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Terms in this set (60)
Organisms w/o a nucleus. Most are unicellular, although some aggregate into colonies. Usually very small, 0.5-5 μm (smaller than the 10-100 μm of many eukaryotic cells). Three common shapes. Most have a cell wall, which maintains shape, provies protection, and prevents cell from bursting in hypotonic environment.
Eubacteria, Archaea, Eukarya
The bacteria of kingdom eubacteria are heterotrophic, autotrophic, and chemotrophic. Heterotrohps absorb organic materials down in both living and dead organisms. Autotrophs can make their own food by photosynthesis. Chemotrophs get their food by breaking down inorganic matter.
Substance in most bacterial cell walls. Network of modified-sugar polymers cross-linked by short polypeptides.
Technique to classify bacteria into two groups based on cell wall composition. Developed by 19th century scientist Hans Christian Gram. Important diagnostic tool in determining treatment of bacterial infections.
Cell wall is more complex, with an outer membrane over the peptidoglycan layer. Also has less peptidoglycan overall. Crystal violet is rinsed off easily, and cell stains pink/red.
Outer membranes can be toxic. Gram (-) bacteria are also more resistant to antibiotics because membrane inbihits entry of drugs.
Simpler walls, large amount of peptidoglycan as an outer layer that traps crystal violet (and thus stains the bacteria purple).
Antibiotics work better on these because many of them inhibit peptidoglycan cross-linking.
Mycoplasma is a genus of bacteria that lack a cell wall. Without a cell wall, they are unaffected by many common antibiotics such as penicillin that target cell wall synthesis.
Safe antibiotics against gram-positive bacteria are widely available; gram-negative bacteria require more intense (and dangerous) drugs.
First antibiotic discovered; works against gram (+) bacteria by inhibiting peptidoglycan cross-linkages, thus weakening the bacterial cell wall.
Effective against gram (-) bacteria. Interferes with protein synthesis by binding to bacterial ribosome. Doesn't kill human ribosomes, because we have different kind of ribosomes.
Polysaccharide or protein layer covering many prokaryotes. Effects:
- enable prokaryotes to adhere to substrates or other individuals in a colony
- protect against dehydration
- shield pathogenic prokaryotes from host's immune system (i.e., ours!)
Gram-positive, anaerobic bacteria that is pathogenic and causes such things as pneumonia, meningitis, and acute sinusitis.
appendages that pull two cells together prior to DNA transfer - NOT sex. (longer, less numerous than fimbriae)
"attachment pili"; allow prokaryotes to attach to substrate or each other via hair-like protein appendages (shorter, more numerous than sex pili)
Structures that allow prokaryotic movement. Very different from eukaryotic flagella in molecular composition, mechanism of propulsion. May be scattered around surface of cell, or concentrated at one or both ends of cell.
In a heterogeneous environment, many bacteria exhibit this, which is the ability to move toward or away from certain stimuli.
Bacterial ribosomes differ in their protein and RNA content (from eukaryotic ribosomes), which allows us to use antibiotics to halt protein synthesis w/o harming ourselves.
Single chromosome (circular) of a bacterial cell is located here, in a non-membrane-bound region. There may also be separately replicating DNA called plasmids.
A resistant cell that develops when an essential nutrient is lacking. The original cell produces a copy of its chromosome and surrounds it w/a tough wall, producing the endospore. Water is removed from endospore, and metabolism stops. The original cell then disintegrates. The endospore can remain dormant (but viable) for centuries, able to rehydrate and resume metabolism when environment improves.
Gram-negative, rod-shaped bacterium that is commonly found in the gut of endotherms. Most strains are harmless, but some cause serious food poisoning.
Reproduction method of bacteria. 1 -> 2 -> 4 -> 8 etc.
horizontal gene exchange
Any process in which an organism incorporates genetic material from another organism without being the offspring of that organism.
When a prokaryotic cell takes up and incorporates foreign DNA from the surrounding environment.
Movement of genes between bacteria and bacteriophages (viruses that infect bacteria). Phages infect the donor cell, and one of the phages may take up a piece of the bacterial chromosome. Then that phage may infect another bacteria and insert not viral DNA, but the bacterial DNA from the donor cell to the recipient cell, causing recombination. This cell is called a "recombinant cell."
Process where genetic material transferred between bacterial cells via sex pili. DNA called F factor required for production of sex pili. F factor can exist as plasmid or w/in chromosome.
