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