microbiology 8 (other subcellular components) Flashcards
whereas _______ are found in both the gram negative and gram positive bacteria.
the fimbriae
the _______are bristle-like short fibres occurring on the bacterial surface
fimbriae
_______are long hair-like tubular microfibers found on the surface of bacteria
Pili
Pili generally longer
true/false
true
how are both pili and fimbriae involved in attachment of bacterial cell to host? list 2
- Bind to lectins on cell surfaces, e.g sugar binding proteins
- Gives tissue specificity
Bacteria within a human host are constantly losing and reforming fimbriae
(true/false)
true
pili and fimbriae aids in evasion of the immune system.
true/false
true
which type of bacteria can change the antigenic structure of their pili/fimbriae
N. gonorrhoea
_______ is Used by conjugative plasmids to transfer copies of itself to a new host
sex pili and conjugation
Sometimes other genetic material is mobilised during conjugation
true/false
true
After conjugation the previously _______has a copy of the ________and is able to pass it on to ________
- negative cell
- plasmid
- another cell
______ is an Efficient manner for transfer of antimicrobial resistance
sex pili and conjugation
state the four steps of sex pili and conjugation.
- donor cell attaches to a recipient cell with its pilus. the pilus draws the cells together.
- the cells contact one another
- one strand of plasmid DNA transfers to the recipient.
- the recipient synthesizes a complementary strand to become an F+ cell; the donor synthesizes a complementary strand restoring its complete plasmid.
The ______of E. coli can also mobilise the _______to be transferred through _______
F plasmid
chromosome
cell to cell contact
________ integrates into the chromosome and leads to transfer of large regions of the host genetic material and extensive genetic recombination.
episome
Hfr is an ______
episome
Cells already containing _______ are poor recipients for the same or similar plasmid
a plasmid
state the four steps of Hfr-specific recombination
- Hfr cells contain genes that allow them to transfer some or all of their chromosome to another cell.
- conjugation tube connects Hfr cell to normal cell. copy of Hfr chromosome begins to move recipient cell.
- homologous sections of chromosome synapse.
- cells separate. section of Hfr chromosome integrates into recipient chromosome by crossing over.
_______ consists of polysaccharide or sometimes protein. General term is glycocalyx
Capsules and slime layers
what is capsule
Thick viscous gel outside and attached to cell wall
what is slime
Capsule loosely attached to cell wall and easily washed off
Capsules and slime layers are both are hydrophilic.
true/false
true
what do Capsules and slime layers appear as in a gram stain?
Appear as halos around cells
what are the features of the Microcapsule of E. coli and Salmonella spp?
- Too thin to be seen on light microscope
- Detected by antisera
most capsules are ________
immunogenic and stimulate antibody response
why aren’t Group B meningococci immunogenic and stimulate antibody response.
its capsule contains N-acetylneuraminic acid which is found on host cells
why aren’t S. pyogenes capsule immunogenic and stimulate antibody response.
Hyaluronic acid of S. pyogenes capsule can lead to host cell damage because found on host cells.
list 5 advantages of capsules to bacteria.
- Protect cells from desiccation and toxic material
- Attachment to host cells
- Soluble material released into solution blocks opsonising antibodies
- Resist complement alternative pathway
- Resist phagocytosis by neutrophils
where do Prokaryotic protein synthesis take place?
Takes place on ribosomes, 70S (30S+50S) in the cytoplasm
30S contains ________(small subunit)
while 50S contains_______ (large subunit)
16S RNA
23S RNA
how many ribosomes in a prokaryote cell.
Up to 10,000 ribosomes
Bacterial mRNA is __________
polycistronic (multiple genes on one mRNA)
in bacteria mRNA can be translated________
by several ribosomes simultaneously
in prokaryotes Protein translation is done via ____ and _____
tRNA and mRNA
Location of protein encoding genes determined by ___________:
looking for Open Reading Frames (ORF)
what are two components of cytoplasm.
- Enzymes and ions and a variety of granules
- Accumulation of food reserves (polysaccharides, lipids or polyphosphates)
One of the most common inclusion bodies in cytoplasm consists of_______
poly-beta-hydroxybutyric acid
_______ is used as storage for carbon and energy storage polymers.
cytoplasm
plasmids are ______ and _______
circular and autonomously replicating
