most are unicellular
Giardia
Chagas disease
African sleeping sickness
Malaria
Fungi: Basics
Domain: Eukarya
Kingdom: Fungi
Similar to plants, but
- lack chloroplasts
- do not photosynthesize
- some are unicellular (ex: yeast)
- heterotrophic (mostly decomposers)
fungi are more closely related to
animals than plants
Relationship of Fungi to Animals
Molecular genetic studies suggest fungi share a common ancestor with animals
Features shared with animals:
Cells walls contain chitin (as in some animals), not cellulose (as in plants)
Carbohydrates stored as glycogen (as in animals) and not as starch (as in plants)
Currently, 5 phlya of fungi
Chytrids (water and soil)
Zygomycetes (rot produce, fast growing)
Glomeromycetes (90% of plants have these on roots)
Ascomycetes (morels, truffles, bread molds, yeast)
Basidiomycetes (toadstools)
Fungi feeding
Absorptive heterotrophs (like many prokaryotes)
“Digest then ingest” - digestive enzymes secreted into surroundings; fungus then absorbs the digested products
Most are decomposers: Some are parasitic, and some symbiotic
Fungi: Structure
The body of most fungi is a network of thin filaments which
- provides a large surface area for absorbing nutrients
- penetrates the fungus’s food source
- secrete enzymes that break down organic molecules
- absorb resulting nutrients
hyphae
tiny filaments of fungi that form a network underground and a “body” above
mycelium
the interwoven network of hyphae
underground (or in a substrate)
sporulation
the release of spores
hyphae
tiny filaments of fungi that form a network underground and a “body” above
mycelium
the interwoven network of hyphae underground (or in a substrate)
Fungi: Chytrids
primitive fungi that produce swimming spores
- flagellum
Chytridomycota: Killing The Frogs
Zygomycota
Ruining Your Food
Glomeromycota
The Feeling is Mutual
Mycorrhizal fungi form symbiotic relationships with plant roots.
- Helps plant better absorb nutrients
- Fungus gets carbohydrates from plant
- mutually beneficial relationship
- very common
Essential ECOLOGICALLY: Glomerocytes and mycorrhizae
Associated with > 90% of plants.
Improve water/mineral uptake by plant roots.
Plant roots provides carbohydrates to fungus.
ALL glomerocytes form arbuscular mycorrhizae.
Ascomycota
“Bringing Friends Together”
Important ECONOMICALLY
Saccharomyces cerevisiae = Ascomycete yeast:
- single-celled fungus
- mostly asexual
- inhabits liquid or moist environments
- responsible for bread and wine and beer
Important GASTRONOMICALLY Some of the most famous edible mushrooms are ascomycetes - Morels - Truffles - Other molds in cheeses
Ascomycota
“Bringing Friends Together”
Important ECONOMICALLY
Saccharomyces cerevisiae = Ascomycete yeast:
- single-celled fungus
- mostly asexual
- inhabits liquid or moist environments
- responsible for bread and wine and beer
Important GASTRONOMICALLY Some of the most famous edible mushrooms are ascomycetes - Morels - Truffles - Other molds in cheeses
Important MEDICALLY (good and bad)
- Penicillium mold (ascomycete) - the source for penicillin, the first antibiotic.
Alexander Flemming, Nobel Prize in 1945 for discovery of penicillen
- Claviceps purpurea, which infects rye plants, is responsible for ergot poisoning.
- Vaginal yeast infection (Candida albicans)
Basidiomycota
Tasty, Fun or Deadly?
toadstoals
Fungi: Lichens
Relationship between a fungus and photosynthesizer (green algae or cyanobacteria)
Can live in extreme conditions and is important in making soil, but is sensitive to pollution
Fungus provides protected environment and minerals for the autotrophs, while the autotrophs supply carbohydrates
Lichens often the first colonizers of bare rock and are likely one of the first land colonizers
Can resist harsh, exposed conditions
