Flashcards in Microbio 3-18 structure function Deck (98)
What are two important bacteriological procedures?
sterilization & aseptic technique
What's the difference between sterilization and aseptic technique?
Sterilization - preparation of media/instruments such that no living bacteria are present. Aseptic Technique: allows manipulation of sterilized material without bacteriological contamination
What is the first basis of classification for bacteria? What are two examples? How are they classified today?
shape. 1) cocci (round-shaped) and 2) bacilli (rod-shaped). They are now classified depending on the extent of DNA sequence homology
How do you identify a gram + from a gram - stain?
Gram + is violet; Gram - is red
What are the 4 most important bacterial characteristics?
1) morphology of colonies on appropriate agar medium. 2) microscopic morphology and staining of individual bacteria. 3) biochemical profiles (ability to ferment a particular sugar). 4) specific antigens detected by known anti-sera
What are Koch's postulates? (4)
1) the MO must be PRESENT in all organisms suffering from the disease, but not in healthy organisms. 2) the MO must be isolated from a diseased organism and grown in pure culture. 3) the cultured MO should cause disease when introduced into a healthy organism. 4) the MO must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.
Can Koch's postulates be applied to all MO? Why/Why not?
No, not all infectious bacterium will fulfill Koch's postulates (ie those that cannot grow on laboratory medium, but requir a host cell to grow)
What are Koch's molecular postulates?
1) the phenotype under investigation should be ASSOCIATED significantly more often with a pathogenic organism than with a nonpathogenic member or strain 2) Specific INACTIVATION of a gene (or genes) associated with the suspected virulence trait should lead to a measurable derease in virulation 3) RESTORATION of full pathogenicity should accompany replacement of the mutated gene with the wild-type organism
Name whether Fungi, Protozoa, and Bacteria have pathogens, are photosynthetic, or if they have a rigid cell wall.
Fungi has some pathogens, non-photosynthetic, and has a rigid cell wall. Protozoa have some pathogens, no rigid cell wall, non-photosynthetic. Bacteria have many pathogens, require organic compounds as energy source (but some of the are photosynthetic), and all (but one) have a rigid cell wall.
MOs are divided into two sub-groups on the basis of the structure of the individual cell. What are they?
Prokaryotes and Eukaryotes
What are examples of eukaryotes? (3) What are examples of prokaryotes? (1)
E: fungi, protozoa, algae. P: bacteria
How do eukaryotes and prokaryotes differ in terms of their chromosomes and their segregation?
E: linear chromosomes contained within nuclear membrane (segregation involves mitosis) P: one circular chromosome not bound by a nuclear membrane (segregation does not involve mitosis)
How do eukaryotes and prokaryotes differ in terms of their sexual reproduction?
E: sexual reproduction occurs by meiosis P: reproduction occurs by partial, unidirectional transfer of DNA
How do eukaryotes and prokaryotes differ in terms of their membrane bound structures?
E: contains mitochondria that carries out oxidative phosphorylation. P: no mitochondria, but oxidative phosphorylation occurs at the cell membrane
How do eukaryotes and prokaryotes differ in terms of their mobility?
E: motbility accomplished by cytoplasmic streaming (amoeboid movement) or by contraction of flagella (microtubule 9 doublet x 2 singlet arragement surrounded by cell membrane) P: flagella (flagellin subunits forming a central hollow tube) are present in some bacteria and it is not surrounded by cell membrane
How do eukaryotes and prokaryotes differ in terms of their cell wall?
E: animal cells do NOT have cell walls. Higher plants/algae have cell walls that are comprised of CELLULOSE (glucose polymer). Fungi have cell walls that are comprised of CHITIN (acetyl glucosamine polymer) and B-1,3-GLUCAN. P: cell walls are comprised of PEPTIDOGLYCAN, which consists of N-ACETYL glucosamine (NAG) lined to MURAMIC ACID (acetyl glucosamine linked to lactic acid), D-AMINO ACIDS. and other UNUSUAL A.A.
Penicillin affects with what component of the prokaryotic cell?
it inteferes with the formation of the peptidoglycan (ie it interferes with the cross-linking between polymer chains)
What ribosomes are present in eukaryotes vs prokaryotes?
E: 80S, P: 70S (think: P's are simpler and have a smaller ribosome)
Sterols are present in eukaryotic cells, but absent in prokaryotic cells. What is the one exception?
mycoplasma, which may contain sterols in their membrane.
In a clinical specmiens,how would you tell whether a cell is a bacteria or a cell from the host?
cells larger than 10µm are not bacteria
How do eukaryotes and prokaryotes differ in terms of their RNA/protein synthesis?
E: RNA is transcribed in the nucleus, spliced, and transported out to the ER, where it is transported into protein. P: nascent RNA is translated as it is transcribed and RNA splicing does NOT occur
Prokaryotes are subdivided into these two major groups:
bacteria (true bacteria) and archaea (which inhabit unusual environmental niches)
What are the general morphological types of bacteria?
1) cocci (spherical), 2) bacillus (rod shaped), 3) curved rod or spiral
How do most bacteria multiply?
What is binary fission?
form of asexual reproduction/cell division used by all prokaryotes, and some organelles within eukaryotic organisms (ie mitochondria). The single DNA molecule first replicates and each is then attached a different part of the cell membrane. A central tranvesere wall forms between the two daughter cells. When the cell begins to pull apart, the chromosomes are separated. Results in genetically identical cells
What are filaments and what type of bacterial cells are they most common in?
filaments are bacteria cell-aggregates that occur when the daughter cells do not separate after completion of the transverse wall
How are streptococci cells usually arranged?
chain of cocci
How are staphylococci cells usually arranged?
How are aerobic bacilli cells usually arranged?
chains of rods (think hot dog links)