Week 2 Flashcards
Morphology
Cell size and shape.
Why is shape useful?
useful for distinguishing different microbial
cells
Micrometer
(μm or micron) is one-millionth of a meter in length.
What sizes are prokaryotic ranging between
Ranging between 0.5 and 10 in μm length, but prokaryotic cells can vary widely in size.
Smallest and largest prokaryotic
The smallest prokaryotic cells are about 0.2 μm in diameter and the largest can be more than 600 μm long.
Size range of eukaryotic cells
Between 5 and 100 μm in length
Smallest and largest eukaryotic size
The smallest eukaryotic microorganism known is about 0.8 μmin diameter
* The largest eukaryotic cells can be many centimeters in length.
What is cell size influenced by
cell structure
how do eukaryotic cells transport things
actively transport mlcls and macromlcls within the cytoplasm
how do prokaryotic cells transport things
Rely on diffusion for transport through the cytoplasm and this
limits their size.
when does the rate of diffusion increase
as the square of the distance
traveled
Epulopiscium fishelsoni
found in the gut of the surgeonfish, can be more than 75μm wide and 600μm long.
How many genomes does Epulopiscium fishelsoni have
has more than 10,000 copies of its genome distributed throughout its cytoplasm, thereby preventing diffusional limitation between the genome and any region of the cytoplasm.
Thiomargarita
The sulfur-oxidizing chemolithotroph
* about 750 μm in diameter
What does the S/V ratio control
- How fast it grows (its growth rate)
- Shape
what does cellular growth rate depend on
on the rate at which cells
exchange nutrients and waste products with their environment.
Coccus
A cell that is spherical or ovoid in morphology (plural, cocci).
Rod or a bacillus
A cylindrically shaped cell (plural, bacilli)
Spirillum
A spiral-shaped cell (plural, spirilla)
Vibrio
A cell that is slightly curved and comma-shaped.
Spirochete
A special kind of organism that has a spiral shape but which differs from spirilla because the cells of spirochetes are flexible, whereas cells of spirilla are rigid.
Appendages
such as stalks and hyphae, are used by some cells for attachment or to increase surface area.
Diplococci
cocci occur in pairs
Streptococci
form long chains
Tetrads or sarcinae
occur in three-dimensional cubes,
Staphylococci
occur in grapelike clusters
Filamentous bacteria
long, thin, rod-shaped bacteria that divide terminally and then form
long filaments composed of many cells attached end to end.
All known cellular organisms belong to these 3 domains
Bacteria
Archaea
Eukarya
What kind of structure does bacteria have
prokaryotic cell structure
Undifferentiated single cells with a length that ranges from 0.5 to 10μm.
* Diverse in appearance, size, and function.
* Most bacteria are unicellular
* Some bacteria can differentiate to form multiple cell types and others
are even multicellular (for example, Magnetoglobus).
More than 90% of cultivated bacteria belong to one of only four phyla:
- Actinobacteria
- Firmicutes
- Proteobacteria
- Bacteroidetes.
The domain Archaea consists of five described phyla:
Euryarchaeota
* Crenarchaeota
* Thaumarchaeota
* Nanoarchaeota
* Korarchaeota
Viruses
the most abundant microbes on
Earth: the population of viruses estimated to
outnumber bacterial and archaeal cells by a
factor of 10.
Virology
the study of viruses
why are viruses not found on the tree of life?
can multiply only inside a living cell, called the host cell.
Viruses are obligate intracellular parasites:
- host cell for energy
- metabolic intermediates
- protein synthesis
Virion
structurally intricate
extracellular form
Infection
Viruses cannot reproduce unless the
virion itself, or in some cases its genome only,
has gained entry into a suitable growing host
cell
Virions purpose
- protects the viral genome when the virus is outside
the host cell - proteins on the virion surface are important in
attaching it to its host cell.
Lytic pathway
The virus may replicate
and destroy the host in
a virulent infection via
a lytic pathway
Lysogenic Pathway
the host cell is not
destroyed and the viral
genome becomes part
of the host genome.