F⁺: male, has F factor, donor
F⁻: female, lacking F factor, recipient
F factor as a plasmid: Donor (male) transfers F⁺ characteristic to recipient (female) via sex pili, creating two F⁺ (male) cells
F factor as part of chromosome: Hfr cell (male) transfers part of chromosome to F⁻ (female) bacteria. Female uptakes part of Hfr's chromosome - but NOT F⁺ factor - during conjugation, resulting in a recombinant female cell.
Gram-negative bacteria, aka "blue-green algae" (NOT algae). Indicator of pollution: increases in numbers when pollutants added to water; nitrogen and phosphorus allow "algal bloom."
See cyanobacteria. NOT really algae.
Sudden increase in diversity of many animal phyla. Occurred 542 million years ago.
Formation of flint in Minnesota/Ontario where many unicellular (VERY old) fossils were found. I.e., bacteria.
Type of flint - rock that allows for fossilization of older organisms.
Rock that allows for formation of old fossils; chalky limestone.
More closely related to eukaryotes than other bacteria. Share some characteristics w/bacteria and others w/eukaryotes (see Table 27.2 in book.)
Archaea that live in very hot environments.
Live in swamps and marshes; anaerobes and are poisoned by O₂. Produce methane as a waste product.
Very small infectious particles. Are NOT living organisms; lack a key trait: independent reproduction (viruses can only reproduce inside other living cells).
DNA or RNA genes
Viral genomes may consist of:
- Double- or single-stranded DNA
- Double- or single-stranded RNA
The protein shell that encloses the viral genome. Can have various structures.
Some viruses have membraneous envelopes that help them infect hosts; surround the capsids. Dericed from the host cell's membrane. Contain combination of viral and host cell molecules.
Viruses have a limited number of host cells that it can infect. (Also called "host range.")
bacteriophage / phage
Viruses that attack bacteria. Best-understood of all viruses. Have two reproductive mechanisms: lytic cycle and lysogenic cycle.
Phage that reproduces only by the lytic cycle.
lytic pathway only
Phage reproductive cycle that results in the death of the host cell. Examples include T2, T4 (infect E. coli). Phage attaches to bacteria, inserts phage DNA, and degrades host DNA. Phage takes over biosynthetic machinery of host cell and synthesizes viral genomes and proteins. New phages assembled. Viral chromosome produces enzyme that lyses bacterial cell wall, and phages are released.
Destruction of cell wall (i.e., bacterial cell wall in lytic cycle by virus enzyme).
Replicates the phage genome w/o destroying the host. Phage injects DNA into host, phage DNA circularizes. (May go lytic or lysogenic at this point.) If going lysogenic: phage DNA integrages into bacterial chromosome, becoming a prophage. Bacterium reproduces, copying the prophage and transmitting it to daughter cells. This can repeat for many generations. At some point, the prophage will exit the bacterial chromosome, initiating the lytic cycle.
Phages that use both the lytic and lysogenic cycles. Examples include Lamba, λ.
lytic or lysogenic pathways
If there are few host cells, bacteria goes through the lysogenic pathway (doesn't want to destroy its source of reproduction). If there are many host cells, goes through the lytic pathway. Temperage phages have a way of sensing the concentration of host cells. Determination point is after phage DNA has circularized (which is after insertion of phage DNA).
prophage / provirus
Viral DNA which is integrated into the bacterial chromosome; happens during the lysogenic pathway. Humans have prophages in our DNA. Some have lost the ability to leave the cell (they are inactive).
A type of virus. Circular RNA molecules that infect plants and disrupt their growth. Very host-specific; only attack plants. May be escaped introns (non-coding sequences of mRNA).
See viroids. These "naked RNA" viruses do not have any genes.
avocado sun blotch, cucumber pale fruit
Diseases caused by viroids.
These VERY dangerous viruses propagate by converting normal proteins into misfolded prion versions. NOT host-specific. One prion can cause other normal proteins to misfold, which causes other normal proteins to misfold, which leads to aggregates of prions. These aggregates attack the CNS and brain, which leads to dead cells/holes in the brain. If you eat a prion, you get prion disease.
A protein (can be a prion) that is incorrectly folded; affects function of protein.
kuru, scrapie, BSE, CJD
Diseases caused by prions.
Another disease caused by a prion.
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