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Terms in this set (19)
What are the major shapes of bacteria?
Bacilli, cocci, and spirilla.
There are some others like coccobacilli, square, and filamentous bacteria.
What are the motion and energy sources of bacterial flagellum?
The energy is provided by ions. Mostly by Protons, but some marine organisms use Sodium ions.
The flagella are NOT driven by ATP
How can motility be demonstrated on a soft-agar?
Streak a line of bacteria and test whether the colony swims outward. A dye can help identify the boundary.
What are the types of flagellar arrangement & what organism is an example?
-Monotrichous (Pseudomonas aruginosa)
-Amphitricous (Campylobacter jejuni)
-Lophotrichous (Helicobacter pylori)
-Bilophotrichous (rare...only in magnetic bacterium)
-Peritrichous (E. coli)
What end do the flagellum grow from, the base or the tip?
The tip. Monomer filament proteins migrate down the porous center to the tip.
What is bacterial chemotaxis?
Motile bacteria swim towards nutrients and away from danger.
What is the common function of pili/fimbriae?
adhering/sticking/binding to something.
What are the special functions of F or sex-pili?
They are longer and thicker pili that transfer DNA to other cells (conjugation). It is longer and thicker than other types and is also a receptor for bacteriophages (viruses that infect bacteria).
What is the function of a capsule?
Capsules are made of glycocalyx. They are uniform and condensed around the bacterial cell. They offer bacterium protection by:
-resisting changes in osmolarity
-sticking to smooth surfaces
-protecting against phagocytosis
What is the difference between S- and R.type colonies?
S-type colonies are bacterial colonies that have capsules. They appear to be smooth.
Those without capsules are called R-type colonies.
What does a cell wall do? What are advantages and disadvantages to having one? What are bacteria called when they don't have a cell wall? What are two pathogenic species that don't have a cell wall and what diseases do they cause?
A cell wall:
-gives the bacterium its shape, rigidity, and resistance to osmotic pressure differences. pretty much builds a skeleton.
-acts as a sifter for molecules being brought into the cell
-provides supporting matrix for the capsule, pili, frimbriae, and flagella
The disadvantages to not having a cell wall are that the cells are really sensitive to osmotic pressure cuz the cell doesn't really have a "skeleton".
The advantage is that antibiotics that disrupt the cell wall, like penecillin, don't work on these cells.
Mollicutes is the term for bacteria lacking a cell wall.
Mycoplasma pneumoniae => pneumonia
M. genitalium => urethritis
What are the two major classes of cell wall containing microbes?
Gram + and Gram -
What is the Gram stain protocol?
Crystal violet (blue dye) is fixed to the bacteria with iodine treatment. Everything is decolorized with alcohol/acetone mixture, then safrinin (red dye) is added.
Heat fix => Crystal violet => Iodine => De-colorize => Safranin
Differences between Gram + and - cells?
Gram-positive have a thick outer cell wall, but no lipids.
Gram-negative have a thin wall and an outer membrane (with lipids)
What are the only bacterial pathogens without a cell wall?
Mycoplasma & Ureaplasma
What are two other names for the peptidoglycan layer?
Murein and Mucopeptide.
Most gram-positive cells have... and most gram-negative cells have...
Gram-negative: diaminopimelic acid (resembles lysine)
Which gram-positive bacterium is unusual in that its cross-linkage is the pentapeptide of glycine?
What is unusual about the amino acids in the tetrapeptide crosslink?
They have D-amino acids
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